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Shelf life of HCl/H2O2

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  • Matthew Mucker
    I etched my first board a few weeks back with HCl/H2O2 and was very happy with the results. I saved the etchant, since I d only etched one small board with it,
    Message 1 of 22 , Jan 4, 2009
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      I etched my first board a few weeks back with HCl/H2O2 and was very happy
      with the results.

      I saved the etchant, since I'd only etched one small board with it, and
      today tried to etch a second board. I saw no evidence of a chemical
      reaction at all.

      Now, I know that H2O2 will spontaneously decompose, but it seems that the
      etchant should last longer than a couple of weeks. Has anyone else had
      issues with storing etchant and using it at a later date? Is there anything
      I can do to increase the shelf life of my etchant?
    • leon Heller
      ... From: Matthew Mucker To: Sent: Sunday, January 04, 2009 11:15 PM Subject: [Homebrew_PCBs] Shelf life
      Message 2 of 22 , Jan 4, 2009
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        ----- Original Message -----
        From: "Matthew Mucker" <matthew@...>
        To: <homebrew_PCBs@yahoogroups.com>
        Sent: Sunday, January 04, 2009 11:15 PM
        Subject: [Homebrew_PCBs] Shelf life of HCl/H2O2


        >I etched my first board a few weeks back with HCl/H2O2 and was very happy
        > with the results.
        >
        > I saved the etchant, since I'd only etched one small board with it, and
        > today tried to etch a second board. I saw no evidence of a chemical
        > reaction at all.
        >
        > Now, I know that H2O2 will spontaneously decompose, but it seems that the
        > etchant should last longer than a couple of weeks. Has anyone else had
        > issues with storing etchant and using it at a later date? Is there
        > anything
        > I can do to increase the shelf life of my etchant?

        You need to make up fresh etchant each time, it doesn't keep.

        Leon
      • Wayne Topa
        ... Leon I found a bunch of Curric Chloride (HCL+H2O2) links on Answers.com that say it does keep. I even went back in my archived mail and found a message
        Message 3 of 22 , Jan 4, 2009
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          leon Heller wrote:
          > ----- Original Message -----
          > From: "Matthew Mucker" <matthew@...>
          > To: <homebrew_PCBs@yahoogroups.com>
          > Sent: Sunday, January 04, 2009 11:15 PM
          > Subject: [Homebrew_PCBs] Shelf life of HCl/H2O2
          >
          >
          >
          >> I etched my first board a few weeks back with HCl/H2O2 and was very happy
          >> with the results.
          >>
          >> I saved the etchant, since I'd only etched one small board with it, and
          >> today tried to etch a second board. I saw no evidence of a chemical
          >> reaction at all.
          >>
          >> Now, I know that H2O2 will spontaneously decompose, but it seems that the
          >> etchant should last longer than a couple of weeks. Has anyone else had
          >> issues with storing etchant and using it at a later date? Is there
          >> anything
          >> I can do to increase the shelf life of my etchant?
          >>
          >
          > You need to make up fresh etchant each time, it doesn't keep.
          >
          > Leon
          >

          Leon

          I found a bunch of Curric Chloride (HCL+H2O2) links on Answers.com
          that say it does keep.
          I even went back in my archived mail and found a message from you, on
          Feb 22 2006, where you
          said you stored yours in plastic Milk bottles.

          I hope you just forgot because I just got together come HCL and 30%
          H2O2 to ecth a bunch of small
          boards. I was sure I had read some time ago that is did store for a
          long time with rejuvination.


          Am I mis-remembering, which I seem to be doing a lot lately, or has
          something changed.

          Wayne
        • Gaurav Verma
          Hi It is my understanding that H2O2 will decompose readely into H2O and O2 hence you will have to add fresh H2O2 to existing solution until the etchent becomes
          Message 4 of 22 , Jan 4, 2009
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            Hi
            It is my understanding that H2O2 will decompose readely into H2O and O2
            hence you will have to add fresh H2O2 to existing solution until the etchent
            becomes too dilute.
            Thanks
            Regards
            Gaurav

            On Mon, Jan 5, 2009 at 8:36 AM, Wayne Topa <linuxone@...> wrote:

            > leon Heller wrote:
            > > ----- Original Message -----
            > > From: "Matthew Mucker" <matthew@... <matthew%40mucker.net>>
            > > To: <homebrew_PCBs@yahoogroups.com <homebrew_PCBs%40yahoogroups.com>>
            > > Sent: Sunday, January 04, 2009 11:15 PM
            > > Subject: [Homebrew_PCBs] Shelf life of HCl/H2O2
            > >
            > >
            > >
            > >> I etched my first board a few weeks back with HCl/H2O2 and was very
            > happy
            > >> with the results.
            > >>
            > >> I saved the etchant, since I'd only etched one small board with it, and
            > >> today tried to etch a second board. I saw no evidence of a chemical
            > >> reaction at all.
            > >>
            > >> Now, I know that H2O2 will spontaneously decompose, but it seems that
            > the
            > >> etchant should last longer than a couple of weeks. Has anyone else had
            > >> issues with storing etchant and using it at a later date? Is there
            > >> anything
            > >> I can do to increase the shelf life of my etchant?
            > >>
            > >
            > > You need to make up fresh etchant each time, it doesn't keep.
            > >
            > > Leon
            > >
            >
            > Leon
            >
            > I found a bunch of Curric Chloride (HCL+H2O2) links on Answers.com
            > that say it does keep.
            > I even went back in my archived mail and found a message from you, on
            > Feb 22 2006, where you
            > said you stored yours in plastic Milk bottles.
            >
            > I hope you just forgot because I just got together come HCL and 30%
            > H2O2 to ecth a bunch of small
            > boards. I was sure I had read some time ago that is did store for a
            > long time with rejuvination.
            >
            > Am I mis-remembering, which I seem to be doing a lot lately, or has
            > something changed.
            >
            > Wayne
            >
            >
            >



            --
            Gaurav Verma
            Email - Gaurav.Verma.MCA@...
            Phone - 9910732960


            [Non-text portions of this message have been removed]
          • Stefan Trethan
            Now there s your problem. You don t have CuCl, you have HCl and H2O2. The one will keep, the other won t. You can make CuCl from HCL and H2O2 simply by etching
            Message 5 of 22 , Jan 5, 2009
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              Now there's your problem. You don't have CuCl, you have HCl and H2O2.
              The one will keep, the other won't.

              You can make CuCl from HCL and H2O2 simply by etching copper, but
              until you get there you have to add H2O2 each time you want to etch.

              ST

              On Mon, Jan 5, 2009 at 4:06 AM, Wayne Topa <linuxone@...> wrote:

              >
              > I found a bunch of Curric Chloride (HCL+H2O2) links on Answers.com
              > that say it does keep.
            • leon Heller
              ... From: Wayne Topa To: Sent: Monday, January 05, 2009 3:06 AM Subject: Re: [Homebrew_PCBs] Shelf
              Message 6 of 22 , Jan 5, 2009
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                ----- Original Message -----
                From: "Wayne Topa" <linuxone@...>
                To: <Homebrew_PCBs@yahoogroups.com>
                Sent: Monday, January 05, 2009 3:06 AM
                Subject: Re: [Homebrew_PCBs] Shelf life of HCl/H2O2


                > leon Heller wrote:
                >> ----- Original Message -----
                >> From: "Matthew Mucker" <matthew@...>
                >> To: <homebrew_PCBs@yahoogroups.com>
                >> Sent: Sunday, January 04, 2009 11:15 PM
                >> Subject: [Homebrew_PCBs] Shelf life of HCl/H2O2
                >>
                >>
                >>
                >>> I etched my first board a few weeks back with HCl/H2O2 and was very
                >>> happy
                >>> with the results.
                >>>
                >>> I saved the etchant, since I'd only etched one small board with it, and
                >>> today tried to etch a second board. I saw no evidence of a chemical
                >>> reaction at all.
                >>>
                >>> Now, I know that H2O2 will spontaneously decompose, but it seems that
                >>> the
                >>> etchant should last longer than a couple of weeks. Has anyone else had
                >>> issues with storing etchant and using it at a later date? Is there
                >>> anything
                >>> I can do to increase the shelf life of my etchant?
                >>>
                >>
                >> You need to make up fresh etchant each time, it doesn't keep.
                >>
                >> Leon
                >>
                >
                > Leon
                >
                > I found a bunch of Curric Chloride (HCL+H2O2) links on Answers.com
                > that say it does keep.
                > I even went back in my archived mail and found a message from you, on
                > Feb 22 2006, where you
                > said you stored yours in plastic Milk bottles.
                >
                > I hope you just forgot because I just got together come HCL and 30%
                > H2O2 to ecth a bunch of small
                > boards. I was sure I had read some time ago that is did store for a
                > long time with rejuvination.
                >
                >
                > Am I mis-remembering, which I seem to be doing a lot lately, or has
                > something changed.

                I was referring to the cupric chloride. The HCl-H2O2 simply doesn't keep.

                Leon
              • Wayne Topa
                ... Ah Ha, the rejuvination process, adding H2O2 before each etching session, until it becomes CuCl. Is that the stage where the solution changes color?
                Message 7 of 22 , Jan 5, 2009
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                  Stefan Trethan wrote:
                  > Now there's your problem. You don't have CuCl, you have HCl and H2O2.
                  > The one will keep, the other won't.
                  >
                  > You can make CuCl from HCL and H2O2 simply by etching copper, but
                  > until you get there you have to add H2O2 each time you want to etch.
                  >
                  >
                  Ah Ha, the rejuvination process, adding H2O2 before each etching
                  session, until it becomes
                  CuCl. Is that the stage where the solution changes color?

                  Thanks guys for refreshing my ageing memory.

                  Wayne
                • Stefan Trethan
                  The solution does get darker as more copper is dissolved, but slightly green doesn t mean there is anywhere near enough copper to etch a board. If you want to
                  Message 8 of 22 , Jan 5, 2009
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                    The solution does get darker as more copper is dissolved, but slightly
                    green doesn't mean there is anywhere near enough copper to etch a
                    board.

                    If you want to measure this, you can get a hydrometer. The ones sold
                    for car battery acid checks will usually do. A refractometer should
                    work as well.

                    Or you can just keep on etching and not worry about it, one day it
                    will be strong enough to make a board without adding any H2O2.

                    If this feature is very important to you just throw some scrap copper
                    in and etch it away, that'll rapidly increase the density.

                    ST

                    On Mon, Jan 5, 2009 at 5:25 PM, Wayne Topa <linuxone@...> wrote:

                    > Ah Ha, the rejuvination process, adding H2O2 before each etching
                    > session, until it becomes
                    > CuCl. Is that the stage where the solution changes color?
                    >
                    > Thanks guys for refreshing my ageing memory.
                    >
                    > Wayne
                    >
                    >
                  • DJ Delorie
                    ... This is what I ended up doing - I wasn t using the HCl/H2O2 solution often enough and had to keep evaporating off water to fit in more H2O2, so one day I
                    Message 9 of 22 , Jan 5, 2009
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                      "Stefan Trethan" <stefan_trethan@...> writes:
                      > If this feature is very important to you just throw some scrap copper
                      > in and etch it away, that'll rapidly increase the density.

                      This is what I ended up doing - I wasn't using the HCl/H2O2 solution
                      often enough and had to keep evaporating off water to fit in more
                      H2O2, so one day I just dumped about half a pound of copper into the
                      bucket and let it dissolve over a couple of days. *Then* I dumped in
                      some H2O2 to "charge" it (it turned from brown to green) and it's been
                      stable since then.

                      At this point, my solution is so dark green that you can't see the pcb
                      when you're etching it. Etching takes about 5-6 minutes, plenty fast
                      enough for me.

                      I calculated the ratio at about 1 lb copper to 3 l solution.
                    • Wayne Topa
                      ... Thanks Stefan and DJ. That is what I remember (now), that I read a few years ago. I believe that it was you fellows that got me interested in the first
                      Message 10 of 22 , Jan 5, 2009
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                        DJ Delorie wrote:
                        > "Stefan Trethan" <stefan_trethan@...> writes:
                        >
                        >> If this feature is very important to you just throw some scrap copper
                        >> in and etch it away, that'll rapidly increase the density.
                        >>
                        >
                        > This is what I ended up doing - I wasn't using the HCl/H2O2 solution
                        > often enough and had to keep evaporating off water to fit in more
                        > H2O2, so one day I just dumped about half a pound of copper into the
                        > bucket and let it dissolve over a couple of days. *Then* I dumped in
                        > some H2O2 to "charge" it (it turned from brown to green) and it's been
                        > stable since then.
                        >
                        > At this point, my solution is so dark green that you can't see the pcb
                        > when you're etching it. Etching takes about 5-6 minutes, plenty fast
                        > enough for me.
                        >
                        > I calculated the ratio at about 1 lb copper to 3 l solution.
                        >
                        >

                        Thanks Stefan and DJ. That is what I remember (now), that I read a few
                        years ago. I
                        believe that it was you fellows that got me interested in the first
                        place to try this.


                        Stefan, was it you who kept your CuCl in a double capped bottle with
                        small holes in each
                        "plastic?" cap to slow down the evaporation of the H2O2? And do you air
                        bubble the
                        solution?

                        DJ, do you keep yours CuCl in a rubbermaid kitchen container, with a
                        lid on it? If so, do
                        you air bubble the solution?

                        Thanks for your replys.

                        Wayne
                      • DJ Delorie
                        ... I keep it in a rubbermaid container, yes, with the lid on it when not in use. There s a hole in it where the air tube goes through, so it s not 100%
                        Message 11 of 22 , Jan 5, 2009
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                          Wayne Topa <linuxone@...> writes:
                          > DJ, do you keep yours CuCl in a rubbermaid kitchen container, with a
                          > lid on it? If so, do you air bubble the solution?

                          I keep it in a rubbermaid container, yes, with the lid on it when not
                          in use. There's a hole in it where the air tube goes through, so it's
                          not 100% sealed (just 99.9% :).

                          I use an air stone bubbler when I'm etching, as well as an aquarium
                          heater. I turn both on about half an hour before etching (i.e. early
                          in the whole print/develop/etch process) but remove the lid at that
                          time. I don't store the heater in the etchant, but I do leave the air
                          stone in.

                          I do have a vent hood over the whole works, too.
                        • Stefan Trethan
                          At first i was going to say you must be mistaken, but then i remembered a few years ago i actually kept this etchant in the described bottle. You have a better
                          Message 12 of 22 , Jan 5, 2009
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                            At first i was going to say you must be mistaken, but then i
                            remembered a few years ago i actually kept this etchant in the
                            described bottle. You have a better memory than myself it seems.

                            Now i just keep it in the etching tank, which is by now second
                            generation already, made of 4mm glass with a phenolic board lid. The
                            lid sits on a rubber surface, to form a bit of a seal (but it's not
                            really airtight). To keep dust out (and maybe the fumes at bay a
                            little) i use a large plastic container over the whole setup, as a
                            lid. A similar container is underneath as a emergency catch basin so
                            this forms a neat closed box.

                            ST

                            On Mon, Jan 5, 2009 at 6:57 PM, Wayne Topa <linuxone@...> wrote:
                            > Stefan, was it you who kept your CuCl in a double capped bottle with
                            > small holes in each
                            > "plastic?" cap to slow down the evaporation of the H2O2? And do you air
                            > bubble the
                            > solution?
                          • DJ Delorie
                            ... I should point out that I, also, keep my etchant tank in a big catch basin. I also keep the sink water running whenever I m messing with the chemicals, in
                            Message 13 of 22 , Jan 5, 2009
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                              "Stefan Trethan" <stefan_trethan@...> writes:
                              > A similar container is underneath as a emergency catch basin so
                              > this forms a neat closed box.

                              I should point out that I, also, keep my etchant tank in a big catch
                              basin. I also keep the sink water running whenever I'm messing with
                              the chemicals, in case I need a quick rinse.
                            • Wayne Topa
                              ... Actually I don t. In researching Leon s reply, which I mis-read, I went back to try to refresh my memory before I mixes the chemicals. I read a lot of
                              Message 14 of 22 , Jan 5, 2009
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                                Stefan Trethan wrote:
                                > At first i was going to say you must be mistaken, but then i
                                > remembered a few years ago i actually kept this etchant in the
                                > described bottle. You have a better memory than myself it seems.
                                >
                                Actually I don't. In researching Leon's reply, which I mis-read, I went
                                back to try
                                to refresh my memory before I mixes the chemicals. I read a lot of
                                2006 posts and
                                thought it was you the used the double-cap bottle for storage.
                                > Now i just keep it in the etching tank, which is by now second
                                > generation already, made of 4mm glass with a phenolic board lid. The
                                > lid sits on a rubber surface, to form a bit of a seal (but it's not
                                > really airtight). To keep dust out (and maybe the fumes at bay a
                                > little) i use a large plastic container over the whole setup, as a
                                > lid. A similar container is underneath as a emergency catch basin so
                                > this forms a neat closed box.
                                >
                                Thanks to you an DJ, I am now, back in the loop so to speak. I went
                                back to my PCB
                                box and found the container that DJ mentioned in 2006. I had started
                                accumlating the
                                necessary items back then. It seems I have everything but the air pump
                                & stone so
                                I'm about set to finish projects I started way back then.

                                Many Thanks Stefan for all your help not only on this subject but from
                                all of your very
                                informative posts to this list over the years.

                                Happy New Year to you and yours,

                                Tschuss
                                Wayne
                              • Wayne Topa
                                ... Thanks DJ. As I mentioned to Stefan, it was your post in 2006 that I followed when I was putting together my PCB junk box. I see I have all but the air
                                Message 15 of 22 , Jan 5, 2009
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                                  DJ Delorie wrote:
                                  > Wayne Topa <linuxone@...> writes:
                                  >
                                  >> DJ, do you keep yours CuCl in a rubbermaid kitchen container, with a
                                  >> lid on it? If so, do you air bubble the solution?
                                  >>
                                  >
                                  > I keep it in a rubbermaid container, yes, with the lid on it when not
                                  > in use. There's a hole in it where the air tube goes through, so it's
                                  > not 100% sealed (just 99.9% :).
                                  >
                                  > I use an air stone bubbler when I'm etching, as well as an aquarium
                                  > heater. I turn both on about half an hour before etching (i.e. early
                                  > in the whole print/develop/etch process) but remove the lid at that
                                  > time. I don't store the heater in the etchant, but I do leave the air
                                  > stone in.
                                  >
                                  > I do have a vent hood over the whole works, too.
                                  >
                                  Thanks DJ. As I mentioned to Stefan, it was your post in 2006 that I
                                  followed when I was
                                  putting together my PCB junk box. I see I have all but the air pump so
                                  I'm good to go,

                                  Thanks again for the help, this time, and for the years of relaxation
                                  that the Ace of Penguins
                                  has given me and many others. You are a multi-tasker of the best kind.

                                  Happy New Year to you and Yours,

                                  Best regards,
                                  Wayne
                                • Markus Zingg
                                  I would like to switch to cucl for a while cause having a solution that lasts virtually for ever seems to be very beneficial. Besides, I m just before building
                                  Message 16 of 22 , Jan 6, 2009
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                                    I would like to switch to cucl for a while cause having a solution that
                                    lasts virtually for ever seems to be very beneficial. Besides, I'm just
                                    before building a new etching tank and thought that this would be a good
                                    moment for a switch of the etchant too. Since english is not my native
                                    language, I always felt a bit unsure if I understood things correctly if
                                    you guys were talking about cucl in the past, and there were always some
                                    open ends. In particular the following things are not yet clear to me:

                                    So, one would i.e. need to build 3l HCL/H2O2 and put in half a pound of
                                    copper into it? Correct?
                                    How many HCL and H2O2 to get to a 3l solution to start with? I mean
                                    what's the ratio of HCL to H2O2?
                                    Any restrictions regarding the kind of copper? I do have copper left
                                    over that I use for the anodes in my through plating station. Would that do?

                                    Then, Stefan wrote " If you want to measure this, you can get a
                                    hydrometer. The ones sold for car battery acid checks will usually do. A
                                    refractometer should work as well."

                                    A hydrometer - when useing google - seems to be a device to measure
                                    humidity? Correct? What is a "refractometer", which of the two would be
                                    easier to get and where, and how would one measure what? Regarding the
                                    "air stone bubbler", I think I remember that one uses this to regenerate
                                    the solution. If so, does one have to do this every once in a while, or
                                    only during etching, or just before?

                                    I'm sorry if these are dumb questions, but since working with chemistry
                                    might be dangerous I want to be very sure I understand things correcly
                                    bevore I start to experiment.

                                    TIA

                                    Markus

                                    DJ Delorie schrieb:
                                    >
                                    >
                                    > "Stefan Trethan" <stefan_trethan@...
                                    > <mailto:stefan_trethan%40gmx.at>> writes:
                                    > > If this feature is very important to you just throw some scrap copper
                                    > > in and etch it away, that'll rapidly increase the density.
                                    >
                                    > This is what I ended up doing - I wasn't using the HCl/H2O2 solution
                                    > often enough and had to keep evaporating off water to fit in more
                                    > H2O2, so one day I just dumped about half a pound of copper into the
                                    > bucket and let it dissolve over a couple of days. *Then* I dumped in
                                    > some H2O2 to "charge" it (it turned from brown to green) and it's been
                                    > stable since then.
                                    >
                                    > At this point, my solution is so dark green that you can't see the pcb
                                    > when you're etching it. Etching takes about 5-6 minutes, plenty fast
                                    > enough for me.
                                    >
                                    > I calculated the ratio at about 1 lb copper to 3 l solution.
                                    >
                                    >
                                  • Zoran A. Scepanovic
                                    Hello Markus, ... Device for measuring humidity is named HyGrometer: http://en.wikipedia.org/wiki/Hygrometer ... There are no dumb questions, only dumb answers
                                    Message 17 of 22 , Jan 6, 2009
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                                      Hello Markus,

                                      Tuesday, January 6, 2009, 10:02:35 AM, you wrote:

                                      > Then, Stefan wrote " If you want to measure this, you can get a
                                      > hydrometer. The ones sold for car battery acid checks will usually do. A
                                      > refractometer should work as well."

                                      > A hydrometer - when useing google - seems to be a device to measure
                                      > humidity? Correct? What is a "refractometer", which of the two would be

                                      Device for measuring humidity is named HyGrometer:
                                      http://en.wikipedia.org/wiki/Hygrometer

                                      > I'm sorry if these are dumb questions, but since working with chemistry

                                      There are no dumb questions, only dumb answers :)

                                      For Hydrometer: http://en.wikipedia.org/wiki/Hydrometer

                                      For Refractometer: http://en.wikipedia.org/wiki/Traditional_handheld_refractometer

                                      --
                                      Best regards,
                                      Zoran A. Scepanovic
                                      zastos@...

                                      *********
                                      COINCIDENCE happens.
                                      *********

                                      Please be advised what was said may be absolutely wrong,
                                      and hereby this disclaimer follows.
                                      I reserve the right to be wrong and admit it in front of the entire world.



                                      Local time: 10:40


                                      [Non-text portions of this message have been removed]
                                    • Stefan Trethan
                                      I can t actually give you the requested exact ratios since i built my etchant bit by bit and do not know them. However, i think you will have to do the same,
                                      Message 18 of 22 , Jan 6, 2009
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                                        I can't actually give you the requested exact ratios since i built my
                                        etchant bit by bit and do not know them.
                                        However, i think you will have to do the same, since at least the H2O2
                                        must be added gradually. At first there would not be enough Cu2Cl2 to
                                        oxidise, so much of the H2O2 would dissipate.

                                        The copper should be thin pieces, like sheets or stranded wire.
                                        Electrode nuggets may take forever to dissolve.

                                        A hydrometer is not for measuring humidity, that is a hygrometer and
                                        many people are simply mistaken.

                                        A hydrometer is used to measure fluid density, it is a glass tube,
                                        with a weight at the bottom end and a scale at the top end. The higher
                                        the hydrometer floats the denser the liquid is and you can read this
                                        on the scale (the water line is the pointer). The ones sold to test
                                        car battery acid cost only like 2 eur and are just about sufficient.

                                        I recently bought a refractometer from china, for like 20eur. It is
                                        also designed to measure car battery acid, but it tried it with
                                        etchant and it seems to work. The refractometer is an optical
                                        instrument where you place a drop of liquid on a prism and the
                                        refraction coefficient is measured (Brechungsindex for you). You look
                                        into it like in a telescope. It is very quick, accurate, and less
                                        messy than the hydrometer in my opinion. But it does measure optical
                                        density, not physical density, as long as the two correspond there is
                                        no problem though. Also, of course, it is a measuring instrument and i
                                        just had to have one, no matter what.

                                        You only need the hydrometer to see how much copper there is in the
                                        etchant. There's an ideal density range for this etchant where you get
                                        the best speed.

                                        Another analysis tool you should have is a way to determine the HCl
                                        concentration in the etchant. This can be done by titration with NaOH
                                        and methylorange as indicator. That's actually quite easy to do, but
                                        not really needed that often.

                                        Bubbling, yes you can use it for regeneration but that is dead slow.
                                        H2O2 is more efficient. I just use bubbling to agitate the etchant so
                                        it is quicker and more even. You definitely want some form of
                                        agitation, CuCl is not the fastest etchant if you do not push the
                                        chemical parameters into the ideal range.

                                        ST

                                        On Tue, Jan 6, 2009 at 10:02 AM, Markus Zingg
                                        <homebrew-pcb@...> wrote:
                                        > I would like to switch to cucl for a while cause having a solution that
                                        > lasts virtually for ever seems to be very beneficial. Besides, I'm just
                                        > before building a new etching tank and thought that this would be a good
                                        > moment for a switch of the etchant too. Since english is not my native
                                        > language, I always felt a bit unsure if I understood things correctly if
                                        > you guys were talking about cucl in the past, and there were always some
                                        > open ends. In particular the following things are not yet clear to me:
                                        >
                                        > So, one would i.e. need to build 3l HCL/H2O2 and put in half a pound of
                                        > copper into it? Correct?
                                        > How many HCL and H2O2 to get to a 3l solution to start with? I mean
                                        > what's the ratio of HCL to H2O2?
                                        > Any restrictions regarding the kind of copper? I do have copper left
                                        > over that I use for the anodes in my through plating station. Would that do?
                                        >
                                        > Then, Stefan wrote " If you want to measure this, you can get a
                                        > hydrometer. The ones sold for car battery acid checks will usually do. A
                                        > refractometer should work as well."
                                        >
                                        > A hydrometer - when useing google - seems to be a device to measure
                                        > humidity? Correct? What is a "refractometer", which of the two would be
                                        > easier to get and where, and how would one measure what? Regarding the
                                        > "air stone bubbler", I think I remember that one uses this to regenerate
                                        > the solution. If so, does one have to do this every once in a while, or
                                        > only during etching, or just before?
                                        >
                                        > I'm sorry if these are dumb questions, but since working with chemistry
                                        > might be dangerous I want to be very sure I understand things correcly
                                        > bevore I start to experiment.
                                        >
                                        > TIA
                                        >
                                        > Markus
                                        >
                                      • Markus Zingg
                                        Stefan, Thanks for your information. Still some more questions :-) - Can you give a ratio to at least start? I mean how much HCL and H2O2 should I use for the
                                        Message 19 of 22 , Jan 6, 2009
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                                          Stefan,

                                          Thanks for your information. Still some more questions :-)

                                          - Can you give a ratio to at least start? I mean how much HCL and H2O2
                                          should I use for the first "run"?
                                          - Do you have a link to the refractometer? Cause at that cost, I
                                          probably also would apreciate to avoid the mess involved with a hygrometer.
                                          - what refraction coefficient or fluid density ranges would be good for
                                          etching?

                                          Since I'm only makeing prototypes, I don't mind if cucl is not that
                                          fast. The Fe3Cl I used so far is also not that fast after a couple of
                                          boards. I'm more after a solution which etches evenly and where I don't
                                          have waste to dispose thereafter (or as few as possible).

                                          Markus

                                          Stefan Trethan schrieb:
                                          >
                                          > I can't actually give you the requested exact ratios since i built my
                                          > etchant bit by bit and do not know them.
                                          > However, i think you will have to do the same, since at least the H2O2
                                          > must be added gradually. At first there would not be enough Cu2Cl2 to
                                          > oxidise, so much of the H2O2 would dissipate.
                                          >
                                          > The copper should be thin pieces, like sheets or stranded wire.
                                          > Electrode nuggets may take forever to dissolve.
                                          >
                                          > A hydrometer is not for measuring humidity, that is a hygrometer and
                                          > many people are simply mistaken.
                                          >
                                          > A hydrometer is used to measure fluid density, it is a glass tube,
                                          > with a weight at the bottom end and a scale at the top end. The higher
                                          > the hydrometer floats the denser the liquid is and you can read this
                                          > on the scale (the water line is the pointer). The ones sold to test
                                          > car battery acid cost only like 2 eur and are just about sufficient.
                                          >
                                          > I recently bought a refractometer from china, for like 20eur. It is
                                          > also designed to measure car battery acid, but it tried it with
                                          > etchant and it seems to work. The refractometer is an optical
                                          > instrument where you place a drop of liquid on a prism and the
                                          > refraction coefficient is measured (Brechungsindex for you). You look
                                          > into it like in a telescope. It is very quick, accurate, and less
                                          > messy than the hydrometer in my opinion. But it does measure optical
                                          > density, not physical density, as long as the two correspond there is
                                          > no problem though. Also, of course, it is a measuring instrument and i
                                          > just had to have one, no matter what.
                                          >
                                          > You only need the hydrometer to see how much copper there is in the
                                          > etchant. There's an ideal density range for this etchant where you get
                                          > the best speed.
                                          >
                                          > Another analysis tool you should have is a way to determine the HCl
                                          > concentration in the etchant. This can be done by titration with NaOH
                                          > and methylorange as indicator. That's actually quite easy to do, but
                                          > not really needed that often.
                                          >
                                          > Bubbling, yes you can use it for regeneration but that is dead slow.
                                          > H2O2 is more efficient. I just use bubbling to agitate the etchant so
                                          > it is quicker and more even. You definitely want some form of
                                          > agitation, CuCl is not the fastest etchant if you do not push the
                                          > chemical parameters into the ideal range.
                                          >
                                          > ST
                                          >
                                          > On Tue, Jan 6, 2009 at 10:02 AM, Markus Zingg
                                          > <homebrew-pcb@... <mailto:homebrew-pcb%40shdesign.info>> wrote:
                                          > > I would like to switch to cucl for a while cause having a solution that
                                          > > lasts virtually for ever seems to be very beneficial. Besides, I'm just
                                          > > before building a new etching tank and thought that this would be a good
                                          > > moment for a switch of the etchant too. Since english is not my native
                                          > > language, I always felt a bit unsure if I understood things correctly if
                                          > > you guys were talking about cucl in the past, and there were always some
                                          > > open ends. In particular the following things are not yet clear to me:
                                          > >
                                          > > So, one would i.e. need to build 3l HCL/H2O2 and put in half a pound of
                                          > > copper into it? Correct?
                                          > > How many HCL and H2O2 to get to a 3l solution to start with? I mean
                                          > > what's the ratio of HCL to H2O2?
                                          > > Any restrictions regarding the kind of copper? I do have copper left
                                          > > over that I use for the anodes in my through plating station. Would
                                          > that do?
                                          > >
                                          > > Then, Stefan wrote " If you want to measure this, you can get a
                                          > > hydrometer. The ones sold for car battery acid checks will usually do. A
                                          > > refractometer should work as well."
                                          > >
                                          > > A hydrometer - when useing google - seems to be a device to measure
                                          > > humidity? Correct? What is a "refractometer", which of the two would be
                                          > > easier to get and where, and how would one measure what? Regarding the
                                          > > "air stone bubbler", I think I remember that one uses this to regenerate
                                          > > the solution. If so, does one have to do this every once in a while, or
                                          > > only during etching, or just before?
                                          > >
                                          > > I'm sorry if these are dumb questions, but since working with chemistry
                                          > > might be dangerous I want to be very sure I understand things correcly
                                          > > bevore I start to experiment.
                                          > >
                                          > > TIA
                                          > >
                                          > > Markus
                                          > >
                                          >
                                          >
                                        • Stefan Trethan
                                          This is the one i bought: I wish it had a scale just for specific gravity, down to 1.0. I
                                          Message 20 of 22 , Jan 6, 2009
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                                            This is the one i bought:
                                            <http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=230309376059>
                                            I wish it had a scale just for specific gravity, down to 1.0. I don't
                                            really care about the antifreeze scales.

                                            1.2 to 1.4 is pretty much the range you need, and 1.0 to 1.2 is
                                            interesting while you grow the bath. Luckily car battery acid operates
                                            in the same range which gives us easy access to cheap hydrometers.

                                            You MUST read these two documents from the links sections, these are
                                            the ones where the link still work:

                                            <http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html#analysis_SG>
                                            By our very own Adam Seychell, probably the best document about
                                            homebrew CuCl you can find.

                                            <http://www.xertech.net/Tech/CuCl_ech.html> Also quite interesting.

                                            Which should also answer your question about stating quantities.

                                            ST



                                            On Tue, Jan 6, 2009 at 12:51 PM, Markus Zingg
                                            <homebrew-pcb@...> wrote:
                                            > Stefan,
                                            >
                                            > Thanks for your information. Still some more questions :-)
                                            >
                                            > - Can you give a ratio to at least start? I mean how much HCL and H2O2
                                            > should I use for the first "run"?
                                            > - Do you have a link to the refractometer? Cause at that cost, I
                                            > probably also would apreciate to avoid the mess involved with a hygrometer.
                                            > - what refraction coefficient or fluid density ranges would be good for
                                            > etching?
                                            >
                                            > Since I'm only makeing prototypes, I don't mind if cucl is not that
                                            > fast. The Fe3Cl I used so far is also not that fast after a couple of
                                            > boards. I'm more after a solution which etches evenly and where I don't
                                            > have waste to dispose thereafter (or as few as possible).
                                            >
                                            > Markus
                                            >
                                          • DJ Delorie
                                            ... Well, that s what I did. ... Assuming you re using 37% HCl and 3% H2O2, it s two parts H2O2 and add one part HCl (always add acid to water, not the other
                                            Message 21 of 22 , Jan 6, 2009
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                                              Markus Zingg <homebrew-pcb@...> writes:

                                              > So, one would i.e. need to build 3l HCL/H2O2 and put in half a pound
                                              > of copper into it? Correct?

                                              Well, that's what I did.

                                              > How many HCL and H2O2 to get to a 3l solution to start with? I mean
                                              > what's the ratio of HCL to H2O2?

                                              Assuming you're using 37% HCl and 3% H2O2, it's two parts H2O2 and add
                                              one part HCl (always add acid to water, not the other way around).

                                              > Any restrictions regarding the kind of copper? I do have copper left
                                              > over that I use for the anodes in my through plating station. Would
                                              > that do?

                                              Any copper should do. Any "tarnish" comes off really fast as it's
                                              pre-oxidized.

                                              > A hydrometer - when useing google - seems to be a device to measure
                                              > humidity?

                                              That's a hygrometer. A hydrometer measures the density of liquids.

                                              Alternately, just weigh 100ml of solution; it should weigh 120-130 g
                                              when you're done (plain water weighs around 100g).

                                              > Regarding the "air stone bubbler", I think I remember that one uses
                                              > this to regenerate the solution. If so, does one have to do this
                                              > every once in a while, or only during etching, or just before?

                                              I run it during etching, because it also stirs the solution and helps
                                              keep the etch even. Otherwise, run it whenever the solution starts to
                                              turn brownish.
                                            • kabowers@NorthState.net
                                              ... As to hydrometers; it might cut down on mess to remove the bobber from the tube and just drop it into the container and leave it there all the time. It
                                              Message 22 of 22 , Jan 6, 2009
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                                                On Tue, 6 Jan 2009 13:03:47 +0100, you wrote:

                                                >This is the one i bought:
                                                ><http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=230309376059>
                                                >I wish it had a scale just for specific gravity, down to 1.0. I don't
                                                >really care about the antifreeze scales.
                                                >
                                                >1.2 to 1.4 is pretty much the range you need, and 1.0 to 1.2 is
                                                >interesting while you grow the bath. Luckily car battery acid operates
                                                >in the same range which gives us easy access to cheap hydrometers.
                                                >

                                                As to hydrometers; it might cut down on mess to remove the "bobber"
                                                from the tube and just drop it into the container and leave it there
                                                all the time. It would also allow one to keep track of concentration
                                                all the time 8:)
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