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13695Re: [PPLetterpress] Buying a Platemaker, advice needed.

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  • typetom2003
    Jan 24, 2014
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      Hi JP,
      Exposure time and time in the washout are the two most critical factors. Washout temperature not so critical. I use water comfortably warm to the hands but not hot; I use a hand-held hair dryer, and dry steel-backed plates until they are too hot to hold and then somewhat longer.
       
      (If they haven't been dried long enough they may still hold moisture that will eventually dry further and curl the plate, not a critical problem except for storing and reusing plates but they can be flattened again in hot water for printing again later).
       
      I have a homemade lightbox with four 18" bulbs, something like 2" above the plate material in an old NewArc vacuum frame. My lights are placed face-down on top of the glass. I found the vacuum was bending the glass very slightly and allowing irregular contact and exposure between the negative and the plate - matboard pieces to support the glass around the material solved all that. Funky system perhaps but routinely excellent plates can be done by hand.
       
      Trials and understanding what is happening in the process can get you there - UV exposure and changing of the polymer happen from the surface down toward the base; the UV light spreads as it travels past the negative into the material; unexposed polymer is water-soluble.
       
      (I do plates easily up to the size of cards and invitations, 4x6, 5x8; larger plates take longer with hand washout because you can't brush the whole surface at once - about 4 minutes in the water by my experience, it's time to stop).
       
      Best wishes,
      Tom
      Tom Parson/ Now It's Up To You
      157 S Logan, Denver CO 80209
      (303) 777-8951 - home & letterpress printshop
      (720) 480-5358 - cellphone
      typetom@...
      www.nowitsuptoyou.com
       
      In a message dated 1/24/2014 10:51:33 A.M. Mountain Standard Time, jp@... writes:
      Hi Peter,

      I've done a bit more research and decided that it would be better to DIY a quality UV exposure unit, than to pay for a cheap "All-in-one" platemaker.

      In your experience, are the KF152/KF95 plates very sensitive to factors like drying and washing temperature/time? If not, doing washing / drying by hand seems like a good way for me to start! 


      Some questions on your UV Exposure unit:
      -When you mention 4 sets of 2 T12 Damar bulbs, this gives a total of 8 x 40W = 320 Watts? 
      -How far apart are your bulbs from each other? I've read online that 2 inch (center to center) works well, but ideally I'd like to follow whatever works for you.
      -How far above the bulbs is the glass surface?

      Many thanks in advance :)




      On Wed, Jan 22, 2014 at 3:41 AM, Peter Nevins <nevins.peter@...> wrote:
      Guess it depends on the size of film, but i've sent you here pictures of the system that's been in place at the print collective i have joined.  I just jumped in and started using it and i've had no problems.

      Our setup:
      4 sets of 2 Damar F40 blacklights
      Heavy glass
      Various sized pieces of black foam
      Plywood enclosure
      A heavy weight, like 1/2 a cinder block, or in our case a litho grinding wheel.

      Best exposure time has been 10mins for kf152 and 8 min for the thinner kf 95.

      Don't forget importance of warm or hot water in rinsing

      S01500.jpg
      Shurline 'handipainter' foam handle paint brush works great for gently  washing out.

      Have fun!
      Peter

      Photos of exposure unit:
      1st picture: unit open with 2 pieces of foam. Plate and film under foam against glass.
      image.jpeg
      2nd photo: unit closed with weight.  The 2 pieces of foam have been chosen for thickness and even pressure.
      image.jpeg

      p.s. the unit has mainly been for silkscreen exposure but 3 or 4 more minutes and it's perfect for photopolymer.

      Ok!  ciao!


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      On Jan 21, 2014, at 9:33 AM, "J. Pow" <jp@...> wrote:

       

      Hi Peter,

      Thanks for the tips :) Starting off with a UV box sounds good.

      Do you have any pics of how you weight down your slides with the dark foam?

      Also, how many lamps does your UV box have? I've read that 6 x 25 watt is a minimum?

      Thanks,
      JP


      On Wed, Jan 22, 2014 at 12:22 AM, Peter Nevins <nevins.peter@...> wrote:

      Most important for me has been really good opaque film transparencies, a wide, soft, flat brush ($2.99 painting brush on flat styrofoam handle) and using warm/hot water to rinse!  I've just burned 10 in a row 12"x12" kf152 and kf95 photopolymer plates without losing one.  No vacuum, just dark foam weighted down on my uv fluorescent blacklight box.
      Have fun!
      P

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      On Jan 21, 2014, at 12:19 AM, <jp@...> wrote:

       

      Hi everyone,


      I am just starting out with home processing of plates and am thinking of getting a platemaker. 

      Ideally, I'd get a quality one, but given space and budget constraints,  I am thinking of getting one of the China/India type platemakers (3 in one, exposure, drying, washout).
      These range from USD1k - 2.5k. Alternatively, doing something DIY might cost me a few hundred dollars.

      As far as I know, the china/india machines' exposure units have vacuum sheets and are timer controlled. Washout units are typical (automated brush + water).

      --Is there anything in particular I should be looking out for / asking the equipment sellers?
      --Is exposure typically controlled just by time factor? Or are there are other variables such as lamp intensity etc that I should be considering?
      --Is drying process really important? Apart from time factor is it important to control heat temperature etc as well?

      I was thinking of going a DIY route, but that would probably set me back a few hundred dollars + time required to build everything up. I am not sure if DIY will also give consistency (given lack of vacuum screen, hand washing, hand drying). As such, going for a cheaper machine (USD1k range) might be a more viable option.

      Appreciate any tips / advice :)

      Thanks!





       
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