Thanks to everyone who wrote about home units for exposing polymer plates.
The workshop was on Saturday, so I didn't have time to build a home exposure
unit. I had bought a 250w photoflood bulb just in case the weather forced
us indoors. I had no idea of the exposure time, but it probably would have
been quite lengthy. Anyway, the weather cooperated nicely for us to make our
exposure outdoors in bright sunlight for two minutes (I think it actually
got up to 30 that day, a veritable heat wave around here...) I could not
have asked for a more successful trial, and this was using a very quick 'n'
dirty "negative" made by running transparency film through my laser printer.
The workshop participants were suitably impressed as we proofed the plate
and found it identical to the original (small squiggly lines). It worked so
well it was a little hard for me to make the usual case about how one can
do home processing for experimental stuff, but one really needs to have
plates made professionally for consistently fine detail...
Now that the workshop is over, I'm going to build my own home unit. I have a
vacuum frame that was given to me ages ago, but it no longer has the vacuum
motor. Any idea where I can get hold of that?
Ars Brevis Press
> From: "Rodney Grantham <granthams@...>" <granthams@...>
> Reply-To: PPLetterpress@yahoogroups.com
> Date: Mon, 27 Jan 2003 17:12:42 -0000
> To: PPLetterpress@yahoogroups.com
> Subject: [PPLetterpress] Re: Polymer Home Exposure
> --- In PPLetterpress@yahoogroups.com, Kent Manske <kent@p...> wrote:
>> Rod, your info to Katie was informative.
>> I have not had the short exposure times that you have with the
>> F20T12BLB, 24", 20 watt bulb. I just build a box with 6 tubes.
>> both A&V and Boxcar plates, my exposure was more like 10 minutes
>> hold 6 pt Bodoni serifs with hand wash) and 25 minutes to get step
>> on a Stofer (?) scale.
>> A phone call to Phillips informed me that the BLB (purple
>> has a uv filter on it. Their BL (white tube blacklite) does not.
>> just ordered the BL bulbs and will run more exposure tests next
>> weekend with hopes to reduce the required exposure time.
>> Phillips F20T12BLB, 24", 20 watt bulb (purple blacklite), available
>> at Home Depot and Wallmart.
>> Phillips F20T12BL, 24", 20 watt bulb (white tube blacklite),
>> available at Bulbs.com
>> Rod, let me know if you think I've errored somewhere in my process.
>> Thanks, Kent
> Hi Kent
> The difference in exposure times could be due to several
> variables. The distance from the bulbs to the plate, the
> voltage supplied to your bulbs and the type of plate
> material. We have our bulbs about 3" from the plate. Line
> voltage effects exposure times. On a dedicated circuit,
> so there is no voltage variation, our line voltage is 119.
> We are using a metal backed sheet polymer from the Louis
> Melind Company.
> If the specifications supplied with your plate material
> recommend a step 16 on a 21 step Stouffer platemakers
> guide, your setup may need a longer exposure. Sounds like
> you're on the right track.
> From our experience with photopolymer there is no difference
> in exposure times between the BL or BLB bulbs, in fact
> there is also a 350BL bulb. The numbers are the same
> on Phillips, Sylvania and GE bulbs.
> On another note, we also have a NuArc fliptop with carbon
> arcs and have found the exposure times need to be about
> 4 minutes with this material.
> Rod Grantham
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