NuArc Platemaker conversion and exposing plates

For greater coverage I am posting on PPletterpress and Briar Press Discussions.

UPDATE: Platemaking experience with a NuArc FT18 platemaker.

Ok, so here is a recap and an update. I removed the glass top on the vacuum and replaced it with KREEN by creating a frame to hold it in and using the original hardware that was used with the glass plate. Until my 12 step gauge comes in I have a 14 step gauge that I tried to use but it really is no help

TEST 1: (6 - 3” x 3” pieces of polymer were exposed)
I started out with a unit of 17 which was about 00:01:45 for the test and run that up to a 79 unit exposure that was about 00:04:30. The longer exposure time increased the hardness of the plate but there was absolutely no shoulder to the artwork. I doubled the time for hardening. Commas and thin lines are weak but at the 79 units the plate is getting almost hard enough. At 99 units (approx 6 minutes) the letter forms bleed to a bold but shoulder thickness is still at a 90 degree angle to the artwork surface.

TEST 2: (6 - 3” x 3” pieces of polymer were exposed)
I purchased a DRAFTING FILM from the local art store. It has a frosted look but it is a smooth piece of plastic like material. I first taped it to the outside of the frame with a 1” gap between the FILM and the KREEN. With a 12 minute exposure there was very little hardening of the plate. Some letter forms even washed out during the first 3 minutes of hand washing the plate. Next I placed it between the KREEN and the NEGATIVE in the vacuum frame. I set the exposure to 99 and did another test. There is a very slight shoulder now and the hardness is getting better but it still is a bit soft even after the washout and hardening in the platemaker for 10 minutes without the film. The problems from test 1 are still there with the commas and thin ruled lines.

TEST 3: (6 - 3” x 3” pieces of polymer were exposed)
I added a second film for testing to see if it increased the shoulder angle. I did a timed exposure because the units stop at 99 and that is roughly 00:06:00 to 00:06:30 minutes on the bulbs current life cycle. I times an 8 minute, 10 minute and 12 minute exposure. The 12 minute exposure produced acceptable art without having the fonts grow to a bold weight. The shoulder however did not increase from the test 2 results with the increased addition of the extra sheet of film.

I even added tinfoil to the interior of the exposure unit in an attempt to reflect more of the light into the plate and broaden the shoulders but with no success. All it effected was the sensor for the interpolated (automatic) timer in which it turned it off quite soon after it was started due to increased light readings picked up.

I am at this point very open to more suggestions on ways to increase the shoulder width. Please let me know if anyone has heard of ways around this with and offset platemaker or if you know of someone I can talk to who has successfully converted one I would love to talk to them! I know that a Photopolymer platemaker has as bank of bulbs I however do not have the extra coin to purchase one. All I need is enough shoulder on the thin parts to do runs of 250 quantity with a reasonable impression in the paper.


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just a thought off the top of my head, I’m sure it’s completely wrong, especially since I’m not sure how your doing things now. From my days of table stripping films and making traps by hand, try exposing the film with the emulsion up, or so the emulsion of the film is not touching the plate. This is how we used to make traps. The light passing through the base (or clear plastic) of the film would allow it to bend outward. We used the frosted diffusion sheets as well which helped to bend the light. I have no idea if this will give you a shoulder or just fatten things up. Again, I have no clue what I’m talking about here, just guessing.

I figured it out! I had to make my own UV exposure unit that works quite well.

I have a bank of 6 black light tied together about 1.5 inches apart. I want to rework it when I have time to get them less than an inch but it is working great right now. With about a 3 minute exposure and a 5 minute washout by hand things are printing nicely.

If I am worried about the punctuation I post expose the plate 15 minutes instead of 6. Yes it does get a bit hard but for the short runs and immediate use it works really well.


Good work! At the art school where I work we have been experimenting with photopolymer using the silkscreen vacuum exposure unit we already have. We’ve been having a heck of a time washing plates out without deterioration. Details just seem to wash away before we can get things washed out correctly. Do you have any tricks for washout, or do you think our plates are just underexposed?

Daniel Morris
The Arm Letterpress
Brooklyn, NY

probably under exposed. Or your washout is too long or with a brush that is not soft enough. I spent about $70 on bulbs and fixtures. I attached them to MDF for the time being.

Using a black light bulb you don’t need to worry about the UV and your eyes like the white blacklight florescent bulbs. They might work better though.

Look through my flickr photos to see the quickly put together exposure unit.

Over the last couple of weeks I have learned how to make plates. While still crude it is working really well for what I need. With a hand washout I am limited to size of the plate produced. In time I can trade this method for a real photopolymer plate maker. But until I am able to drop $5000-$10,000 on a fancified machine I am going to keep doing things in this fashion. I iwill clean things up and make something more sturdy for am exposure unit.