DIY Photopolymer Plates

We’ve been using the wonderful Boxcar Press for many years to have plates made, but wanting to have mockups made in real time with a letterpress can be slow and expensive if you’re trying to pump out content. After many youtube videos about the plate making process, it was time to take the plunge and test it out. Is DIY plate-making worth it, even just for proofing? Let’s see.

Boxcar offers sheets of unexposed photopolymer in various sizes, but to start out, we purchased some scraps. We ordered a pack of 94FL scraps here for about $25 to start with. To begin, you need to create a b/w version of your artwork in the same way you would prepare to send off to your plate maker. You then invert the image so the print will include everything that is not your image, i.e. a negative.

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You will also need printable transparencies, which I choose to use on a laser, for the ink coverage. Be sure that whatever media you use is spec’d for your machine. Ink jet printers will not work with laser transparencies, and will smear all over the place.

We find that it is best to print two copies of each and sandwich them together. This ensures the smallest amount of light coming through the black.



When your acetate is prepared, use a small piece of the unexposed photopolymer, peel off the bottom side, and place on top of the film, as if you were looking at the print, right side up. To expose, I used my exposure unit, though you can use a gel nail lamp for similar results, though I would sandwich the print and plate between acrylic or glass to ensure a flat exposure. I found that my exposure time is 160 seconds, and that works fairly perfect for most impressions. However, I have notices that smaller text and detail may need longer exposure time.

After the timer is off, in a warm water bath, the plate must be scrubbed with a minimally abrasive brush, for no longer than five minutes. I have found that the longer end of five minutes will prevent the smaller details from setting, and it will some off of the plate.

In the end, it works, and it works pretty damn well. The end result is not perfect, therefore it is not great for final jobs, but if you need preliminary proofs or samples, go for it!

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