how do i make a negative for photopolymer plate?

… is it as simple as printing the image/text on any laser over head transparency, Dianne Longley mentioned something
“Agfa Copyjet transparency film” i cant seem to find it and am now confused.

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Mai……. no, it’s not that easy. I’ve gone the Laser/Transparency route, and while it can be made to work, it’s not the best route. The problem is that the black is not 100% dense, and you wind up retouching a lot of the negative.

From my point of view, the only good way to do it is in a darkroom…… or to have someone who has a darkroom do it for you. In most cities there are still printers who use old-fashioned chemical film, and most will make a negative for you at a low cost.

Also, many PP plate vendors will take your art and make the negative for you.

Inkjet film solutions exist primarily to service the silkscreen market. Letterpress photopolymer plates require crosslinking to a much harder degree than silkscreen photopolymers, so if your negative is not opaque you will be letting light through to your non-image areas and hardening them.

Film is going to be expensive either way though. I have success printing film through an Epson R1800, but I am printing on film specifically designed for the application with special inks as well as running all my files through a raster image processor (RIP) which can tell the printer to lay down a LOT of ink.

As I said, this does get expensive, probably about $6-8 for a tabloid sized sheet. I did just get some oversized film run at a professional place that was about 15” x 17” and it cost me $50—still quite a bit more expensive than running inkjet would have been.

If you want to print without a RIP on to standard transparencies I think you will have a tricky time. People have had sucess printing it out onto multiple transparencies and taping them together, but registering these can be tricky.

Depending on your location there should be a typesetting service or graphic design company that can output your digital file to film. Check your phonebook, or visit a small offset printshop and ask where to get film output. Winking cat is correct - if the film image must be dense for the image to work.

You mentioned that you are using a RIP to achieve the proper density, and that it costs you about $6-$8 a sheet.
If you haven’t already, you might want to look into having your RIP and printer properly profiled.
It could give you better results at a lower cost.

Mai, it actually is very easy to make your own plates at home. I use a standard Epson printer that you can get at Wal-Mart or Office Depot, Adobe Illustrator, and a film made for inkjet printers that actually costs less than regular transparency film you find in office supply stores. I am able to get a good plate using these items and a home made light box. I have been able to process my own plates with pretty good level of detail, I can get clear 14 pt text in many fonts and line work for most artwork is not an issue. Everything in my set-up can be bought at regular chain stores and there are no special items needed. I am currently using Printight water wash plates that I just washout in my kitchen sink. I dry the plates for a few minutes after exposure with a heat gun that you can get at Home Depot and then post expose the plates in my box again. I have had some printers around town see some printed items I made with plates I exposed and with type I set and made a light impression with and they all had a hard time telling the difference and some could not distinguish between the two. If you contact me I will share the information I have so far.

Good Luck, Robert

Hey rwarnoldjr, do you have supplier information that you can share? I’d like to try the Printight plate — might be better than the material I am using now.