Photopolymer backing showing up in deboss

Right now I’m just getting into designing photopolymer plates for debossing. I have done some on a tabletop platen press, and some on an etching press. I’m happiest with how much pressure I can get on the etching press, but in both cases, when I get the impression as deep as I’d like, it also begins to take the impression of the backing, as in the outline of where I cut the photopolymer plate out. I tried using layers of tape to sort of make a ramp, so that the edges aren’t as harsh, but it didn’t help all that much. I had left about an inch perimeter of the base around the image, should I have cut it closer? Is there any consequence of cutting right to the image? I’m really new at this and there has to be a solution. What am I doing wrong here?

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I think that just means you’re putting too much impression compared to the polymer. It’s not designed with that much relief. You could try Boxcar’s deep relief plates, or ask a die maker for an option with more relief to it.

Hey that’s good experimenting. I’ve never tried that with polymer, one because I don’t think it was designed for that, (it’s not all that rugged) and two because I think that to get a good emboss or deboss, I would use a counter. If I had a counter, I could remove material from around the image from the counter, and not the die itself, to get rid of those pressure marks from the backing.
So, if your using some kind of soft packing on the platen side of your make ready such as a thick paper I might tape that down to the platen with two sided tape so it won’t move, make an impression on it and then cut away the parts that cause the pressure marks I don’t want to see. Then you wouldn’t be cutting the polymer itself so you wouldn’t risk damaging it, but you might be able to fix the issue or get some ideas about what might work for you.
If you’re working on an etching press you might be able to carefully lay your packing material out, taped to a cover sheet, and mark it’s location on the bed of the press so that you could remove it and put it back into the same position. The plate would also need to be held in position. Then you might be able to cut out the non-printing parts of the image from the packing and place it back into position. If your currently just using a press blanket you might need to find a thinner one to accommodate some packing between the blanket and the plate.
Another, maybe easier idea would be to cut out some medium weight paper somewhat smaller than the plate and place it under the polymer plate. Then when you print the pressure would ease off when it got to the edge of the paper and not show at the edge of the plate. Also, you could try using a sharp blade and cut all along the edge of the plate at an angle so there wouldn’t be much of an edge.
… or perhaps someone who has perfected the process already could share how it can be done. I’m just sitting here thinking about this because it’s Monday morning and the stock that I need isn’t here yet and I can’t do anything but wait and I’m not liking it at all.

They are printing plates not intended for debossing. They will only give a slight indent into your stock not a deep deboss. For that you need a die to be cut or metal plate made.

Using the etching press is a much better idea than the tabletop platen for that kind of deep impression, so I recommend sticking with that. The platen press would be under severe risk of breakage with that kind of pressure.

You can definitely trim the excess photopolymer around the sides to as close to the image as you want, though if you go right up to the image bounds, you might get some warping or even a break at the edges.

Something that might help is dampening the paper prior to printing. This should allow you to use less pressure to get the same deep impression, so you’re not pressing into the backing. You can also try getting deeper photopolymer or metal plates made.

If you are using the deeper relief plates, the relief (from the carrier to the face) is roughly .050”. Various suppliers might vary, but that is close. So that would tell me that you could deboss close to that depth before seeing the edge of the plate on your substrate. The thinner plates are in the .030” range, so you would see the edge of the plate if you debossed to that point.

Use hard surfaces in your packing, and for maximum effect, just cut away the packing (make-ready) so you are only applying pressure close to where the image exists.

I have done significant blind debossing with photopolymer plates, so it is possible.

John Henry
Cedar Creek Press


Are you using felt blankets to run the impressions on the etching press?

If so, that will be likely to always leave you with some kind of plate mark. Felts are meant to ‘bottom out’ on the bed for thin plates like photopolymer, and this means you’ll see at least some mark-up from the backing plate.

The only way to truly get around this, is to have the plate made so the backing is larger than your sheet of paper, OR to ‘lift’ the impression areas of the plate with some carefully cut out backing material like mat board. You would stick this to the back of your polymer plate ONLY where your image area is to ‘lift’ the plate a bit, and then back the pressure off on the etching press of course. This would ‘raise’ the printing areas up a bit from the floor of the press and could solve your problem potentially.

(Disclaimer: didn’t have time to read all other replies, so apologies if this is repeating anyone else’s advice.)

Good luck.

Crown Flexo makes photopolymer embossing and debossing plates. We have tried them with good success. It was also a good coast saving way to make smaller grouped die sets. I put a couple of dies on the same page which would have cost more the they were mag or copper dies.

Sorry forgot to mention. First let me say I am not an expert but there are some smart guys in this blog who can answer this better than I can. A true debossing and not just a blind deep hit impression will have different results due to debossing using a counter to form and contain the strength of the image into a formed molded area rather than a blind hit made by just pushing image into paper.

I have to sometime something for a client, one was a large debossed sheet. Made 2 polymer plates, one relief, one negative with allowance for paper thickness, relief at bottom, dampen sheet on top, negative on top of that and than a run thru the etching Press, worked like a charm