help with polymer plate printing
I recently switched to using a boxcar base with polymer plates (from magnesium on wood blocks), on my 8x12 C&P (old style).
I am struggling with getting the right impression— I have adjusted my roller height, (boxcar gauge as well), tried everything with the packing (hard, soft, mixed), tried less and more ink….
rollers are new, trucks are seam fine, I really am at a loss as far as what else to adjust….
See attached photo, it is part of a traditional wedding invite— I have been printing an address, one round on a flap for return, now I have moved on to printing on the front of the envelope for an RSVP.
I don’t want to blame the plate, but the current problem is a regular lightness at the top of one line of type in particular (see picture)
this same fall off happens to a lesser degree in the other lines.
I have moved the placement of the plate on the base, the problem is consistent.
It is almost as if the polymer is slightly resisting the ink (van son rubber based)- the whole letter looks this way when there is less ink applied— it almost beads up on the surface.
I am using Reich Savoy Natural White paper envelopes (80#)
any advice would be much appreciated!
thanks!
K&T.jpg
i think the picture did not attach the first time….here is the scan again.
nyny.jpg
Perhaps the photo was not of high quality, but the inking/print on the new york line does not look great.
Others have had a problem with poly plates taking ink. I have. I have pulled the chase and cleaned the form, turned rollers, said incantations and put the chase back in and it printed well. I don’t know which of the things I did worked. One should really only make one change at a time to see if that works.
Rubber ink does not like any oil at all. This can include a kerosene residue from a previous cleaning.
I suggest you pull the chase and give the form a dry rub cleaning. Pull one inked roller from the press and use it as a brayer on the form with the chase on the stone, or whatever you use for the flat place for the chase. If the form takes the ink well, you have ruled out an inking problem.
I have also used a pencil eraser on letters on a poly plate in an attempt to remove whatever might be rejecting ink. If you try this, do so lightly. You can damage the plate.
Hi, lindsay—
I can’t really make out what’s happening from the photo. But I wonder if your address line is printing over a seam in the envelope, so that part of the printing is on greater thickness and part on less, thereby receiving less impression.
Also, you can pull the form and look at the plate with a loupe to see if it seems uniformly inked.
Hope this helps, Brian
Agreed, it is hard to see what is happening in the photo. But I would bet the rollers are mis-set and are wiping the form as they hit it. They are probably either low (indicated by the filling of counter on the “k” and many filling angles) or over-inked. Photopolymer plates want a lighter roller setting than metal, and often lighter inking, and the relationship of track height to truck diameter to roller diameter must be refined or you will get roller slur; that is, the roller slipping as it passes over the form. What was adequate for metal will be problematic for photopolymer.
However, if truck and roller are not concentric, wandering light spots will appear as the appear in the work as the rollers are raised. Expansion trucks are particularly suspect here, but solid nylon tires can be made to roller diameter and put on the expansion truck body.
What will work? Some will suggest roller bearers. My experience with this problem lead me to build tracks up to near type-height, and trucks to near roller diameter. And I spoiled a lot of work until I came to that conclusion while experimenting with photopolymer on a C&P. Others here will disagree.
You mentioned that you moved the plate around on the base, did you also rotate the plate to verify that the lightness was oriented the same direction? That would help to narrow down the possible problems. If the lightness is still in the exact same spot then it is more likely a plate problem, if not it is probably something press related.
I can attest to the adverse affect of mineral spirits residue on a plate taking ink. The thumb sized spot that wasn’t inking was right where I had been holding the plate right after wiping something down with a rag and some mineral spirits. A thorough cleaning and drying made the problem go away.
Did you use the roller gauge specifically in the area where you are getting this problem (as close as you can figure at least) or just in the four corners? When we taped up our rails for the first time, the four corners all needed to be raised the same amount. This was fine when we were printing on the left side and middle of the chase, but when we had to print something on the right side we weren’t getting ink in a section. Upon checking the roller height again, found that the right side needed to have two layers of tape removed. After that it inked fine everywhere.
If it is a recurring pattern of lightness, I would concur that it sounds like a roller truck issue. If they are not even, the high spot would cause the roller to lift up slightly and therefore not ink well.
thanks for all your advice!
in the end I think it was because I wasn’t waiting long enough after cleaning the press before adding a new ink color. I use odorless mineral spirits for cleaning everything- rollers, polymer, ink plate.
I basically gave up for the night, then by the next day (ink left on the press) it had dried out a bit, and printed perfectly.
I changed ink color again, and though I gave it a very thorough drying off, still had the problem. again, letting the set up sit for 8 hrs resolved this.
Any other cleaning ritual suggestions? what other solvents are safe on rubber rollers?
If you give it a final wipe with naptha, (which is also called white gas and is sold as Coleman Lantern Fuel) the quick evaporating properties will reduce your turn around time from hours to minutes.
Paul
lindsay
There all a number of different possibilities for what is wrong here but if you cleaned your photopolymer plate with mineral spirits you sort of did yourself in. You need to use a fast drying, non-oily, solvent for photopolymer plates.
http://bielerpressxi.blogspot.com/2006/03/photopolymer-plate-longevity-p...
Mineral spirits, kerosene, press washes, Crisco, lard, Canola Oil, diesel fuel, Windex, (what else?) etc, etc., will cause you more pain than gain. Think it through.
Gerald
http://BielerPress.blogspot.com
Oh, I forgot, automotive anti-freeze, the current green solution for getting that oily first step “green” mess off your rollers. Doesn’t work well for that and does not wok well for cleaning your photopolymer plates.
Gerald
http://BielerPress.blogspot.com
California Wash seems to work fine for me.
ie, water miscible low VOC solvent.
Cheers!
peter
I would not recommend California Wash for cleaning photopolymer plates. It will be retained in the relief areas. And creep up into the surface ink, like any presswash.
Also, it’s not that low a VOC. It is banned in four California counties by last count. Can’t buy it in LA.
Gerald
We use Simple Green when cleaning our press and polymer plates. It MIGHT take just a little more time, but is so much better than California wash, doesn’t smell, and isn’t bad on your hands. And it comes in a squirt bottle.
Sometimes when switching from a dark color to yellow or white, we’ll do a final rub down with California Wash, but for the most part, Simple Green is awesome!
bethyq
You probably want to rethink using Simple Green, or other household cleaners as a press cleaner. Simple Green doesn’t have to list its ingredients (since it’s a household cleaner), but one of them is 2-butoxyethanol. How awesome is that?
Gerald
Nice that it comes in a squirt bottle so you can aerate the 2-butoxyethanol. It smells nice ‘cause they add scent to it to make you think it’s natural. It’s not.
Paul