Photopolymer plate takes time to ink

Sounds like a press problem, more specifically a roller issue.

Check out this previous discussion for possible culprits and let us know what you learn after you solve it:

https://www.briarpress.org/27580

Can we see a print..?

kittyj -
Your issue seems to point to roller pressure. You probably need to bring the rollers slightly tighter to the form.

An easy adjustment and remedy.

Michael

Are you sure you have enough ink on the press? Seems a silly question, but if five or six roller passes provide enough ink for a good print, a wee bit more ink might solve the problem. Better to be under than over, but best is just right.

Is it possible that the plate is a little low and the rollers aren’t making good contact with it? IME a lot of bases aren’t the right height (or the plate material isn’t).

I use KF152 plates (1.52 mm, 0.0060”) which need a 0.852” base; if you have a KF95 plate (0.037”) you need a taller base.

Never hurts to check the height; the shop micrometer gets a lot of use (checking plates, paper weight, sorting spacing material, etc).

Hi Kitty, I agree with adlib that you may not have enough ink. We used to have a rule in our shop that the proper ink level didn’t show until the 3rd impression. Then we could see if we needed to add or remove ink. The problem I see is if you’re printing some larger bold type, and some small fine type, there may be a conflict if you add ink to get the large type to print you’re going to have too much on the small type. You may have to break the form up, print the small type by itself then come back and print the large type. So, where are you on this project? How long a run was it? Are our answers helpful?

Hi everyone! Thank you for all your responses. I read them all last week and have tried your suggestions to troubleshoot my problem, but I’m still experiencing the same thing.

j archibald –
Thanks for sending! But I don’t think it’s helpful in my case because my plates are perfectly leveled and flat.

Nickel Plate Press, zbang –
I find this tricky because I already find my roller height to be good, i.e. my first print is perfect. I’d increase it by adding more tape on my rails, and I’d notice the rollers won’t even touch my plate. I’d remove a piece of tape, and the rollers would be too low that the ink would bleed when I pull a print.

AdLibPress, bppayne –
I took this into account, and had slowly added more ink than usual. At some point though, I realized that maybe it’s normal for the first sheet to be overinked and bleeding and that the subsequent sheets will be consistent (as frank hemmings has advised me in another post).

So I tried it anyway (now having added more ink than usual) and pulled 5 successive prints, and what I got were: the first print to be overinked, and the next 4 prints to get lighter and lighter, with the 5th to be just a ghost of a print. Shouldn’t it be consistent at least maybe by the 3rd or 4th or 5th?

At some point I thought maybe the formula could be decreasing roller height + add ink, but oh my, I’m still not getting consistently inked prints that at some point there would be no ink on the plate and I’d end up with papers with blind impressions. I had wasted a good amount of stock.

My diagnosis is the rollers aren’t inking the plate enough to catch up with the speed of the platen and the amount of paper that passes through. I already run on the lowest speed.

What do you guys think I should try next? Should I keep trying with the “decrease roller height + add more ink” solution?

bppayne, I’ll also definitely take your “proper ink level didn’t show until the 3rd impression” advice!

Sorry if my update is so long! I’m still so frustrated.

I’ve attached here several examples of my recent print jobs. I only have photos of up to 3 prints, but I should have taken photos of up to 5, haha.

(These are links. Can’t seem to upload them here)

(1) https://i.imgur.com/HkDyhQm.jpeg
(2) https://i.imgur.com/BgMcqYN.jpeg
(3) https://i.imgur.com/Y3blbwi.jpeg

Thanks to all!

The photos you shared have helped. Are you printing on Crane’s Lettra? Or something similar? Also, are you adding a thinner to your ink?

My hunch is you have your rollers too low or your ink is too thin. Find more in this discussion thread:

https://briarpress.org/19196

kitty, nice designs, btw.

i’m leaning towards the other comments that your first/second piece will be darker but this should be evened out by the third impression. i don’t think you either 1) have enough ink or 2) the rails are too high

you mentioned tape? you don’t need tape on a windmill.

can you please attach an image from one/both sides of the press that shows the rails and also the settings. i’ve included a sample image here.

https://prnt.sc/-8rRjnxhiktN

What ink are you using (and how old is it)? Have you tried others?

I’ve run into problems recently with a couple cans of rubber-base ink that are quite stiff, they don’t spread well or stick to the rollers. Usually a drop or two of boiled linseed oil and working with an ink knife will deal with that.Other cans of RB have been fine as have the oil-base ones. (This was on a Challenge Gordon, so a very different inking system.)

While it’s a pain to wash the press and re-ink, that may be a good test.

Because I don’t think you have done it so far, have you tried a different plate material? The surface properties of the plate have to be such that the plate will efficiently pull ink off the rollers, and then the paper will pull the ink off the plate. Sometimes this relationship can get messed up, because of variations in plate exposure and processing, or in batches of plate material, or even in the condition of the roller surfaces. Just to rule out the plate, can you lock up some metal type or a metal engraving and see how that prints?

After the plate has made a print, is most of the ink gone from the plate indicating that it has been efficiently transferred to the paper?

After the rollers have re-inked the plate, is most of the ink gone from the rollers (at least the first one) where the impression surfaces of the plate have pulled it off, indicating that the ink has been efficiently transferred from the rollers to the plate?

Just something new to think about…….hope it might help.

Hi everyone! Sorry for the late update, but after much printing and experimenting, I’ve discovered my solution: to be brave with adding more ink!!!

A little cheesy I know, but it was my weakness to be anxious about overinking and wasting stock that I’d make the first pull as my point of reference for how well the amount of ink is running on the rollers.

Eventually I did not rely on the first pull and relied on the 4th and 5th, until I saw that they were consistent by the 10th. That was when I gauged whether to add more or find a fix to lessen it.

And then when the impression would look good to me already, I’d let the machine run on its own. I was able to run a good stack of 100 of my holiday tags in half the amount of time it took in that makeshift method I did last time. Got to go home while the sun was still out, haha.

The silly old problem all along was me haha. Thank you all for your help, tips, and encouragement! I still have a lot to learn, so patience is the most important tool I’m trying to learn here :)