Stipple effect on prints…help!

It might help if you could post a picture of your lockup so we could see how and where the plates are locked up in the chase. Also indicate which long edge of the chase is locked at the top, just under the ink disc.

Are the rails which the roller trucks ride on, nice and flat and even, with no pieces of tape or anything else on them?

Maybe the rollers aren’t hitting the plate completely. Did you try taking a sheet or two of packing out from under the tympan and put it in behind the chase?

Hi, I assume this press is new to you? First off I have to say I don’t know anything about deep impression as my training in letterpress printing forbade me to print with impression showing. However my suggestion to you is to get some smooth stock, repack your platen with a fresh packing and see if you can print your plates successfully. If not may be your rollers need looking at. An observation on your black printing, is this really suitable for the stock you are using? A good light weight card might be more appropriate, for writing on.

Thanks for the feedback… yes this is a new press for me, I’m an amateur. The rails are worn down and have strapping tape on them to get them to type height and I checked them with a line gauge. I took the packing out and barely got an impression. I’ve printed a few jobs previously with the same set up and had no issue with the ink stippling. I’ll add pictures of the chase now.

Is there something on your plate that’s repelling your ink?

When you took some packing out, did you put that same packing behind the chase, which would be between the chase and the bed? That would have the effect of moving the plate closer to the rollers, and so if the rollers weren’t contacting the plate well enough, that would improve the situation.

This is a plate to roller problem, are the rollers the same diameter all the way along? Is the track height level all the way along without the tape? Is the ink strip the same on your gauge at the top and bottom of the bed? Are the rollers skidding at any point? If everything is ok then as suggested underlay your form to raise the print surface towards the rollers.

I was able to get the entire plate to ink, but still getting a stipple effect on the print. I thought maybe there wasn’t enough ink on the plate and added more but only to have it bleed out the sides…still with an uneven stipple effect (that is the black ink photo) The only change is the garage is colder then when I printed previously…is it possible that the cold is affecting the print? Another note… we had to add more strapping tape to the right rail to get the roller height even.

Is there a dot pattern on the plate? If the art is RGB, or not 100% black, the image setter will print a dot pattern that will appear on the plate. You can also try a different ink and maybe rotate the plate.

No the plate has no halftime affect. The line is suppose to have dots but the letters are not. The letters are 100% black.

Where are you? A local printer might be willing to go to your shop and help you solve this.

Double post

“The rails are worn down and have strapping tape on them to get them to type height”

That’s an alarm right there- strapping tape will compress and it has a slick surface so the roller trucks can slide instead of rolling (do they?). There are various metal tapes that can be used to raise the rails a bit but I can’t point to one at the moment. How low are the rails and are they evenly worn? You may be better temporarily building them up with machinist’s metal “shim stock”, available at better hardware stores and some auto parts places.

I’d also change the lock-up so the plate is in a different location side-to-side, then see if the problem moves with it.

Is the platen actually level to the bed?

z!

You have good answers above. It does look like a roller adjustment issue. The cut marks look like they print on bottom part of the card but not the top. How cold is the weather and what type of ink was this. Ink contamination can cause issues but not like that generally. You can try putting some ink on the press and let it run for 5 minutes to mill the ink and adjust the tack to room temp to see if it will help.

Are you sure your stipple effect is not just the papers tooth?

From your pictures the checking in the paper matches the dots on your plate.

First thing i notice is you are hitting the paper pretty hard, are you sure you did not crush the edge of your polymer ?
A 12x18 can dump tons of energy into your plate and if the platen or your packing Is uneven hitting this hard something will give

If you flip your chase you see where the problem goes and that will tell you a lot

Second thing check to see if your packing is even

Third thing would be to make sure your platen is level

I see zero reason to tape your rails at this point

Are you reusing old packing? When you put that much pressure on the packing might get an indentation too and if you reuse it then parts of the image could drop out.

Is the ink pasty? Perhaps you might need thinner.

If you move the rollers slowly over the plate by hand can you see the plate image in the ink on the roller? Is the whole image there or are parts missing?

My own rule of thumb is to start with the least amount of ink and pressure to make an impression and add more as needed. I find issues and their causes are easier to spot that way.