Windmill kiss impression inking issue

Hello PD-
You might want to try reversing the order of your packing and have the pressboard directly behind the tympan and the typing paper against the platen.
Typing paper does have a texture and that could be transferring to your image.
Good luck and let us all know what finally works for this.
Jim

jfitz,

Yes that is the way I do have it set up already, with the hardest pressboard surface just behind the tympan, and the typing paper behind the pressboard.

O.K. Another thing might be dirty roller trucks or tracks, if the rollers are skidding it creates a lot of issues
Make sure the poly plate is clean and dry before inking, maybe even try oil base ink.
Have you printed with this same ink recently? It could be old and need some tack reducer to have it flow correctly.

What do you use to clean the Printing Plate?

jfitz,
I think I’m cleaning the trucks and rails very well. I actually replaced the trucks today with new ones so will see tomorrow if that has made any difference. I do have some ink which is not so new, but have also tried brand new Van Son ink and had the same results.

typenut, I use odorless mineral spirits to clean the plates.

If the paper has a good deal of surface roughness, you may not have enough pressure to compress the surface sufficiently to transfer ink readily. There has to be a middle ground where you have sufficient pressure for ink transfer, but not enough to deform the sheet. Good makeready (building up the packing under heavy image areas, particularly) can help while not over-impressing light line areas.

Higher humidity also helps soften the fibers, but we generally don’t have much control over that in our pressrooms.

John Henry
Cedar Creek Press

I was not sure what ink color you are working with. Colors with high transparent white can be a problem. You are printing on 100% cotton you will need to flatten the fibers out somewhat to get a clean image. I use the lollipop for base setup but fine tune the rail setting for each job requirement. You may need a little more roller pressure. Before you add ink to the press with the rollers out or off pressure rotate the cylinder through little by Little wiping it down as you go. I find small amount of oil be be on the bottom part of the cylinder and when ink up it mixes with the ink. I use ZIP set soy base ink and never have any issues. I find it cleans up well and has a fine pigment. I never use rubber base except for numbering. If you sheet gets warped twist it back into shape. You can also use a taller pin just be sure is is away from your plate. Another thing to try is different press speeds. I never run above 3000 but have found at times if I try to run to slow the ink does no like to lay down as well. As rollers age they can start to crack, check the roller surface up close. Lastly I have lock out rollers so when inking up a new color I will add some ink and let the press run for 5 minutes. I want the ink milled out and up to room temp before I start.

Thanks for your comments jhenry and western 411. I’ve been trying different things to solve this problem off and on for several weeks so have tried inks both with and without opaque white (I never use transparent white) and really there is no difference. I will see if the new trucks help at all. One thing I found when removing the rollers yesterday was that both the bearings on the lower roller had come loose on the roller shafts. They are now pressed on correctly again so not sure if this could have created a problem.

I do tend to run the press fairly slow but will try speeding it up. I use rubber base because of my schedule— after I finish printing I need to leave the press for several hours before I can return to clean up, so I don’t want the ink drying on my rollers during that time. I could try the soy base ink if it would allow me that extra time to leave the ink on the rollers.

I do fiddle with a lot of makeready especially on solids, but as I mentioned this problem is apparent even on linework. I will experiment more with roller height— more ink/higher rollers vs. less ink/lower rollers. I don’t like to use too-heavy ink on linework because it bleeds over the edges of the photopolymer but perhaps I need to try and get more ink onto the plate.

I can also learn to live with more pressure if nothing else works. Thanks again for all your comments.

Mineral spirit is Petroleum based so greasy

https://www.boxcarpress.com/faqs/how-do-i-clean-my-photopolymer-plates-2...

Mineral Spirits are Petroleum based, so greasy:

https://www.boxcarpress.com/faqs/how-do-i-clean-my-photopolymer-plates-2...

Clean your plate right and start over

Seems that replacing the trucks was what was needed. After doing so the first few proofs I pulled, even before making any refinements, were remarkably improved, and I didn’t need to add any additional impression. An easy fix and wish I’d gotten them on there earlier.

I don’t think my inadvisable choice of plate wash was a contributor to this particular problem, as in order to eliminate old plates from the equation I’d tried printing with new plates I hadn’t yet cleaned, and was still getting the same poor results. But point taken, I will change to something milder.

I have found this thread really interesting, my first thought relates to the packing ! A tympan sheet, press board and a typing sheet, that doesn’t match Heidelbergs guide on packing at all. For jobbing work the packing comprises of 2 tympan sheets, 5 sheets of calendered newsprint and a sheet of ivory card, this is adjusted with the sheet to be printed to make up the 40 thou for packing thickness. In this modern day and age using polymer I sometimes replace 2 of the thinner sheets with a thin sheet of mylar which I place under the tympan but don’t forget you need a bit of give which is why we use packing in the first place. I’m one of the old school and only print kiss impression and try to match litho whenever possible. HAPPY PRINTING

I used a Zip Set Soy Based non skin overnight ink. In the cooler temp days and nights it will stay open longer. The comments about contamination to the plate or rollers from clean up products is something to consider. I have used some Gans products for many years with good results. Since you are working with a small roller train any source of contamination can effect your ink consistency and tack. I use a Gans plate cleaner to clean my plates and dab it clean afterword with a wet paper towel. I use a water soluble roller wash. Since it water soluble my last step is a water rinse so any left over product in cleaned away. I use a fast drying blanket wash for any chrome surface but not on the rubber rollers. I will still take a wet cotton pad and wipe everything down again. It is easier start clean than it is to guess what going wrong after the fact.

@printersdevil

Can you please tell me what diameter in millimeters these new plastic trucks are? Thanks a lot!

My calipers show 51mm

Regarding sheets falling behind the lay bar, if rolling the sheets still doesn’t allow bottom lay capture, try a light 45 degree fold along the the lay edge initially in one direction up to about 20 ml from the edge and then back the other way. This creates an X effect and strengthens the edge and is particularly useful if running lighter stocks like tissue paper. Another option if you are running a Heidelberg Press is to pull out the sheet smoother button which is near your pile height setting. You will also need the red/yellow plastic bar that is slipped onto the suckers to facilitate this. The only drawback with this tool is that sometimes the plastic bar can scratch colours laid down on a previous pass.

The other solution (if registration is not important) is to run the job “off lays”. The setting for this is above the grippers at the top of the platen unit.

The printing of solids on a platen can be tricky but one way we used to use when doing solids on A4 envelopes was to “double roll” the ink rollers. This was tricky and involved pushing in the impression handle and pulling out the feeder air suction, while the press was running the job, then letting the rollers go through a cycle before re-engaging suction and impression again for the second cycle. If the job is a long run your arms will feel very stretched by the end!

With solids it is important to reduce ink tack to a level that allows smooth separation from plate to delivery. If the sheet is bowing or not sitting flat on the platen then (if there was room on the sheet) we would use a Frisket Bar which was bolted to the rod next to the lay bar. This vertical bar could also be enhanced by a horizontal clip-on
bar to gain greater coverage of the sheet’s back edge thus holding sheet off the plate after impression.

Another trick that was used to help even up ink distribution was to lock up a horizontal type-high plate or 18pt leads, around 10ml x width of job, at job head, and first point of contact as rollers came down to image. This allowed the ink rollers to then roll more smoothly over job image. Vertical type-high plates/leads would also sometimes be used depending on job image.Good luck in your endeavours.