Mushy impression (is it the plates or the packing?)

I’m confused here..

I’m printing with crane lettra with the deep relief base from boxcar. For some reason i’m getting mushy impressions (ink smush (not like ghosting) its like the rivers in the plates arent deep enough?

So far I’m guessing it may be when I use photopolymer plates from a local supplier and NOT boxcar’s - wtf? does the base know??

Its either the plates or my packing.. is there some kind of rule of thumb when it comes to packing.. hard stuff for some jobs? soft stuff for everything else?? Whats the best stuff to use to get a really good impression on Crane Lettra Cotton paper?

My pressblog has better pictures: you can see exactly what i’m talking about and has more information :)

image: tympan.jpg


image: cranepaper.jpg


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sorry.. i’m showing the impression made on the tympan when a page fell through.. its fine! what is going on??


looks good on the tympan, maybe you have too much packing. i’m no expert on polymer, but maybe the plate is too soft, i know there is some polymer that is softer, used mostly in rubber stamps, i’v used the softer polymer to print with a couple of times, but if you have just a little too much impression it wont print good. good luck dick g.

If you have smushed type as in too much pressure, you have too much packing. Photo polymer that is processed right with the exposure at the end is hard but can be smashed. Take out some packing.

Yes, I think too much packing. If you look at the topsheet you can see that the form debossed it quite a bit when it shouldn’t have left a mark. If there is going to be a deboss it should only be in the paper, and of course there is debate about that. The reason you got a better print is because the topsheet is a thinner, smoother, less absorbant paper than the Lettra and is also the thickness of the Lettra farther away from the form. Therefore the problem didn’t show itself as much.

Also, make sure you have a hard packing. There are times when a soft packing is appropriate but most of the time not. From the depth of the deboss in the topsheet I’m betting you don’t have any pressboard under it which I think would help a lot in addition to less thick packing in general.

Pulling an impression on the topsheet is actually a traditional way of setting the gauge pins, one I use all the time since it’s quick and accurate. But only the lightest impression is needed, just enough to get some ink on the paper. Keep in mind that you must take the thickness of the stock you’re printing into account when adjusting the packing. It’s better to start light and slowly work your way up until you get a good print or close enough that you can do any makeready that might be necessary.

Also keep in mind that the more sheets you add to the packing the softer it gets. And check it out before doing anything, but it’s possible the platen is a bit too far away from the bed and only thick packing will fill the gap and allow an impression. Probably not but keep it in the back of your mind when troubleshooting.


Front Room Press
Milford, NJ

There could be many different things making the print look as it does (or print at it does).
Without being there to pinpoint the problem, it is difficult to say. First I would take a loupe or linen tester (magnifying glass - usually about a 10x glass on letterpress press work viewing).
Take a look at the plate, the type face edges are they ragged under inspection? The plate made by anybody can only be as good as the negative given them. If a digital negative 2400 lines per inch makes nice and smooth type edges. The negative department used to sneak through 1200 lines per inch resolution negs sometimes, and it shows in the final product. Depends on what quality you need for finished product. Even with a minimal roller kiss to the plate, if the edges of the type on the plate are ragged, it is almost impossible to make a good crisp print, without the ragged edges showing.
That is one possibility of what it could be.

Other things are: (and the list goes on)
Rollers kiss to plate, too much ink, plate not anchored or kissed to base well, sheet hitting plate before impression, sheet dragging on plate after release from printing, packing not tight, tack of the printing ink to low and runny (tack should be around tack 13 usually if possible, depending on the sheet you are printing, perhaps a little less than that.

Are you sure that you have the correct plate? The deep bases take a thicker plate.

THank you everyone for your posts.. its a lot to troubleshoot. I’m thinking the plates are actually taller than the boxcar ones. I’m going to try with hard packing now and see if i can fix up this issue.. and if that doesnt work i’ll try your other suggestions. Thank you everyone!

I think your rollers are set too low. They are inking the side of the relief as well as the surface.

Check the roller pressure with a roller setting gauge and tape your bearers accordingly.

Daniel Morris
The Arm Letterpress
Brooklyn, NY

if your plates are taller then daniel is right, the rollers will be hitting the plate to hard.