I am having problems getting the correct inking coverage as well as impression for what I’m trying to print. I apologize if you’ve read about this on the letpress listserv or briarpress….I suppose I should’ve posted here all along.
I have a Universal III, and I am printing on 220lb Crane’s Lettra Duplex paper. If all I use is a mylar top sheet, then the print comes out fairly crisp. If you look at the photos, it’s the text on the right that is the problem. My rollers are set to 1/8″ right now. I (my client) want(s) a deeper impression, so I add some packing, and when I do that the text gets muddy. Can anyone lend any expertise here? I’m at my wit’s end! This is such a huge project, it will be 3-colors and the registration is tight around the hat.
I’m also wondering–is my plate set up incorrectly in that I should run the text separate from the art?
Thanks,
Carmela
So I have not read the comments on letpress/briarpress, but I thought I would throw my ink-knife into the proverbial hat with some advice.
I think the things Fritz and Paul have respectively said about the separate forms/runs/packing are definitely aspects of this to consider- but I am going to ‘roll out’ a suggestion about ink formulation as well.
Your typical letterpress ink is going to respond differently to various levels of pressure, and different amounts of ink applied to your rollers will also make a change as well obviously.
The more you pack, the deeper the impression, and the more ink spread/dot gain you’ll see- consequently, the more you pack, the less ink you need for some forms, and the tighter you want your ink to be.
It’s particularly evident in areas of small text and small detail, as you’ve described you’re dealing with, and these tend to web out even in areas which are isolated- lower case e fills in, your lower case i may look like a solid line, and the like. Lines broaden up to 100% wider if they’re very fine, as well, if the ink consistency is off.
The only way to modify ink to make it hold denser details is to add something to it which thickens it, causes it to be firmer.
If you’re using oil based offset style ink:
Body gum is an offset ink additive which does just that (though it should be added sparingly as it can transparentize denser colors if overmixed).
If you’re using rubber based ink OR oil ink:
Magnesium carbonate is a fine white powder purchased by the pound and can be used in both rubber based inks and offset inks, and provides a tackiness which allows certain details to show through though you might have added pressure.
I tend to make my inks too stiff and then to add litho-varnishes to them until they seem to be the correct consistency.
What Fritz got onto about the roller height in relativity to the base itself is not something to discount-
I am simply saying if you determine that the inking level is proper or re-set the inking heigh to the proper height, and continue to see the problems you’ve described even after changing out the press-packing, you might just need to stiffen up your ink as I’ve described in order to see the proper resolution with that level of pressure/impression.
I come from a printmaking background and feel that a lot of the time it was an ink issue, and not an ‘inking’ issue (as in, the properties of the ink, not the roller height/equipment) that needed to be addressed when I was attempting to print mixed forms on letterpress. Printing a lot of cuts at the same time as type was always a difficulty- a large area of coverage mixed with a crisp area of type is nearly impossible unless they’re the same height and the makeready/inking/form-height was perfect.
Good luck with your project!
I’ve followed this dicussion on letpress and I’m wondering what Carmela is using for packing on her Vandercook. When she mentioned that she washed up everything and then went back to try again and the results were worse, the thing that came to my mind is what the old time pressmen called “matrixing.” This is where a soft packing takes on the impression of the type and makes a matrix, the pounding of type forms on large cylinders regularly did this and print quality would dimish and then the packing would have to be changed out. Deep impression on papers like Letra seem to take a deep impression better when the paper fibers are compressed rather than being punched through the back of the sheet with the braille like appearance. So, not knowing what’s wrapped around Carmela’s cylinder, I’d suspect her packing is too soft and as she prints, the matrix effect deepens and the print quality gradually worsens.
What can be done? Carmella is already using a top sheet sheet of Mylar and that is fine, but then the packing underneath that Mylar needs to be hard as well, like regular tympan paper. I’m surprised that a single sheet of Mylar gives her a sharp impression where the cylinder undercut is .040–Letra is around .021, so I wonder what else is going on here. The figures don’t add up if the plate and base are at or near type high and this is not an adjustable bed press.
The other thought is that using a roller setting gauge is relative only to the bed of the press and not the type or plate and base being used, and if especially with photopoymer, the rollers need to also be set to what the plate/base combination actually are, and I’d suspect the plate/base combination is slightly over .918 and a 1/8″ ink stripe is too much. It is a lot easier to raise the plate/base by putting a piece of tissue or two under them to raise the plate to get more ink coverage than it is to keep fiddling with roller height.
Fritz
I see that you’ve received a raft of good advice on letpress and Briar Press. By now you know that you answered your own question about running the text separately. Two runs of the same color are nearly always simpler and faster to print than one form with both heavy and small elements, especially if it’s a mixed form with different bases, say lead type and polymer.