Levelling impression and packing on small platen presses

I was wondering if anyone on here could help me with a few queries I have on levelling/adjusting impression and the best method to calculate packing for my three small platen presses.

I have two tabletop Adanas (8x5” and HS/2 6x4”) and a Cropper Charlton & Co Peerless No.1 treadle platen press (8x5”) and I have always had issues with even printing and working out packing thicknesses and unfortunately they all need levelling.

I would like to print on stocks suitable for greetings cards/postcards and heavy stocks for coasters/invites. Ideally I would be looking to set all three presses up with the same base packing/impression that I could adjust accordingly for different paper stocks.

I was wondering if when initially levelling/adjusting impression on platen presses should the press be dressed with packing plus the thickest stock you intend to work with or with a bare platen?

I previously tried to adjust a platen to the bare platen and found myself with no room for a thicker stock to go in the press alongside packing without it being way too heavy of an impression. I also experimented with using an offset litho blanket and feel like it may have been too thick as my tympan was still picking up some ink when the throw-off level was down on my treadle press.

Any advice would be great as I have been reading through all of the impression/make ready guides I can find and I’m still having issues.

Thanks,
Kris

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On my two platen job presses, a Sigwalt Nonpareil tabletop and a Golding Number 11 treadle machine, I use a single thickness of offset rubber blanket under a single thickness of medium-thickness Mylar film. I have adjusted both platens so that with a couple of sheets of 70lb offset under the blanket a standard sheet of 20lb bond prints cleanly. If I want to print something thicker I can remove one or both sheets of 70lb. I almost never have to adjust the platens.

Bob

Thanks Bob, I may need to have another look at using the offset blanket again then.

Just to confirm did you adjust/level the press with the offset blanket and mylar on the press?

Kris

Yes, I leveled the platen with just the blanket and mylar under a sheet of oiled tympan paper, but it was adjusted to print a bit hard. That way most work will print cleanly, as the mylar prevents “punching” or making a deeper impression of the paper, but it “gives” a little if a type is a bit high and makes much makeready unnecessary for most jobs.

Bob

An interesting question for someone like myself who learnt the art of Letterpress printing in the 1960’s. Since retirement I now have a Heidelberg windmill and an Adana 8 x 5. The windmill has no adjustment relating to the type bed so is totally relient on the forme being type high an having the correct amount of packing including the stock being printed to 0.040 of an inch. So I will use a sheet of card, 2 tympan sheets and make up the rest with sheets of 3 thou thick. I have tried to set the Adana up in a similar way. I was taught to print with no impression showing on the back of the sheet and still work the same way, it makes the type last longer but it does take longer to make ready. I use to print sheets up to 35 x 45 inches and depending on the amount of illustrations could take up to 4 to 5 hours to get the press ready to run.

The essence is that clamshell platens of all sorts close like a book,.platen hinge does not adjust. There is a single plane
in space where the 918 high forme is truly parallel to the paper, whereby the job gets the same pressure at head and foot.That plane in space is critically located down to a thou of an inch or so. If you print airmail one day and board the next, to get back to that magical spot on plane you will have either to change the packing or if the press allows adjust the position of the press bed. I too was taught here in the UK that no impression should show on the back.