Flood printing
I’m printing some business cards that have a solid color back on them. I did a short run test and managed to get a decent solid through two hits. What I’m concerned with as I embark on the larger run of 1,000 cards is how to make sure the backs don’t offset onto adjacent cards. I’m wondering if I’m better off running the front first, then doing the back last, so there’s less handling.
To trim the small batch, I slipsheeted so there was no issue there. I’ll probably do the same on the final run.
How do others handle this?
How many up?
What kind of press?
Hand or auto fed?
Deep impression on the front?
How much time do you have to let the first side dry, i.e. how much time do you have to do the job?
Thanks….this will help us make relevant suggestions.
Sorry, left out some details. Printing one up on a work and turn (i.e. two cards per sheet, but printing one at a time) on my Heidelberg 10x15. There’s imagery on both sides, so both sides need impression. Obviously, I expect the impression to get knocked back a bit from the opposite side.
I can let prints dry overnight or an extra day if necessary. Time pressure isn’t an issue.
I’m most worried about offset even from the delivery stack.
From way back,
*a* Slipsheeting as already implied, possibly with No. 2 as back up, (minders assistant).
*b* Small aftermarket Set Off spray, = (not Compressor style) small electric variety, triggered when on impression, hand fed or auto., with *Intergram or French Chalk*
*c* Look up your own, Van Son, 3 Way drier, Product V2155.? Read the spiel carefully.!.
When letterpress was King, the U.K. Method (fore runner of Van Son as above) was known as Paste Drier(s).
Should I run them in small lifts to minimize the weight from the paper stack?
When running heavy coverage:
Use a drier in the ink.
Keep the delivery lifts as short as possible.
If printing soft paper, you will probably need to slip sheet before cutting, unless die-cutting cards, and even then it may be required.
Reflex blues and purples are oftentimes the worst performers for setting off.
Cut in short lifts with minimal pressure to reduce set off.
Handle with care, and give plenty of time for the ink to dry properly.
The color is 151 orange and paper is Reich Savoy 236 lb. cover. If I didn’t have to run it through twice, I’d slip sheet it as it was delivered, but I can’t do it that way.
Try mixing CORN STARCH into the ink. We used that method when our powder sprayers went down. Or when heavy powder wasn’t enough to prevent offsetting.
It’s not a real dark color, so that’s lucky…..if there is a tiny bit of offset, it won’t be as noticeable as if the color were reflex or purple (as mikefrommontana said).
The fact that you are going to impress the inked image below the surface is probably going to be an advantage….it won’t be up on top where it would be more likely to contact the next sheet and offset.
When printing the second side, if you do start getting ink on the tympan from the first side of the cards, assuming the press holds good register, it should always be where the ink is supposed to be on the succeeding cards anyway, so that should mitigate that part of the problem. Because of this, I would set up the press to hold as tight a register as possible.
Run some extra cards so you can test the dryness of the ink before you print the second side. Rub the print against some unprinted paper (it could be Reich Savoy but could be any paper as long as it isn’t too smooth….photocopier paper is OK). Try to use a set procedure like 5 (or 10) rubs back and forth using the same amount of pressure. Use enough pressure so you do get some set-off at first. Do a series of tests after, say, 4 hours, 8 hours, 1 day, 2 days, etc. Then you can get an idea of how the drying is progressing. If you do this with other jobs, too, you will get better at evaluating the dryness of the ink and will become more educated as to when the ink is dry enough to back up the job, etc. (They make machines to test the rub resistance of inks. The most common one is the Sutherland Rub Tester. They are on eBay occasionally).
Also, I agree with all the other recommendations above.
Good luck and let us know how it turns out.
Jonsel.
Just for fun I am going to through another thought into the mix. In offset printing there is an effect called “gas ghosting”.
It occurs when the ink on one side of the sheet is not fully cured and the ink on the second side is fresh and giving off gases as it dries. In the lift the gases effect the way that the first side dries giving a reverse image of the second side copy on the first side. For years people thought this effect was from gas going through the sheet. This is not the case.
The most important thing that you can do to avoid this is to make sure that the first side down, whether it is the flood or the copy is adequately dry before printing the second side. If you print the flood second the gases from the flood can actually “re-open” the ink on the copy and take on the mirror image of the the copy onto the flood.
Drying is the most critical way to avoid this.
Since you mentioned a light color you are less likely to experience this, but it can happen in letterpress when a solid is involved in the same way it does in offset.
Of course it is also less likely to occur on an open and absorbent sheet like Savoy than on a smooth, matte or coated paper.
I would run the solid first, text second after the ink has had generous amounts of time to dry (a few days in a warm room).
Most of the time if I’m printing a heavy solid business card, I am printing on a 10x15 handed C&P and can double ink, or I can double hit without moving the sheet for heavy coverage.
I have developed a method that involves low piles stacked into a little box with tapered sides (I make this out of cardboard), and then drying upright in another box after I take the pile off the feedboard. I spray a little air in between the sheets in the ‘drying’ box after placing in there to set, this keeps a bit of space between the stock and has helped dramatically. Also, slip sheeting works but it doesn’t really help the problem of ink on the printed side being affected by scuffing, for example. The best thing to help with that in my opinion has already been mentioned- low piles, and drier.
Another suggestion I am not hesitant to offer- consider standing by the delivery with an air hose attached to a compressor (with a moisture filter), and blasting the delivery pile with small amounts of air at the bottom of the stack. This will help keep air between the sheets as you are printing and will help minimize contact between the sheets.
Additionally, you might want to run 4 up instead of 2 up. This could also help minimize contact. (Work and turn plus a flip or ‘flop’, so almost square press-sheets). If you’re running business card sized forms on a 10x15 this shouldn’t be a problem?