Tiny hairline ink marks
I have a Chandler Price 12 x18. We were printing some boxes yesterday and there were these mysterious ghost hairs printing onto the finished product.
Tiny little hairline ink marks. We cleaned everything down and started over but they were still showing up.
Does anybody know of, or heard of this happening. I am stumped.
I would have thought it was maybe a random hair that wouldn’t leave, but the hairlines were showing up in different places every time.
We finally managed to fix the issue with less pressure, but it would still happen occasionally. The lack of reason is really bugging me!
the edges of your plate? is your plate (or forme) also over-inked? it sounds like your rollers are inking the edges of your plate/die.
if this is consistent on everything you print:
1) you could have trucks that do not correctly match the diameter of your roller and you’ll need larger trucks
2) your rails are worn and you need to tape them to make up for that.
if this is only happening on this print run, you need to ease the edges of your plate/die:
with mag plates, you can file down the edges to eliminate those lines.
with photopolymer you can do the same or cut them at an angle with a blade. (to prevent this in the future with photopolymer, use a “deep-relief” base and thicker plates.)
*EDIT* just reread and saw that it was happening in different areas each time. If it didn’t always correspond with an edge, then my comment is no help to you
This is just a guess from an experience many years ago printing cast coated board for a book cover. The board had been cut in house and it would appear the cutting blade was not at it’s best so some of the coating was being broken off. The air blast from the feeder was then moving the coating into the stack and would show up on the printing. To overcome the problem the trimmed card edges were wiped over with a cloth slightly dampened with glycerine, which being sticky would pick up the dust or fibres, it seemed to work pretty well.
One property of ink is that it can be “long” or “short.” Long ink is like honey - it forms long strings when the ink is separated, for instance between the ink can and the ink knife, or between the plate and the substrate during printing. When printing, the strings can be very fine, almost like spider webs, and they can adhere to the paper.
Short ink is like mayonnaise or butter - it doesn’t form strings.
To test if this is your problem, try a different ink which is a different consistency (even if it is a different color), or add something to a small amount of ink just for a test, to try to make it “shorter,” like one of the commercial ink additives, or linseed oil if that is all you have. If that solves the problem, then I would ask for a recommendation of an additive from your ink supplier, or ask for a recommendation here. I think there are better additives than linseed oil for production work. Linseed oil might affect the ink’s drying rate, etc.
If you have been printing from PP plates on a base, I would suggest it is possible a long piece of paper lint or a hair from a pet or other such contaminant could have ended up on the rollers. Sticks to the rollers, picks up ink- this ink moves to plate backing or base- and then the contaminating bit moves around, sticks to the ink disc, disc rotates, contaminating thing sticks to rollers in another spot, confounds you because little bit of ink ends up somewhere else instead.
Keep an eye out for little things stuck to your rollers next time you run that material after it’s been die-cut, could be your problem.