3c Small Used Queen W/ Ink On Back

I've seen a couple of these with orange ink on the back. I read somewhere this can happen when the ink is still a bit wet and the sheet above is pressed on top. But I would expect to see that on the gum, and not on the paper itself. Unless they gummed after printing?

Just curious about how this happens.

The later 3c SQ used an aniline ink (vermillion colour). This ink tended to bleed through and is often visible on the back. The paper was not a very good quality either - thin.

What you are referring to is called OFFSET and occurs as you stated.

Hi JR

Small Queens were printed on dampened paper that was later gummed as a secondary process.

Stamps with offset images on the back are not uncommon and were frequently caused by a residue of ink on the press platen deposited when the press was inadvertently closed without a sheet of paper being printed. The next sheet was printed properly on the front but received an offset image on the back at the same time.

GJP

gportch, in all my reading I have never heard of that cause before, though it certainly makes sense.
The only cause I ever heard was the stacking of sheets when the ink on the sheet below was still somewhat wet.
Can I ask where you heard about this (if you recall)?