Identifying the difference between a lithograph and offset print – or how I spotted few forgeries on spanish stamps
I was preparing some scans on unwanted (duplicate or mint) items for my stamp exchange website when I noticed few mint Spanish stamps that didn’t seem to fit into picture. The subnotes on stamp catalog confirmed my hunch- I had stumpled upon forgeries of somewhat common and cheap stamps.
The original issues were printed using lithograph (”stone printing”), the forgeries were printed using offset. I know many collectors struggle with how to tell these apart - especially if having nothing to compare with. In reality the difference is quite easy to spot if you know what to look for:
What offset usually means (especially post 1920’s stamps) is photogravure print, and it will ALWAYS show lines of dots (or beads) of color when looked at proper (at least 10x) magnification. The dots will be visible on both the outlines and fills.
Lithograph print on the other hand will ALWAYS have a somewhat solid outline and fill. In lithograph, the paper is flat and there will be no notable indentations differentiating design from non-printed areas (except maybe on the top).
However, if you feel the printed design from the back of the stamp, then the stamp is printed in typography (also known as letterpress).
Below are some images to tell the difference using visuals between lithograph and offset (photogravure) print.
First, here’s a real spanish stamp printed in litho. Notice how firm the borders and fills are.
Lithography - borders and fills are clear + solid. No dot pattern visible.
And then a forgery printed in offset (photogravure). The print is very unclear and there is a visible dot pattern especially on outlines.
Offset - the print is somewhat unclear and there is always a somewhat visible dot pattern.
Instead of going to trade, the forgeries ended up into my collection.
Knowledge is power!
Good eye Keijo!
Do you know how the dot pattern is created? Offset uses a rubber transfer plate/roller so I would expect it to be smooth. Is there a screen or mesh involved?
In modern offset printing (=photogravure), the dot-pattern is always there as image is build of very tiny dots with different colors (usually CMYK).
The image is etched using a photographic process (screening) onto the cylinder. This produces rows of dots, which make up the image. How visible the dots will be on final output, depends on (dot) density (which is usually 150 dots per inch or finer) and ink flow.
PS. I updated the original article a bit, as I know U.S. and European terminology of printing methods tend to be slightly different. This is especially confusing as different stamp catalogs use different (and sometimes even contradicting) names for same things.