Still A Little Confused On Printing Processes - Flat Plate Vs Offset

so the attached image shows some stamps marked with ' offset '. But , if I rub a piece of foil I get an image to show on the foil. From what im seeing, this should not happen on offset printed stamps, right?

All the stamps on your page are engraved, not offset. Engraved stamps can be printed flat plate or rotary.

Check the reverse of the stamps labeled offset. If ink present on the gum this would be called setoff often described as offset.






corrected: set off/setoff & off set/offset.

Ink on the reverse of stamps has been called "offset" for many decades in catalogs and by collectors. It has only been called "setoff" over the last few years by some collectors. Most still do not. There are only a small number of U.S. postage stamps that were printed by the offset process, although there are FAR more revenue stamps thus printed. While this difference can be confusing for some newbies, anyone with some reasonable experience should know which is being discussed in a given situation.

"There are only a small number of U.S. postage stamps that were printed by the offset process"

You have a very odd definition of a small number.

Yes, the intent should have led to stating,

"There are only a small number of U.S. postage stamps that were printed by the offset process before the Bureau of Engraving and Printing (BEP)'s preferred engraved process starting giving way to gravure printing in late 1960s--early 1970s." (See Scott 1355, 5c Biglin Bros. rowing & Sc. 1413a 6c Anti-Pollution on commemorative side; Sc. 1396 8c USPS emblem on regular stamp side.)

I can think only of the World-War I economy measure Washington Franklin offset regulars, and American Bank Note Co's "Overrun Countries" issues of early 1940s (printing of flag colors & nation's name) combined with recess engraved.

A giveaway to the intent of "offset" as used on this album page is obvious -- notations in same handwriting also regarding BACK of the stamps, not the printing. ("nh" = never hinged.) Reminds me of dealer's markings from run-through of an album for getting some estimate of value (buying or selling).

Photogravure and lithography are both similar to offset, but each has some differences. That's why they are not called "offset". Certainly they are more sophisticated then the offset W/F issues, but those and a few others are the only offset postal issues. And no one is going to confuse the modern issues anyway, unlike the W/F issues.

Are there people who care about wet ink getting (or not getting) on the gum of stamps?

Yes, there is ink on the back on all the stamps I've checked that have offset marked on the pages. Im familiar with offset as a printing process, but had never heard the term used to describe what you've mentioned, I.e, setoff..... Tks!

Yes there are, particularly if it involves most or all of the design in reverse. Which did occasionally happen. Not long ago I saw a 147 with a complete offset on the reverse.

"Photogravure and lithography are both similar to offset, but each has some differences. That's why they are not called "offset". Certainly they are more sophisticated then the offset W/F issues, but those and a few others are the only offset postal issues"

Gravure is significantly different than offset.
Lithography and offset lithography are very closely related.

@Stamps4Life,

Considering the page you show on which the stamp with the bell has the annotation 'offset' and the remark made by Germania; could it be that your confusion is caused by whether the stamp was printed by an offset technology or that the annotation points at an ink transfer on the back of the stamp? You might want to look at the gummed side of that stamp.

I think revcollector and eyeonwall made two good points. Maybe some of your confusion arises from what they pointed out.

Offset has two interpretations. Offset printing, often used with the lithographic process, is a way of printing stamps. Offset lithography has little depth, where engraving (especially the intaglio type) has ridges of ink transferred to the stamp. This is what you appear to hint at with the foil test.

An offset, also, can refer to ink from a source being transferred to a stamp. In philately, when sheets of stamps are stacked, and the printing ink has not dried sufficiently, or protective sheets are not inserted - there is another way this can happen but let's not complicate this too much - ink from an underlying sheet of stamps can be transferred to the back of the sheet deposited on top of it.

Both in the offset printing technique and in the case of the transfer of wet ink, wet ink is transferred. Hence, both are called 'offset.' However, from posts on this forum US collectors use set off to refer to ink transferred from one stamp to the other.

Thank you for your detailed explanation - as always appreciated…. There is ink on the back on all the stamps I've checked that have offset marked on the pages. Im familiar with offset as a printing process, but had never heard the term used to describe what's mentioned here as set off. All good now, got it.

Thank you from a bystander. These conversations are so enlightening for me. Now I have a question or two that maybe someone may shed light on.

I am studying a Canadian vending machine stamp booklet that was printed by BABN in 1979. It was printed on a web of paper but not cut into booklets right away. It shows set-offs on the glue. It was printed by "gravure" two colors (so a grey and a green cylinder), then a gravure cylinder with invisible (to the eye) tagging lines then a "chrome-plated steel engraved engraved cylinder" dispensing three colors to finish off. This is about the "set off" on the glue side. This was done in a continuous one color after another. These were not cut and deposited atop each other like sheet stamps. The colors that seem to be set off are from the "engraved" cylinder.
How do you get set-offs with a web of paper?

Normally, you do not.

What comes to mind is an incident when ink is deposited on the cylinder and no paper passes through the press. This would result in ink being transferred to a drum, when paper then passes through the press, it may cause an offset.

Someone once posted here this sometimes happened in Germany when a reel of paper was used up and a new reel of paper started. I could imagine when the reel tears apart or the press is started after maintenance, although the latter, usually, causes the missing colours.

Thank you NSK but maybe I need to show pictures.






The first picture shows the setoff or offset on the glue side. The second is a picture of the front. It is not always in the same position horizontally but always in line vertically. I have examples, enough of them, that I can start right at the top of the glue or start a bit lower all the way to the bottom.

Since these are printed on a continuous web and rewound on a spindle waiting to be examined then to be slit off and attached to the booklet covers I assumed that they were not completely dry and since the engraving ink is thicker and slower to dry, that when it is rewound, depending on the size of the roll (since the web is over 600 meters long) that it would fall on a different part of the back, always in a little different position.

Is this possible or am I barking up the wrong tree?