The ink set-off on the back is typical for flat plate printed stamps and rarely seen on rotary-printed stamps. This is not always 100%. Other indicators to tell the difference between flat and rotary is that rotary-printed stamps nearly always are imperfectly wiped so that there is excess ink traces on the face, whereas flat plate has non excess ink.
Enter if you dare into the dark hole of Washington/Franklins.
Mel (mbo1142)
Thank You
Confirms the flat & rotary difference.
The excess ink was new info.
Hi nl1947;
What you see is not bleed thru, but is contact transfer. This is caused because the just-printed
sheet comes off the press too fast and the one printed just before it is still wet. The one lands
on the other with the wet ink and it picks up on the back of the sheet.
It is kinda the way a rubber stamp works too. It is a long time on a rotary press for the ink to
dry to that when it does come into contact with the sheet ahead of it, the ink has dried. So yes
nearly impossible, unless the press operator did a whole bunch of things wrong.
Just chillin'....
TuskenRaider
The ink transference is a potential indicator, but not definitive. Size measurement of the stamp should still be made to confirm.
Flat plate printing is an engraved printing so the ink sits on top of the paper and can be felt, like raised bumps. Offset printing is completely flat, no raised ink. You can get a piece of real thin, not heavy duty, aluminum foil, place it over the face of the stamp, and gently rub with the pad of your finger. If it is engraved(flat plate), it will leave an image of the stamp embossed into the foil. Be sure not to rub the foil on the stamp.
just a slight clarification; Sean's explanation is great at explaining the diff between engraving and offset, but flat plate need not be engraved, in this instance it is. Rotary, for instance, can also be engraved. Rotary and Flat really describe one aspect of the plate (flat or round); offset and engraving a different aspect, namely how the ink is applied and the resulting texture on a printed stamp.
I hope I have not confused things
If you can see bleed through on the reverse, is this a fairly positive indication of the type of printing used?
re: Stamp ID - general question
The ink set-off on the back is typical for flat plate printed stamps and rarely seen on rotary-printed stamps. This is not always 100%. Other indicators to tell the difference between flat and rotary is that rotary-printed stamps nearly always are imperfectly wiped so that there is excess ink traces on the face, whereas flat plate has non excess ink.
Enter if you dare into the dark hole of Washington/Franklins.
Mel (mbo1142)
re: Stamp ID - general question
Thank You
Confirms the flat & rotary difference.
The excess ink was new info.
re: Stamp ID - general question
Hi nl1947;
What you see is not bleed thru, but is contact transfer. This is caused because the just-printed
sheet comes off the press too fast and the one printed just before it is still wet. The one lands
on the other with the wet ink and it picks up on the back of the sheet.
It is kinda the way a rubber stamp works too. It is a long time on a rotary press for the ink to
dry to that when it does come into contact with the sheet ahead of it, the ink has dried. So yes
nearly impossible, unless the press operator did a whole bunch of things wrong.
Just chillin'....
TuskenRaider
re: Stamp ID - general question
The ink transference is a potential indicator, but not definitive. Size measurement of the stamp should still be made to confirm.
re: Stamp ID - general question
Flat plate printing is an engraved printing so the ink sits on top of the paper and can be felt, like raised bumps. Offset printing is completely flat, no raised ink. You can get a piece of real thin, not heavy duty, aluminum foil, place it over the face of the stamp, and gently rub with the pad of your finger. If it is engraved(flat plate), it will leave an image of the stamp embossed into the foil. Be sure not to rub the foil on the stamp.
re: Stamp ID - general question
just a slight clarification; Sean's explanation is great at explaining the diff between engraving and offset, but flat plate need not be engraved, in this instance it is. Rotary, for instance, can also be engraved. Rotary and Flat really describe one aspect of the plate (flat or round); offset and engraving a different aspect, namely how the ink is applied and the resulting texture on a printed stamp.
I hope I have not confused things