Usually the difference is with the perforations. Water-activate gummed stamps will have "standard" perforations. Self-adhesive stamps will usually have die cut perforations. Also the perforation gauges between the two types are usually different. Sometimes the two types of stamps are different sizes.
The catalogs will advise of the differences between the different printings.
If you get stuck, post images of the stamps. You'll get some added help from people here.
US SAs are pretty easy, generally, to tell from their gummed counterparts. The former typically rounded die-cut edges where the latter typically have more traditional perforations whith smooth semi-circular holes but rough tips.
But remember those rounded tips may be a slightly different perf and the wavy shape itself may exhibit differences between printers. The Machins with an elliptical perf may in itself have a detectable different shape, a more or a less football (American) shape or the elliptical perf's location may be higher or lower.
When I'm in doubt as to whether a stamp is a self-adhesive stamp or not, I put the stamp under strong magnification and if I can see paper fibers on the ends of the perforations I know it's what I call a 'sheet' stamp, or water activated stamp that has come from a sheet.
Liz
I agree with Liz, the paper fibers left after two regularly perforated stamps are separated is the best tell tale, self adhesives always have a clean perfectly formed edge. And while in the subject, does lighter fluid affect the stamp if soak in it?
Tony
Most stamps - but not all! - are not affected by lighter fuel, turpentine, or other hydrocarbon solvents. However, there are some whose printing inks do dissolve in these. There may be notes to that effect in catalogs. Also keep in mind that these solvents aren't exactly good for your health, so do not use them too often.
Most glues of the self-adhesive kind do not really dissolve in hydrocarbon, but become soft and can be scraped off the back of the stamp with the edge of a ruler, a telephone card, or the like.
-jmh
Hi Stampbaby....
Sel Adhesive GB Machins are very easy to identify.
There are two identifiers to look for.
First there are the elongated oval shaped perfs near the bottom of both sides all self adhesive Machins have these. Ordinary adhesive stamps do not.
Secondly there are two oval shapes near the bottom corners of each stamp. These are there to prevent re-usage. If you can un-stick the stamp you will find that there will be two oval holes where these shapes are. They are cut through and designed to be left behind when the stamp is removed from the paper.
Hope this helps.
Kim
Even self adhesive pictorials and commemoratives have these marks.
I'm afraid I have to clarify a few things which otherwise may lead to confusion:
1) It is true that the self adhesive Machin stamps have elliptical perforations, but these perforations were already introduced in 1993 and have been used for "lick and stick" stamps as well.
2) All stamps with oval die-cut shapes as shown in the previous post (security features introduced in 2009) are self-adhesive, but there are older self-adhesive stamps without this feature. Self-adhesive stamps were also introduced in the UK in 1993.
3) There are self-adhesive pictorial stamps without any distinguishing marks other than being die-cut.
For 1) and 2) allow me to refer to the comprehensive website of Robin Harris at www.adminware.ca/machin.htm - for 3) the listings of new issues at www.norphil.co.uk/sitemap.cgi.htm (Norvic Philatelics) may help.
Hence if one wants to identify all self-adhesive UK stamps, it is still necessary to look whether the stamp is perforated (torn from a sheet, coil, or booklet pane) or die-cut. A magnifying glass of moderate strength will help with that.
Martin
Once cancelled and removed cleanly from paper with lighter fluid, I'm finding it difficult to tell the difference between "self-adhesive" from water activated stamps. The GB Machins and some of the smaller USA issues are especially difficult to tell the difference. Any identification suggestions will be appreciated.
Stampbaby
re: How do I identify cancelled Self Adhesive stamps?
Usually the difference is with the perforations. Water-activate gummed stamps will have "standard" perforations. Self-adhesive stamps will usually have die cut perforations. Also the perforation gauges between the two types are usually different. Sometimes the two types of stamps are different sizes.
The catalogs will advise of the differences between the different printings.
If you get stuck, post images of the stamps. You'll get some added help from people here.
re: How do I identify cancelled Self Adhesive stamps?
US SAs are pretty easy, generally, to tell from their gummed counterparts. The former typically rounded die-cut edges where the latter typically have more traditional perforations whith smooth semi-circular holes but rough tips.
re: How do I identify cancelled Self Adhesive stamps?
But remember those rounded tips may be a slightly different perf and the wavy shape itself may exhibit differences between printers. The Machins with an elliptical perf may in itself have a detectable different shape, a more or a less football (American) shape or the elliptical perf's location may be higher or lower.
re: How do I identify cancelled Self Adhesive stamps?
When I'm in doubt as to whether a stamp is a self-adhesive stamp or not, I put the stamp under strong magnification and if I can see paper fibers on the ends of the perforations I know it's what I call a 'sheet' stamp, or water activated stamp that has come from a sheet.
Liz
re: How do I identify cancelled Self Adhesive stamps?
I agree with Liz, the paper fibers left after two regularly perforated stamps are separated is the best tell tale, self adhesives always have a clean perfectly formed edge. And while in the subject, does lighter fluid affect the stamp if soak in it?
Tony
re: How do I identify cancelled Self Adhesive stamps?
Most stamps - but not all! - are not affected by lighter fuel, turpentine, or other hydrocarbon solvents. However, there are some whose printing inks do dissolve in these. There may be notes to that effect in catalogs. Also keep in mind that these solvents aren't exactly good for your health, so do not use them too often.
Most glues of the self-adhesive kind do not really dissolve in hydrocarbon, but become soft and can be scraped off the back of the stamp with the edge of a ruler, a telephone card, or the like.
-jmh
re: How do I identify cancelled Self Adhesive stamps?
Hi Stampbaby....
Sel Adhesive GB Machins are very easy to identify.
There are two identifiers to look for.
First there are the elongated oval shaped perfs near the bottom of both sides all self adhesive Machins have these. Ordinary adhesive stamps do not.
Secondly there are two oval shapes near the bottom corners of each stamp. These are there to prevent re-usage. If you can un-stick the stamp you will find that there will be two oval holes where these shapes are. They are cut through and designed to be left behind when the stamp is removed from the paper.
Hope this helps.
Kim
Even self adhesive pictorials and commemoratives have these marks.
re: How do I identify cancelled Self Adhesive stamps?
I'm afraid I have to clarify a few things which otherwise may lead to confusion:
1) It is true that the self adhesive Machin stamps have elliptical perforations, but these perforations were already introduced in 1993 and have been used for "lick and stick" stamps as well.
2) All stamps with oval die-cut shapes as shown in the previous post (security features introduced in 2009) are self-adhesive, but there are older self-adhesive stamps without this feature. Self-adhesive stamps were also introduced in the UK in 1993.
3) There are self-adhesive pictorial stamps without any distinguishing marks other than being die-cut.
For 1) and 2) allow me to refer to the comprehensive website of Robin Harris at www.adminware.ca/machin.htm - for 3) the listings of new issues at www.norphil.co.uk/sitemap.cgi.htm (Norvic Philatelics) may help.
Hence if one wants to identify all self-adhesive UK stamps, it is still necessary to look whether the stamp is perforated (torn from a sheet, coil, or booklet pane) or die-cut. A magnifying glass of moderate strength will help with that.
Martin