Published: 06 September 2026 by Dan Williams
Stamp Articles
From the front, this 1971 Scotland 3p ultramarine Machin looks much like an ordinary example of SG S16. View the back of the stamp with an angled light source and the horizontal ribbed paper becomes clearer. The image below shows the difference: a normal-looking printed face, and a pronounced, textured detail on the reverse.
The unmounted mint example shown here comes from a part sheet from Cylinder 8 no dot. Although this doesn’t establish that the ribbing was confined solely to that cylinder setting.
The reverse photograph uses oblique lighting which picks out the ribbing quite well, in alternating light and shadow. Presenting a stamp angled towards a light source can often be a useful way to examine structure, and spot other features, rather than looking at it under flat, direct illumination.
The cause of the ribs isn’t directly known or proven here. During the manufacture of stamps there’s a finshing process called calendering, in which the paper passes between rollers to produce a smoother and more consistent finish. A roller-related effect is my best guess and an explanation for these ribs, likely due to a pressure problem, although I cannot guarantee 100% this is the exact cause for this particular variety.
Examples with sheet margins intact can sometimes be more useful for collectors. The ribbing can be seen from the front in the unprinted margin, although not quite as prominently as the reverse, whereas single stamps are best viewed from the reverse.
Apollo’s Lots Stamps has singles of the 3p Scottish ribbed-paper variety available on eBay. Examples with sheet margin are sometimes available. If you cannot find one listed, please get in touch.