Checking Watermarks On Stamps That Are On Envelopes

I have an envelope with a pair of South Africa SG 35b on. Posted to the UK in 1947

The Stanley Gibbons catalogue has them valued quite highly for an inverted watermark. But how do I check that without taking them off the envelope?

For some reason they are CV at £50.00 (2009) for a pair used - and £1.00 for a used single. £650 for the inverted watermark.

Thank you.




*** Moved by Staff to a more appropriate forum. ***

I think one of Morley-Bright's watermark detectors may work on covers, but I'm the world's worst at locating watermarks!

Hi Eiger,

It can be a lot good photography, lighting and angles.

If the envelope has been opened from the top it will be easier to backlight the stamps. Do you have any of the issues from South Africa from the same time? It may help you in determining how easy the watermark is to see.

As for the catalogue prices, bilingual pairs have always been worth more than singles, since they began to be listed in the Gibbons catalogues sometime after WW2. I've often wondered why but can only suggest collector demand for a pair over a single.

Thanks Bobby. I saw in the SG catalogue that they had the CV for a pair but for the rest of the catalogue (99%) they only list the mint and used for a single, so I was surprised the had some showing values for a pair.

Geoff I tried the Signoscope and after a fortnight sold it back on ebay! Now I use lighter fluid and I have a reasonable (!) success rate.

Morley-Bright - the Roll-a-Tector, from memory - is a totally different product to the Signoscope, and a lot cheaper!

I haven't heard of that one Geoff, I'll do some delving

Also look into small very bright led lights, something that you can get inside of the cover. This light is several years old, there are smaller, brighter lights available.

They look very interesting! Thank you
And thanks for moving this to the right forum whoever did

Eiger, I notice you have a marginal copy on this cover. Put a few drops of lighter fluid on the margin and shine a good LED light through from the underside. This should sort it in about 15 seconds. You can buy LED lights with a USB connection for less than £5. Let us know the result whichever means you choose.

Thanks Tim I'll give it a go :)

Based on the usage date, I am wondering if the stamps are not SG 35b (which was issued in 1928), or more likely SG 46c (which was issued in 1936). The design was redrawn three different times, and all are pretty similar.

Look at the edge of the scroll on the right side and notice how the scroll is finished.
SG 35 has some shading in the area. SG 46 has a solid area and some shading, and SG 46c has a different look to the end of the scroll that is like two scroll ends meeting. If you have a Gibbons catalogue, they have pictures of all three variations.

I tried blowing up the image of your cover, but the resolution was too low for me to tell.

Most of the South Africa stamps from this time period were collected in pairs because one was in English and the other was in Afrikaans. Horizontal pairs are more highly prized than singles or Vertical pairs. So if you have a choice buy the horizontal pair.

As you look at most of these issues, you will see that SUIDAFRIKA is unhyphenated on the earlier printing and is hyphenated on the later issues. The 4d is an exception to this rule. So it is a little harder to identify.

I didn't have a scan to show you the difference between the 4d South Africa dies when I made my comment above. Here is a scan that should help you identify the various dies and the corresponding Stanley Gibbons Catalogue number.

Thank you KGVI :) Sorry for late response I am having computer problems!

I was talking to a laboratory technician about Lighter fuel and alcohols for detecting watermarks. He said the trace of Aliphatic content is not volatile and will remain in the stamp in microscopically small quantities. An anhydrous pure alcohol was his recommendation. Normal ethyl alcohol has a percentage of water. of course I'm talking about Chemicals in the UK, in the USA they might be made to different specifications.