Detecting watermarks

Is there a way to detect watermarks when the paper used is generally watermarked such as for many German notgeld, with watermarks being the way to distinguish types or variants. Many countries have special places on the paper where a watermark can be seen. I am not talking about them but where the whole sheet of paper has watermarks, not just a designated area.

I have been holding the notes up to a bright light in an effort to see watermarks but sometimes I do end up making more of a guess than a certainty. I have occasionally noticed when doing a higher resolution scan to pick up the blank sides of uniface notes that watermarks show. Would this work on sides with designs?

Stamp collectors can use watermark fluid in special dark trays but these trays are mostly too small for banknotes and would the fluid hurt the notes? There are also special expensive machines for stamp collectors but again viewing areas seem too small for notes.

Thanks for any information you can provide.

Will

Hm, the notes I own with a sheet watermark have a strong density difference resulting in quite high contrast watermarks.

I just use a led light and two stacks of boxes onto where I put my sheets and take pictures (a light desk would be the optimal solution).
Editing the contrast of the picture is also an option to get a better look at the watermark.

Quote: "Idolenz"​Hm, the notes I own with a sheet watermark have a strong density difference resulting in quite high contrast watermarks.
​
​ I just use a led light and two stacks of boxes onto where I put my sheets and take pictures (a light desk would be the optimal solution).
​Editing the contrast of the picture is also an option to get a better look at the watermark.
​

Yes, I have no issues. It might be important to note that:
a) it is possible that some banknotes made during the war may have had poor (or thicker) paper production (& the watermark may either be missing or just very light/difficult to view). I have found watermarks are typically easier to view with thinner paper
b) watermarks may be off register (or just part of the note) due to poor QC/cutting production costs (sometimes seen on notes going the way of hyperinflation)
c) soiled paper​ (stains) washing & pressing all may affect the ability to see the watermark
d) counterfeits won't have a watermark

Thanks for the comments. Looks like there is no sure way to spot the watermarks so I must continue to struggle with them, especially when the notes are heavily covered with designs.

Will

Can you give us an example picture?

Here are scans of the latest note I dealt with.



According to Colnect there are 6 possible watermarks for this notgeld. https://colnect.com/en/banknotes/list/country/559-German_Notgeld/series/244301-Frankfurt_am_Main/page/4 shows 5 of them.

Will

Are these already with backlighting? Because I also don't see any watermark and it could be a reprint.

This is with backlight. Still don't see watermark but I am sure note is not a reprint as I have several in various conditions and all have problems in seeing watermark, as do many other notgeld I have.


Will

The watermark is visible. There are several variations (& you will see that your note matches Gra: F16.6a or F16.6b) They're just a small diamond pattern which show almost like small oblique circles across the paper.

This looks to me like under-print or does Colnect use the same picture for nearly every variant?

Quote: "Idolenz"​This looks to me like under-print or does Colnect use the same picture for nearly every variant?

​Notgeld was local currency aimed at making money for the community. Cheaper paper (& less labour intensive watermarks) would have been used. I cannot comment re: Colnect's image sources but at least they have some of the variants listed. What I think may have been varied was the watermark extending across whole note or simply behind the actual design.