2 German Stamps Without Watermarks (?)

These two German stamps were issued in 1920-21, each of them in two versions featuring different watermarks.





Neither stamp was ever issued without a watermark.

German watermarks are among the easiest to see in the whole of philately - even in the case of used stamps. In the case of mint stamps, they're as obvious as obvious can be.

Example from allexperts.com:



However, these two stamps do not appear to have watermarks at all. Can anyone discern even the merest hint of a watermark on either of the stamps?





Anyone who knows German stamps knows what I mean when I say that these stamps are simply not normal!

Here are versions of the reverse sides of the two stamps that have been solarised. This process normally makes it easier to distinguish watermarks. However, in these two cases it seems to me that there is nothing to be seen!