Photo and Blacklight question

[Mark Mac]

I recently had some free time and wanted to test my photos with blacklight. I had two photos that I bought as postwar signed RK holders. I put them on the table as a test, knowing that they would glow. In that way I could compare them with the other photos I had purchased as originals.

Well, I conducted the test by laying out the two "test" photos and seveal of my originals. I was satisfied that the originals did not glow. Then I noticed that I could only see one of my "test" photos! It was glowing like Michael Jackson in a Pepsi commercial. Since I had place the photos over one another and overlapped them, I moved them to look for the second "test" photo. I found it and saw that it did not glow like the other postwar signed photo, but found that the blacklight had a similar effect on it as on the originasl.

Why would this be? I still do not think that the other "test" photo is original. Any suggestions? Here is the photo. Nice portrait of Otto Riess.

By the way, all my other photos refused to glow!

[R MICHAEL]

Well I would say the answer is obvious. The one that doesn't glow is either war time developed or post war using period photo paper. Either way sounds like you got a good'un Mike

[A.Capirro]

blacklight

Slightly off topic but I'm thinking of getting a blacklight.

Any recommendations?
Does the bulb's wavelength matter a great deal for examining paper?

thanks

[Tim DC]

Hi Mark

The blacklight test can not be trusted for a full 100%
There are some postwar papers that don't glow under blacklight, and there are some original photos which do glow under blacklight because of how they were treated postwar.