US Scott #1289 G.c. Marshall Tagging On Hi-Brite Paper?

I was sorting through a pile of stamps and found a 1289 printed on what appears to be hi-brite paper. I have done a search and not found any mention of hi-brite paper used for this stamp. The photo below show the two stamps under shortwave UV. The possible hi-brite version is on the right. Both have overall tagging. Under longwave UV the paper on the stamp on the right appears bright white as well the left does not. Was this stamp printed hi-brite paper or is something else going on with it?

Mstocky, I left you a message under your other post.


Peter

Mystery solved. As promised I am posting new information on this. I ran it by Wayne Youngblood after his EFO class. He immediately indicated it was most likely caused by someone using a bit of dish soap during the soaking process to remove the stamp. He said dish soap cab contain optical brighteners and these can be picked up by the paper. Why dish soap in the soaking process, dish soap helps break the surface tension on item wetted down and can speed the process. I have checked numerous other used samples and found many that fully or partially respond like this under LW UV. Moral of the story don't use dish soap in the soaking process as it alters the stamp.