Hello,
I have a postcard with an address clearly written on it in pencil, but on careful inspection, I can see extremely faint writing, that appears light brown in places, but so faint as to be invisible unless you angle the card into the light. I believe this postcard was given to my mother by her putative father, and was probably stored with other letters etc by her mother until her death in 1976. So I was wondering if there was any technique to determining what the hidden writing is. Other than the address mentioned, the postcard appears to be unused.
Best wishes,
Paul.
