I know a photog who tapes two 4x5 negs onto a 8x10 glass negative carrier using clear sticky tape (scotch tape) and then enlarges them onto a piece of photo paper. The tape does not show up in the photograph, but I have noticed that scotch tape does block some UV light and shows up in my carbon prints.
If one uses a thin mask on the same side of the glass as the neg (the same thickness or less than the film) pressure on the neg should give good contact. Using a material under the paper such as the closed cell foam, should also help to maintain good contact if there is a little thickness difference between the mask and the negative.
Putting the mask on top of the glass will also work -- but if the glass is thick, one may not get quite as sharp of a border around the neg.
But of course the best thing is to try it out a few different methods...best of luck!
Last edited by Vaughn; 02-07-2007 at 08:55 PM. Click to view previous post history.