Carmen, I think it is overexposed. Last month I posted my result with my
first pigment tissue, and it is much like yours. If you don't get any black
color off the tissue, it must be highly overexposed. I exposed my negative
with just a regular light box (5000K, but not UV) for 5 minutes, and it was
already way overexposed. With UV, you could certainly use much less.
I suggest that you do a 3-min, 1-min, and 0-min (no exposure) and develop
them. With the 0-min, at least you should see the black oozing out as
described in books. If not, something else is completely wrong.
>> I thought I'd overexposed, so I tried several times with different
exposures, but the only thing I got was a very dark (almost invisible)
image on one of the tissues. >>
Was the almost invisible image recognizable? I did my first test with
Stouffer index and was able to recognize some letters from the index. Someone
on the list told me I should feel very happy about it because it took him
more trials before he can get an image. So don't feel too bad.
Funny that I am responding to this because I haven't got a chance to make my
2nd tissue and test yet, but I believe that even unsuccessful experiences can
help too, at least sometimes.
Good luck! And I will post my result when I get a chance to do my second
trial.
David S.