Quote Originally Posted by SloboM View Post
The blocking paper is placed right on the photo paper. I don't think that the light is penetrating art paper. It is 300 gr. in weight. Yes, during the last exposure entire sheet is uncovered and exposed for 5 sec. The print doesn't look like the last segment of the test strip. It is much lighter.
OK, so you 'think' that the blocking paper doesn't leak light, but we don't actually KNOW for sure.

Make your next test strip covering the print area with the photo paper box. It will not let any light through for obvious reasons. See if that makes a difference. Try that first.