As I understand it the OP isn't ballparking at all. He is simply transferring the exposure of the best test strip to his full print, changing nothing else. He also seems to be working out his test strip exposures correctly and yet if he is doing it all as he says, I cannot work out why his full print exposure isn't right.
Something changes when he does the full print but what this is I now have no idea as he seems to be doing everything right.
I am completely puzzled
Indeed. This is why I was wondering if the OP was using a completely opaque material to cover with while doing the test strip.
That's the only reason I can think of why the exposure from the test strip wouldn't translate.
I guess to find out whether it's opaque or not could be found out by simply covering the entire print area with the material and shine the enlarger light on it. Never uncover the paper, and then develop it to see if any density was accumulated or not.
The same test could be done to see if any stray ambient light hit the paper surface during the making of the test strip.
Just some thoughts.
Originally Posted by pentaxuser
Ok, but when you do the last 5 second exposure is the entire sheet of paper uncovered?
Originally Posted by SloboM
The print you made - the one that is too light - does it look like the 5 second exposure from the test print? Or something totally different?
The answers to these questions may help.
A few other questions: What are you using for the blocker? How thick is it? How big is it? What colour is it on each side? Do you keep it right on top of the paper or do you hold it above the paper?
Further to our discussion, the photo paper is in the easel during exposure. I'm blocking light with white tick textured fine art paper slightly bigger than 8x10. 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. Today I'm planing to do new test strip and based on the outcome make another print of the same negative. The funny thing is on the test strip I can clearly see difference in all 6 exposure segments. Unfortunately I don't have scanner to upload test strip.
It makes sense to me you can see the difference in all 6 exposure segments. The method is fine as I said before. We just need to trouble-shoot how you are doing it.
Now that you say you are using art paper for your blocker, I don't know, I think Thomas may be on to something. It could be some light is getting through. Try using two layers and see if that helps. I'd also suggest making them substantially larger than the sheet of photo paper to make sure you don't accidentially end up uncovering part of the paper without realizing it while making the test strip. It also lessens the possibility of stray light getting under there.
Usually for a blocker (also used for burning and dodging), people tend to prefer heavier stock, like 4-ply mounting board in thickness. Illustration board, that sort of thing works well. It should have a flat/matte finish on both sides. It is also helpful to have the side facing the photo paper be a dark colour or black. Most art stores sell this sort of thing with white on one side and a dark colour or black on the other side. That is ideal. The white side faces upward so you can see what you are doing, while the black side faces down.
OK, so you 'think' that the blocking paper doesn't leak light, but we don't actually KNOW for sure.
Originally Posted by SloboM
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.
I very often have a piece of paper, usually my first print that I have placed under the light while still in 'focus' mode. Since it's already trashed, I just expose it to max black. I have a few of these on hand that I use for blocking paper for test strips or making dodging/burning tools.
I think it's the paper you're using, too. I use 300 lb. art paper (with hand-coated emulsions), and it definitely transmits light. Hold your blocker sheet in front of a lamp, to test. My guess is you'll see light coming through. Use heavy cardboard, or (as Thomas suggested) the paper box.
If you'd like to test it on photo paper, cover half the sheet with the photo paper box, and the other half with your blocker sheet. Expose for about 15-20 seconds and develop. If both sides aren't pure white, you have your culprit...
I thought my blocking paper was thick enough to cover the light, but was having somewhat similar (although not as dramatic) problems. I switched to using a magazine. I know there is no way any light is making its way through that magazine.