Working with Polaroid Type 5X "negatives"

O.k. So I have noticed that on B/W Polaroid sheet film, I was getting a readable "negative" opposite the print. If I was careful and let it dry, I actually got something that could be scanned into my PC, reversed in PShop and used. The look was old and arty and had some interesting aspects to it.

I did this with 400 and 800 speed films. But recently I tried the same with some 100 speed and I got NOTHING on the opposite side. Just black. Good positive, no "negative".

Anyone know if this is enedmic to the type of film used or maybe something else? I will say that with the 800 and 400 speed I developed at 40-45 seconds due to temp as opposed to 60 seconds for the 100 due to temp.

Polapan 100 and polapan 400 do not give you the "negative" the old type I think designated with the 50 numbers did give you the "negative".

If you were using Polaroid 54 - ISO 100 black and white - this is normal. There is no negative. You are supposed to get a positive print and a sheet of black stuff.

Type 55 P/N yields both a positive and a negative. You clear the negative in sodium sulfite after development. They have different speeds. I rate the positive at 80 and the negative at 40. You have a limited tonal range (Zone 7 is about top end) and no control at all over contrast. Still, some nice images can be made with it.

This is the only film made by Polaroid which yields both a positive and a negative. 4 x 5 is the largest size in which you can get it.