Why is this Happening?

[ASA1000]

Only One Edge of SOME prints dry like the edge shown in the image. It's always the short side (its sticking out so you can see it!)
There is no pattern as to which short side of the paper wrinkles. This has happened with two different boxes of paper. Maybe 1 out of 6 or 8 sheets will do this.

My Process is basic: Illford fiber base. Wash, double fix, hypo clear, wash 30 min. Then blot dry, dry face down on a screen and flatten in the press @ 165 for 4 minutes, then between two sheets of glass to cool.
I'm in Colorado, in a dry basement, with about 40% humidity today. There is some air flow from my ventilation fan. Everything is between 68 and 70 degrees.
I have also tried a squeegee, it makes no difference. I have tried smoothing the edges with my fingers while the paper is wet, also no difference, although you can't see the wrinkles until the paper COOLS. If I air dry, it takes some hours to begin to wrinkle
I have tried less time in the press and more... nada!

Any ideas? I'm about out.
thx!

[Ulophot]

Normally, this happens when humidity is too low, and it happens in the dry mount press heat when mounting. Why you are getting apparently these random results stumps me, too, from the info given. In my experience, lightly dampening the back of the print along the edge before pressing it can at least ameliorate the problem.

[Tin Can]

Agree

But I go right to mounting and never expect FB to stay FLAT

[nolindan]

Likely due to paper manufacturing. The wrinkle would be on an edge in the mill direction and towards the outside of the paper roll.

I've just always expected things like this. I've never had it survive trimming and dry mounting.

[MartinP]

It should be reduced or eliminated by trimming a millimeter off the 'wavey' side. It was explained to me as being some sort of effect from stresses at the edge of the paper-roll when it was manufactured, hence before it got to the photographic coater. Sometimes a group of sheets of finished photo-paper will be from that part of the paper roll, and sometimes not.

[ASA1000]

Likely due to paper manufacturing. The wrinkle would be on an edge in the mill direction and towards the outside of the paper roll.

I've just always expected things like this. I've never had it survive trimming and dry mounting.

Do you know which way the paper is cut? Is it an 8 inch roll cut at the 10 inch side or a 10 inch roll cit on the 8 inch side? I've looked at the edges with a high power glass and I see no marked differences.
thx !

[ASA1000]

Agree

But I go right to mounting and never expect FB to stay FLAT

Trim and mount would be easy, but I have to make a lot of prints for the museum of N.M. and they need to lie flat, so I'm trying to figure this out. I can't imagine that EVERYONE has this problem.
Thx!

[ASA1000]

It should be reduced or eliminated by trimming a millimeter off the 'wavey' side. It was explained to me as being some sort of effect from stresses at the edge of the paper-roll when it was manufactured, hence before it got to the photographic coater. Sometimes a group of sheets of finished photo-paper will be from that part of the paper roll, and sometimes not.

That seems logical, but I can't make that work since, it's not always the same side when it comes right out of the box. I looked at squeezing the paper and stopped doing that because I thought it was pulling water one way into the edge and one way off it........ so I went to blotting.... same problem.
Thx!

[ASA1000]

Zoom in and look at the edge of the platen and how it's higher on the right side than the left. Perhaps .......?
It will be Monday before I know

[Mark Sampson]

Hmm. I started seeing this when I moved to ultra-dry Tucson. At first I thought it was my new (old) dry-mount press. Then I was given another press, and the issue (mostly) went away. So I think it's mostly humidity and then a matter of mounting technique. But I'm not certain of that.
One change I've made has been to dry my prints between two screens, instead of on top of one, in an attempt to reduce curling. That seems to help.

I never thought of it as a function of what part of the master roll the paper sheets came from. Those are very wide... It seems unlikely, based on the many hundreds of prints that I've flattened, in many different presses, over the decades. And the many brands and types of papers that I've used. But who knows?