Ripples on 20x16 prints Epson P800

[TonyW]

This morning I printed a few 16x20's on a 17" roll of  Canson Rag Photographique 210 on the Epson SC P800.  These are to be wall hung in frames with a bevel mat board.

Leaving them to dry for a few hours on examination found that all have ripples on the surface.  Attached is a phone capture of the back of the paper which shows the issue most clearly.

I suspect that the Media settings were a little too ambitious for this paper weight although based on Canson recs. for this paper.  Details below in case I have missed something:
Media Settings
Media Type:  Velvet Fine Art Paper (Matte Black Ink)
Print Quality: Quality (Level 4)
Setting Information:
Print Quality:  Superfine - 1440 x 720 dpi
Microweave: On
High speed and Finest Detail checked

Anyway the damage seems to be done and rather than reprint I was thinking about ways that might cure the issue.  I would appreciate advice on this but in the meantime this is what I am considering.  In order of preference:

1.  Sandwich between large sheets with weights for a few days
2.  Lightly dampen the back of the prints and individual sandwich as above
3.  Spray back with Photomount adhesive as a last resort and see how long they last

[Kyle Jackson]

Wow that's some extensive cockling  This is the first time it's done that? If these settings normally give a suitable ink load, I'm wondering if your ambient humidity is much higher recently. Or if it's a defective batch of paper.

[TonyW]

Wow that's some extensive cockling  This is the first time it's done that? If these settings normally give a suitable ink load, I'm wondering if your ambient humidity is much higher recently. Or if it's a defective batch of paper.

This was the first time using roll paper, previously using the same paper in sheet form OK.  Humidity no appreciable change.

I suspect user error rather than defective batch.  Thinking about this again the only other factor is the subject matter which is an abstract with large areas of single saturated colour.

EDIT:  After placing the prints between foamcore boards weighted down with books for a few days the prints have flattened to an acceptable level