Caution: this may be long.

I've been working with Yupo for a couple of years now - mixed media and a lot of alcohol inks. I always use a finishing UV-resistant gloss spray before matting and framing pieces on Yupo and until now have never had a problem.

I have 9 pieces on 74lb. Yupo that I need to frame (quickly). These pieces are different from successfully-framed pieces in the past in that there are somewhat larger areas on each where there's nothing but exposed paper (and the UV sealer on top)...which I will now refer to as white areas.

I framed one piece successfully but when I got to the next one, some dark grey splotches appeared in the white area - which happens because the Yupo paper is touching the glass.

I tried a double mat, but this didn't put enough distance in to help, because the Yupo paper is bowing slightly.

I visited a professional framer who added spacers between the glass and mat. He did one piece for me, and it looked great. The Yupo was not touching the glass. I purchased enough of the spacers from him to take home and complete framing the rest of the pieces.

By the time I got home, a small grey splotch had appeared again in the white area, so even with spacers and a mat, the Yupo is touching the glass in the frame.

I'm on a deadline (isn't that always the case) and brainstorming to see what else I can try. I don't think I can fit both spacers AND thick double matting in the frames, but that's the first thing I'm going to try.

The other thing I'm wondering about is perhaps mounting the Yupo to something more rigid before matting...a 144lb. sheet of Yupo? Some sort of board? And if I mount, what should I use to adhere to the support - maybe a photo mounting spray? (I will of course test with blank or scrap pieces of painted Yupo so I don't ruin my artwork.)

If I were to try mounting, do you have any suggestions? I plan on experimenting but thought I would reach out in case you can provide any advice.

My first solo art exhibition is 10 days away, so I have to figure something out as soon as possible.

Thank you! :)

Update: going to the framer tomorrow to try dry mounting to foamcore (with a piece that won't matter, should we ruin it!)

I normally do not recommend dry mounting any valuable art work, photograph, or document. The process is irreversible. That is not to say that YUPO cannot be dry mounted. It can be with good results, at your discretion. In your case, there is an additional problem in that your artwork is already complete. (Step 1: mount the paper on board. Step 2: paint on it. Step 3: seal it.)

You might try 3M's Scotch Positionable Mounting Adhesive, a special synthetic adhesive that allows material to be positioned and repositioned for accurate alignment. It will form a high strength permanent bond when passed through the PMA applicator. The adhesive is long-aging, and will not discolor or dry out. If your painting is too large for PMA, you might use an acrylic gel medium.

Several suggestions and observations: First, I used spacers with similar results as you had. I changed to the 144# Yupo which helped.
Next I tried mounting Yupo to adhesive coated foamcore and then used a low temperature pressure (PMA?) Within several days the foamcore had bowed so use thick foamcore. A week later was able to peel the Yupo off the foamcore without injury to the Yupo.
Then I tried spraying the foamcore with adhesive before applying the Yupo and DID NOT lay weight on it as it dried. Disaster! the Yupo rippled, the foamcore surface rippled. I took it to my framer and we used the (PMA?) machine at a low temp and everything flattened out.
Next I sprayed adhesive on the foam core lightly applied the Yupo and put heavy weight on it for several hours. It seems to be holding okay. I am concerned that it won't hold over a long period of time.
I have also tried not putting any glass over the Yupo. I sprayed it with many layers of UV protective non yellowing Krylon. Seems to be protected and gets rid of the reflective glass.
This summer I have noticed that if I lay the Yupo out in the sun after spraying it it has a tendency to bow slightly which is a great concern. Would love to heard more from others about this wonderful, challenging product.
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