... I like to cut pastel papers, like Uart, Wallis, Art Spectrum Colorfix, and Canson, to different sizes and bond them to acid free foamboard or gatorboard (which I prefer) using a product called Grafix Double Tack Acid-Free Mounting Film (it forms a permanent bond). I do this because I don't use mats when framing.
Grafix Double Tack Acid-Free Mounting Film is basically double-sided tape in sheet form. Its bond is the strongest I have ever worked with and it holds forever!!
Double Tack is a bit tricky to work with so here is how I do it.
For example, I cut a 16"x20" piece of Uart, I also cut a 16"x20" of foamboard or gatorboard, and also a 16"x20" piece of Double Tack.
1. Peel back about an inch of the backing paper at the top of the 16"x20" piece of double tack and cut it away. So, you are left with the full sheet of double tack, but at the top is the exposed sticky part. Don't ever pull off the backing paper from the full sheet!!!
2. Position it (don't let the 1" sticky part touch the foamboard!) so that the 3 sides of the foamboard and double tack match up, and then press the sticky part of the double tack onto the foamboard.
3. Lift the sheet up and away from the foamboard to expose the backing paper underneath. Slowly pull it to expose the sticky part of the double tack and using a straight edge, SLOWLY use it to smooth the double tack down onto the foamboard so no bubbles form.
The first side of the double tack is now bonded to the foamboard. The next steps will show how to bond the paper to the board.
4. Peel the backing paper back about an inch and cut it away. Position your pastel paper so that 3 sides line up perfectly with the board. Be sure not to let the pastel paper touch the sticky part of the double tack while you're doing this. When everything is lined up, touch the pastel paper to the exposed sticky part of the double tack.
5. At the other end, away from where the 1" was exposed, peel the rest of the backing paper away from the sticky part of the double tack, and using a straight edge, slowly press down every couple of inches to bond the paper to the board so no bubbles form.
6. Turn the whole thing over onto a flat surface and gently press all over the back of the board to make sure the whole thing is bonded.
There!! You have a permanently bonded a piece of pastel paper to a piece of foamboard, or gatorboard. Now all you have to do it paint the painting and frame it using spacers, no mats!!
I'll post some photos soon.