Most framing experts agree that it is best to keep the pastel surface away from the glass.
Framing a print without a mat.
First we attach your art to an acid free foam core lift hidden behind the work but mounted to a supporting white mat.
When matting is eliminated the framing options are to either sandwich the painting against the glass an old french method or to utilize a spacer.
Second we use a spacer to create space between the plexiglass and the surface of your work.
If there is a border around the image that border will be visible unless you cover it with a mat or cut it down and get a smaller frame.
If you just put a print into a frame without a mat or spacers contact with the glass can cause sticking buckling newton rings and a variety of other problems.
Like a mat floating gives the piece some space.
Picture frames destination inc.
The trick is to use spacers to create an air gap between the print and glazing glass or acrylic.