Acid free vs. "regular" matting for framed art.

“Because acid free mat board is only temporarily acid free, it is not considered archival and should not be used for conservation purposes. If you want to mat original, one-of-a-kind works of art, limited edition prints, or any type of valuable paper memorabilia, you should not use an acid free mat board. Instead, you should use an archival, museum quality rag board that is naturally acid free. Mat board comes into direct contact with the artwork, so if you want to preserve and protect your artwork, you should choose a mat board such as Crescent Ragmat or Bainbridge Alpharag.” Source

For long term conservation, museum quality framing and matting is required. You can have any professional do it, for a fee.

I’m wondering why no one is answering the question:
“The mat really only contacts the artwork along a very narrow strip around the borders. Is it possible for the acid in the mat material to leach further into the artwork or would any potential aging be limited only to the points of direct contact?”

I would like to know that too :)

Does the acid actually harm the artwork in any way? Or does it depend on the type of artwork and paper/canvas?

@PluckyDog “The difference is important for the long term protection of the piece because acidic mats can cause what is called mat burn, brown marks that creep in from the outside onto the displayed piece itself. While mat burn is sometimes reversible through cleaning the piece, cleaning may not be feasible if the piece was executed in water-soluble inks or paints, such as watercolor. Thus, it is important to know if the mats used are acid-free if the piece is to be preserved for a long time.” From Wikipedia

Ahh, thank you kindly :)

Acid-free all the way. It really does matter after time. In my experience it can leach, but not more than an inch or so. I’d like to see his stuff!