Matting

 
Rag mat samples
 Let me state this from the start; when in doubt of the archival properties of a matboard, always use 100% cotton rag museum board for preservation purposes. It is fully archival, naturally pH balanced & acid free, and contains no lignins. Although more expensive, cotton rag museum board is the standard for archival matting & has stood the test of time. Once limited in their color spectrum, rag mats are available these days in a wide variety of of shades, ranging from whites, off-whites, light grays, grays, to various different cream colors, as you can see in the photo to the right with just some of the samples available.

   The manufacture of mat boards has come a long way in recent years in becoming more aware of archival needs. Almost gone are the days of straight wood pulp mats, with their large amounts of lignins that broke down, creating & out-gassing acids that discolored not only the mats, but the artworks they held. Many picture framers in the past have used cotton rag barrier papers to prevent these poor quality mats from touching the artwork, and although this helped somewhat, much damages could still be done by the out-gassed acids. So.... take a look at your framed artwork. Is the core, (bevel cut), of the mat white?, or is it discolored? If it is discolored, or if there is discoloration on the artwork near the bevel cut, I would suggest replacing the mat as soon as possible.

   Today, mat board manufacturers are still using wood pulp to keep the price point down, but are using many techniques to make the mats less acidic & more artwork friendly. In the long run this is good for framing & artwork, but the techniques can range from not so hot.... to really good, and everywhere in between. Some mat board makers simply add just enough inexpensive buffers/alkaline content to make the mat core pH balanced at the point of sale as to call it "acid free", yet still have a colored plain wood pulp paper on top. Not so hot!, in cases like this, "acid free" does not in any way mean archival. The wood pulp lignins can still break down, giving off acids that counteract and overcome the buffers, causing the pH to go acidic & affect the artwork. On the other end of the spectrum, some manufacturers use 100% Virgin Alpha Cellulose wood fiber with the lignins extracted, for the core & the top paper. They are buffered, often to the slight alkaline side of pH balanced, & can have additives such as zeolite, both which help later absorb any acids or impurities in the framed artwork package. Some pretty good matboard it seems, as it has been tested in aging acceleration labs under intense lighting, temperature, and humidity conditions, and has many endorsements from well know organizations as being "museum quality". I do often use this type of matboard when a customer must have some color in their framing or wants to keep the pricing down, but always mention the fact that it may not be fully archival. And, just as a side note; some organic items like parchment, vellum, & albumen photos can react to a high alkaline environment.

   At a recent picture framing convention, I was talking to a salesmen from a nationally known matboard manufacturer about all his different matboards & their archival qualities, and in the end he said, "If you want to go 100% archival, then you should use our 100% cotton rag museum board." Now, he was either being a good salesman in pushing their most expensive product, or as my husband asked as we were walking away, "What exactly does that say for their other matboards?" Hmmmm.

   When matting a piece of artwork, I usually create a "mat package" by hinging the matboard to a museum board backing to which the artwork is mounted. Please see the Mounting section for more on the many ways to do this.