Picture Frame Matting Basics


Matting is one of the least understood, and in many cases most overwhelming aspect of picture framing. The reason is simple; with so many color and texture options, as well as the different quality levels, it is a challenge to make sense of it all. This article will cover each of these items so that the reader can frame with confidence.

What is a Mat?

A mat is a colored or textured paperboard cut to the size of the picture frame. It is placed inside of a frame between the glazing and the artwork with a center cut-out in order to show the artwork. A mat is made of a hard core which is covered on each side by colored or textured paper.

A mat serves two main purposes. First, it separates the artwork from the glass, thereby allowing air flow within the picture frame. It therefore eliminates the risk of the artwork sticking to the glass over time. A second function of mats is to compliment the artwork by gently pulling the viewers eye into the artwork. Matting is most commonly available in Sizes of 32” x 40” / 812 X 1016mm, with some colors available in 40” x 60” / 1016 X 1524mm sizes.

3 Preservation Grades

Matting is classified in 3 quality categories based upon how much acidity exists in the mat board fibers. Acidity, as measured by pH value, occurs naturally in wood pulp from which matting is made. Acidy is not the framers friend; over time, it ‘leaks’ onto the artwork, turning it yellow and brittle.

Unfortunately, there is little consistency between manufacturers. Each grade is available through various trade names given by each of the companies. However, most framers classify matting in 3 grades, each one defined by how much acidity they contain. These categories are “untreated core,” “treated core,” and “cotton.”

Grade 1: Untreated Acid Core

This is the most basic type of matting. The surface of the mat board is chemically treated to reduce acidity, but the core remains untreated. This interior core is exposed when the mat is cut, and the acid leaks from the interior, onto the artwork, causing it to yellow. This is the most basic type of matting and it is only good for the temporary framing (1 year).

Grade 2: Treated wood pulp interior

This product is made from wood pulp fiber that has been chemically treated to significantly reduce the acids that can degrade the matboard and artwork over time. These matboards offer a medium level protection and are the best in terms of protection for the amount they cost. This type of mating is suitable for items that are valuable but not irreplaceable, such as fine art prints, limited editions, valuable documents and non-digital photography (which can be reproduced at a click of a button).

Grade 3: Cotton Based

As the name suggests, this product is not made from wood pulp at all. Instead, it is made from cotton, which is naturally almost entirely acid free. While all manufactures claim that cotton is “naturally acid free”, this is not entirely true. Depending on the crop and growing climate and species, cotton has a PH value that ranges from 6.2 to 6.7 and is therefore slightly acidic. (7.00 would be purely acid free). Having said that, it is the only matting board that is guaranteed to be safe next to any artwork, and comes with a lifetime warranty. The downside to cotton matboard is that it is expensive and can cost twice as much as wood-pulp based product.

What is a Ply?

Another important element of matting is how many plys it contains, though this term can be misleading. In years past, matboard was made of a top, 2 core layers, and a backing; or 4 parts, hence the word 4 plys. Today, most matboard is made with just 3 layers, notably a top, a single core and backing. However, the word 4 plys has not gone away.

For practical purposes, a ply is simply a measure of thickness commonly used in the picture framing industry. Most mats come in 4 plys, or .052” / 1.3mm and are suitable for most picture frame projects. About 30% of mats are offered in thicker 6 plys and even few are available in 8 plys. Thicker plys can be used when rigidity is desired or to create more depth of the artwork.

Colors, Textures and Specialty Mats

More than ever before manufacturers offer a wider selection. Today you have access to an incredible palate of solid colour combination to provide you with every tint, tone and shade you need. The Specialty mats range from distinctive surfaces such as smooth and antique style metals, the look of slate to add dimension and personality, to earthstones to give a granite look, to Raw/Tatami silks, linens, Rice Paper, Suedes to name a few.

Todays technology combines outstanding choices and quality where imagination/creativity becomes reality. Dare to try and you will be positively surprised of the results.