Conservation

GLAZING MATERIALS

Glazing materials should be separated from the artwork. Glass is prone to condensation. Moisture builds up inside the frame where there is no ventilation and can contribute to the deterioration of the artwork. Acrylic generates a great deal of static electricity and can cause the artwork to transfer to the glazing material itself. (This is especially true of charcoals and pastels.)

The first technique to separate the glazing from the artwork is to use a window mat. The window mat should be thick enough to create a separation between the glazing material and the paper art. Ply is the term used to describe the thickness of matboards. Standard matboards range between .050 - .060 inches in thickness. 4 ply museum board is approximately .060 inches in thickness. Both can be used for mats or backing boards. Thicknesses less than the above are generally used for backing boards or barrier papers. Double mats as well as 6 and 8 ply boards are available when additional depth is needed.

The second technique is to use spacers. Spacers are the material used to separate the glazing material from the artwork when mats are not used.

To understand glazing products it is necessary to understand the effect of light on artwork.

This chart illustrates the different light wavelengths. The unit of measure of light wavelength is called a nanometer.

The most damaging light is the ultraviolet which is in the 200 to 400 range. This light is powerful enough to induce photo chemical damage to organic material resulting in: loss of color, yellowing, bleaching, darkening and embrittlement.

Visible light is between the 400 - 700 range. (Above 700 is infrared light which is heat.) Within the visible spectrum of light the range between 400 - 500 which are the violets and blues also are damaging to artwork. Although light cannot be filtered out entirely without eliminating these colors there are products on the market that filter out ultraviolet light. The following gives statistics on how effective UV filters are:

Although we do not have comparable statistics on acrylic, all the data we have reviewed indicate that regular and UV filtered acrylic would be at least as effective as regular and UV filtered glass.

When should I use glass and when should I use acrylic?

Glass is the most commonly used material for protecting artwork on paper. The advantage of glass is it is less expensive, easy to clean, and does not easily scratch. The major advantage of acrylic is that it is virtually unbreakable. We recommend using acrylic when artwork is being shipped. When frames are over 32x40, you should consider acrylic because it is 1/2 the weight of glass.

Return To Top

MATTING MATERIALS

What is the difference between the different kinds of matboard?

The prime criteria in selecting matboard is that it should be an acid-free material. PH measurement is the rating of the chemical activity of the acid present in a substance. The PH scale is numbered from 0 - 14, zero has the greatest concentration of acidity and 14 has the greatest concentration of alkalinity.

A "neutral PH" of 7 is desirable in paper because even a slightly acidic condition may have deteriorating effects.

To understand the quality differences between boards it is necessary to understand what they consist of and how they are manufactured.

Regular acid-free matboard - Good
These boards are made up of wood pulp that has been treated.Treatment is necessary because the wood pulp used to make these boards is highly acidic, a result of the chemicals used in the manufacturing process. Acidity in matboards is an important factor. When an acid-free work of art is framed with acidic matting material, the acidity actually migrates into the artwork. These boards are made up of three components. The backing paper and core are made from wood pulp and buffered with calcium carbonate to neutralize the acidity. The facing paper is not buffered. These are the least expensive boards and come in the widest variety of colors. They should be used when color and price are more important than conservation.

Colored rag boards - Better
These boards are also made up of three components. The backing paper and core are made of 100% rag boards and/or alpha pulp (which is wood pulp that has had the acid removed during the manufacturing process).The facing paper is made from alpha pulp. They are buffered with calcium carbonate for added protection. The colors are all fade resistant. For those of you who are more concerned about conservation yet need more colors than are available in the museum boards, these are a good choice.

100% rag boards (museum boards) - Best
These are solid boards made up of cotton and linen rags which are made into a pulp.. They are completely acid-free. These are also buffered with calcium carbonate. This helps to reduce the acidity that can migrate from other components of the artwork package.All colors are fade resistant, although color selection is limited. It is considered the best protection you can put on your artwork and are the only boards used by museums and fine art galleries.

Return To Top

HINGING MATERIALS

There are many different hinging materials i.e. Japanese paper & paste, pressure sensitive tapes, as well as materials made especially for photographs.

Japanese paper & starch paste
The time proven method used by museums is to make strips of long-fibered Japanese paper and use a wheat or rice starch paste. Paper by weight is approximately 6% water, and therefore absorbs & releases moisture. A paper hinge is used because it will expand and contract like the artwork. Starch paste is used because it has great adhering power, won't discolor, and is water reversible. A hinge made with starch paste will be as easy to remove years from now as it is 10 minutes after it is applied.

Archival Pressure sensitive tapes
Although not museum quality, archival tapes have become very popular because they are acid-free and easy to apply. They typically do not discolor or soak into the paper. The disadvantage of these tapes is removability. For a short period of time they can be removed with water (except on photographs). There can be difficulties removing them after a longer period of time and solvents may have to be used. We recommend using them when the ease of application is more important than strict conservation.

Mounting Corners for Photographs
This is the best method for mounting photographs. No adhesive touches the artwork. They are easy to apply - just peel and stick. They are also used on matted pieces when the artwork is very heavy, such as watercolors.

Return To Top

FILLER BOARDS/DUST COVERS - CONSERVATION CONCERNS

Filler boards should be archivally safe. This is the material used behind the backing board or artwork. The filler board acts as a barrier against acid migration and dust, fills space, and adds rigidity to the finished frame package. Various boards can be used: 100% rag boards, acid-free foam boards, or archival corrugated boards. We do not recommend standard corrugated boards because of their acidity.

Dust covers keep dust and insects out and slow the rate of temperature and humidity changes. The traditional method is to cover the back of the frame with kraft paper. The problem with this is that not only is the paper usually very acidic but it inevitably tears and therefore defeats the purpose. We recommend using dust cover tapes. They are available in regular and acid-free versions.