Material & Techniques

Artworks made on paper, fabric or similar supports require framing for protection from the atmosphere and handling. This task is best left to professionals; however, any artist who decides to do this on their own should follow some established rules. The cost of using the best methods and materials may outweigh the value of an artwork. The artist should use their judgement on the extent of protection needed for the artwork by considering the most likely causes of deterioration in the circumstances.

Unless necessary, artworks should not be mounted on a board. Where there is mounting, it must be done on a conservation board using a glue or adhesive that is pH neutral, of vegetable origin, and reversible. The choice between an organic water-based or solvent-based glue or adhesive is largely dependent on which material is less likely to affect the type of artwork (e.g., watercolours, etching, acrylics) during application and removal, should the need arise.

Artworks should never come into contact with the glazing, which is usually made of glass or acrylic. There are two reasons for this rule. First, glass, in particular, tends to condense moisture and cause mould and mildew to grow on the artwork. Second, acrylic paintings can adhere to glazing over time and cause irreparable damage when removed. A matboard or spacer can be used to separate the artwork from the glazing. Where a matboard is used, small to medium artworks must be secured with tape only in two places to accommodate the natural expansion and contraction caused by changes in temperature; if it is secured in more than two places, ripples may occur. Larger artworks, however, need to be secured in more than two places to hold them in place. The tape should be pH neutral and non-yellowing, An archival tape is good for this purpose. Never use scotch, masking, drafting, and packing tapes in framing.

Charcoal and pastel artworks should only be glazed with glass because acrylic sheets tend to develop static electrical charges and cause lifting. Using a fixative on the artwork may provide some protection against this type of lifting.

There should always be a 1/4 inch margin between the edge of the artwork and the wood frame. Wood generally becomes acidic with age. Contact with a wood frame will cause acid migration to the artwork that will affect the composition of the paper and cause it to break down or brown. The acid migration might also cause colour changes to the artwork.

The backing board should be made of 100% rag or be lignin-free and buffered with alkaline to counter the absorption of acid from the atmosphere. Museum and conservation boards are suitable for use as backings. Boards made of wood (ground or pulp), chipboards, and cardboard are not suitable for use as backings. These boards tend to be acidic and have iron and copper content that will oxidise and stain the artwork.

Lightfastness is the retention of a pigment’s chromatic properties over many years. A lightfast pigment is able to resist change when exposed to light and the atmosphere. This is important in paintings. Information about lightfastness helps the manufacturers and users to determine which pigment is suitable for use in artists’ materials.

Lightfastness can be determined in one of two ways: first, by examining the pigments used in past paintings that have not shown any visible change for seventy-five years; second, by an accelerated ageing test. A pigment that has shown. no change visible for seventy-five years is likely to remain lightfast for one hundred years or more.

The accelerated ageing test - which induces colour changes that may occur following long term indoor illumination - is theoretical and speculative. The manufacturers of pigments and paints have not adopted a standardised test for all because there are so many variables in the assessment of lightfastness.

The two common testing procedures are the 'ASTM Standard Test Methods for Lightfastness of Colorants Used in Artists’ Materials' and the 'Blue Wool Standard Lightfastness Test'. The ASTM abbreviation stands for the American Society for Testing and Materials. The Blue Wool test was originally developed for the textile industry and was later adopted by other industries that use colourant in their products.

The ASTM test requires tinted pigment samples to be exposed to either sunlight, fluorescent light, or xenon arc light filtered through a glass in a specified way for a specified time. Light from the Xenon arc lamp is the nearest artificial light equivalent to sunlight. The lightfastness of the pigment is determined based on the colour difference between samples before and after exposure to light as measured with a spectrophotometer. The pigment sample is then assigned one of the following ratings.

I—Excellent Lightfastness (very slight to no colour change after the equivalent of one hundred years of indoor museum exposure)

II—Very Good Lightfastness (Less permanent than Category I, but satisfactory for most indoor painting)

III—Not Sufficiently Lightfast to be used in artists’ paints (Borderline. Use with caution)

IV—Poor Lightfastness

V—Very Poor Lightfastness

Manufacturers who adopt the ASTM guidelines for their testing procedures will specify the rating on the individual paint tube labels. An artist who wishes for their paintings to withstand the test of time should only use materials containing pigments with ASTM ratings I and II.

The Blue Wool test exposes pigment samples alongside eight samples of wool dyed with different blue pigments to a Xenon arc lamp. The light from the lamp causes accelerated changes in the blue pigment samples which can be matched with a number of years of indoor illumination under normal conditions. The test simply compares which dyed blue pigment (numbered 1 to 8) fades at the same time as the pigment sample and assigned one of the following ratings.

1—Very poor lightfastness (fugitive, less than 2 years)

2,3—Poor lightfastness (fugitive, 2–15 years)

4,5—Fair lightfastness (impermanent, 15–50 years)

6—Very good lightfastness (50–100 years)

7,8 —Excellent lightfastness (over 100 years)

Some manufacturers have their own testing procedures or will adopt the ASTM or Blue Wool procedures with modification to determine the lightfastness of pigments. The results of the testing are translated into proprietary information about “permanence” on the label. That information may sometimes be coupled with the ASTM rating. The manufacturer's permanence information usually uses letters and symbols such as AA, A, B, C or asterisk ****, ***, **, * with nomenclature such as 'Extremely Permanent', 'Permanent/Durable', 'Moderately Durable' or 'Fugitive' to indicate the durability of the pigment. There is usually no information about the length of time attached to each category because the manufacturers are concerned that it would be construed as a warranty. Under these circumstances, it's best that artists do not purchase materials where the pigments are rated to be less than 'Permanent/Durable'.

In the art world, the term archival means something used to protect artworks kept in a controlled indoor environment from deterioration. The usual example of a controlled indoor environment is a museum. The common causes of deterioration are light, temperature, moisture, air pollutants, airborne particles, insects, and vibration. Strictly speaking, conservationists expect properly cared for artworks to last for a minimum of seventy-five years.

Archival materials should not age rapidly and be able to protect the artwork from ultraviolet and infrared light, air pollutants, insects, acid migration, mould and mildew, stains from oxidation of metals (e.g., iron and copper) and changes in temperature and moisture levels.

PH neutrality (commonly referred to as acid-free) is an indispensable criterion for archival materials. Otherwise, acid compounds in the material or absorbed from external sources will migrate to the artwork during natural ageing and cause damage. For that reason, materials like boards and paper (which come into contact with the artwork during storage) are not only required to be acid-free when they leave the factory but also be buffered with alkaline reserves to counter acid compounds absorbed from the atmosphere over time.

These are some of the common products used in the storage and preservation of artworks: shelves, wire mesh screens, framing materials, cloth, panels, films, fabrics, foam core, mat boards, cardboards, tube rolls, paper, tissue, polyethene sheets, polypropylene sheets, polystyrene, bubble wrap, boxes, folders, zip lock bags, cards, binders, velcro dots, seals, tapes, labels, photo corner, adhesives, waxes, gels, putties, pads, weights, hanging bars, straps, tie-downs, buckles, metal rods, staples, hooks, and insect control products.