This is the second half of a two-part article on picture frame glazing. In the last issue of Preview we covered glass materials; in this issue acrylic glazing is discussed.
Acrylic is generally used when size or weight is a concern. The larger the frame, the more risk there is, to art and person, from broken glass. Acrylic is much more impact resistant than glass, and about half the weight. These are important considerations when framing oversize art!
Shadowbox with regular acrylic on left, and antireflective Optium Museum on the right
Acrylic has lower thermal conductivity than glass, so it is much less likely to have condensation issues. This makes it possible for items like textiles to come in direct contact with the glazing, as in pressure mounting techniques. Acrylic can also be solvent-joined and heat-bent to create three-dimensional mounts and display boxes.
Acrylic does have two drawbacks however; it bows, and it scratches. The thicker the sheet, the less it bows, but the more it weighs. Bowing issues and weight considerations need to be taken into account when designing oversize framing systems. The impact resistance of acrylic makes it an attractive option for use in public spaces, but its soft surface mars easily from abrasion and solvents, making it a favourite target for vandals.
Much of the product used by the framing industry is made by Cryo Industries, with the trade name Acrylite. Acrylite products most commonly used in framing are:
- FF-3 plain clear
- P-99 clear etched (to reduce glare by scattering reflected light) and
- OP-3, which has UV filtering built into the sheet (not a coating).
FF-3, P-99 and OP-3 are also available with an abrasion and chemical resistant coating on both sides and are designated by MR (mar resistant).
- Acrylics reflect 8% of light (like glass)
- FF-3 and P-99 filter 66% UV light
- OP-3 products filter 98% UV light but have a slight yellow cast
Tru Vue, a major supplier of frame glazing, markets FF-3 as Premium Clear, P-99 as Reflection Control, and OP-3 P 99 as Conservation Reflection Control. Tru Vue also supplies some unique glazing materials:
- Optium Acrylic FF-3 MR with anti-reflective coating on both sides. The combination of MR and optical coatings increases UV filtration to 93%.
- Optium Museum Acrylic is OP-3 MR with a proprietary anti-reflective coating on both sides. UV filtration is, like other OP-3 products, 98%.
- The anti-reflective coatings on Optium products reduce glare to less than 2%.
MR products are anti-static, making them safe to use with friable media such as unfixed pastels. Optium products are also anti-static. Under certain lighting conditions (natural daylight) Optium Acrylic can show a pink cast, so it should be tested in situ before using.
Uncoated acrylic products must be cleaned with acrylic cleaners or alcohol/water solutions (rubbing alcohol is the most usual). MR products must be cleaned with glass cleaning products, or alcohol/water solutions. Optium products must be cleaned with alcohol/water solutions. The solution should be spritzed onto a clean microfibre cloth, not directly onto the acrylic.
Previously: I can see clearly now or can I?
Next issue: Old and new methods for cleaning paintings