Many may ask, What is Glazing?
Glazing is the covering the artwork with a form of glass or acrylic to protect the artwork. The ideal glazing material would transmit, without distorting, all of the light in visible spectrum and would block ultraviolet rays. It would resist impact and carry no static charge; (framing of larger pieces acrylic should be used and not glass.)
The only aging process glass is subject to which may be of interest to customers is that, with time, microscopic surface scratches may slightly reduce light transmissions. Acrylic, like all organic materials, ages but very slowly.
Deflection and Thickness:
Glass is rigid, and in picture frames deflection is barely perceptible and unlikely to pose a risk to framed art. Acrylic sheet is flexible and subject to deflection, which distorts reflections. The major concern of framers is that acrylic glazing may bow in, touching a framed work of art. Secondly, acrylic is subject to high static charge and when framing loose media, such as charcoal, chalk, or pastel, and thin or lightly sized papers will be attracted to static charged acrylic glazing. increasing the distance between acrylic and framed artwork lessens the attraction, but to be effective a separation of several inches may be necessary. Glass would be a better alternative when framing these materials.
Standard picture glass absorbs most of the UV rays and offers little or no protection from fading of the artwork. However, there are several glass sheets that offer up to 97% UV protection; these sheets are coated and have laminated sheets between two sheets of glass. At Fast Frame-Dilworth we recommend Tru Vue Conservation Clear or Museum Glass.
On your next trip to your local frame shop, hopfully you’ll select Dilworth Custom Framing, please consider asking these questions:
1. Is the artwork susceptible to UV damage?
2. Under what lighting conditions is the work to be displayed?
3. Is it likely that the work will be shipped?
4. Is the media loose?
5. How stiff is the paper support?
Source: (PFM February 1996, Glazing page 36-37)