Glass or Plastic Glazing?

 

Framing: Glass or Plastic Glazing?

Q: AIM For Arts required paintings glazed with either Plexiglas or Perspex (whatever that is). What is the best as far as glazing, UV proof etc or regular glass?. Thanks, Gloria

A: When we talk about painting in oils and acrylics “glazing” means to apply a thin transparent layer of color over an underpainting. For the framer, it means to fit a picture frame with glass or glass-like material. The AIM for Arts organizers simply requested the use of a plastic glaze instead of glass. Probably because it does not break as easily as glass and they were concerned about shipping and handling of the artworks.

You can frame a picture using either glass or a plastic product, like “Plexiglass.” Glass and plastic used for framing pictures are like most products, the more you are willing to pay, the better the quality will be. The more expensive glass, like “Conservation Glass” is also designed to block Ultraviolet rays. Ultraviolet light rays cause fading and darkening of colors and can produce chemical changes that can make artwork brittle and structurally weaker. The major sources of ultraviolet light are fluorescent lights and direct sunlight. Non-glare glass is glass that has been etched to diffuse the reflection. The greater the space between the non-glare glass and the artwork, the fuzzier the image will become. The distance of a single matt is acceptable for most people.

There are different types of plastic sheeting that are used for framing but the most common is clear acrylic (polymethyl methacrylate). “Plexiglass” is the trademark of Rohm & Hass for clear acrylic sheeting. “Perspex” is another word used to refer to plastic sheeting. Not very many people use acrylic to glaze pictures and some framers don’t even stock it. Acrylic has some advantages and disadvantages over glass: it is clearer and transmits more light than glass (90% instead of about 83% for glass); it is lighter and less breakable and this is important for larger works, and; it is easy to score and cut to size. The disadvantages of plastic glazing are that it is very easily scratched and it cannot be used for pastels, charcoal, or chalk artworks due to the static charge that it develops. This can cause a significant amount of the material to be lifted off of the artwork and it will stick to the acrylic sheeting. Acrylic can also be a fire hazard. When plastics like this are heated or burned without sufficient oxygen (which is the case in most house fires), they give off large quantities of toxic vapors. Acrylic sheeting that filters ultraviolet light is also very expensive.

A good framer will be able to provide more specific information regarding the various types of glass and plastic glazing available, and their prices.

Thanks for the question