Although this is the most commonly used glass, it offers little protection from damaging
light rays. It should only recommended for items of little or no value as they will
fade over a comparatively short time.
The anti reflective coating reduces reflection typically to less than 1%. It can
make the glazing seem invisible and is particularly recommended for darker items.
UV filtering glass
The coating on this glass will filter 98% of UV rays. UV is in all natural light
and will affect paper colour and water colours particularly; especially if any sunlight
washes the picture.
In the picture here you can see how the paper has changed from cream to ochre and
the depth of colour has leached from the picture giving an almost monochromatic effect,
leaving only blues and browns.
This a combination of UV filtering and anti reflective glass. It is very good but
Perspex (actually a trade name) or acrylic glass has improved enormously in recent
years. The Rijksmueum in Amsterdam which re-opened in 2012, is glazed completely
in top quality acrylic glass which has all the properties of museum glass as also
being shatter and scratch resistant and lighter in weight. These latter qualities
have a real function for pictures to be hung in children’s bedrooms or public places
where safety is a concern.
Budgeting for glazing
When considering the cost of the glass; rather than comparing the price per square
metre, compare the actual cost with the benefit of the superior product. Here are
the different types of glass in cost order.
Standard acrylic is similar in cost to float glass with superior acrylic comparable
in price to museum glass.