For this installment, we are going to talk about a basic element of frame construction called the “allowance”. You may have heard the term in the past in a frame studio. So what is an allowance and what does it do?
Frame construction can be very simple, or very complex depending on what is being framed. An example of simple framing is a stretched canvas being put in a simple perimeter frame. An example of complex framing would be a work on paper with several mats including both paper and fabric mats, decorative fillets, museum mounting, U.V. protective glass or acrylic glazing and a carved and gilded frame.
Both of these frames have something in common: that the materials will change shape with the changes in temperature and humidity. They will expand and contract. If the materials inside the frame fit tightly it will have adverse effects. In the case of the framed work on paper, those changes could warp and or destroy the mats, make the acrylic glazing wavy or, if it was glass - crack, and adversely affect the artwork. In the case of the painting it could stress the stretcher bars and also stress the painting canvas in several different ways.
So, as framers, we build an “allowance” into the construction of each piece from side to side, usually 1/16” space between the edges of the mats and glazing - and the inside side surface of the frame. If everything is centered properly, there will be a 1/16” gap all around the inside (1/8” total) that will allow for the inevitable expansion and contraction of the materials inside of the frame. There could be more or less depending on the materials being used, the size of the frame and the type of art being framed.
We also have to be careful not to sandwich all of the materials in too tightly from front to back as this will also restrict free movement of the materials from side to side by binding them, and front to back as well.
An allowance is a critical component of all custom framing and now you know why. Stay tuned for more usable information about custom frame design and construction from source here at Santa Barbara Art Frame Company.
Questions and comments welcome.