Using Convex Glass for Antique Picture Frames

Antique picture frames are an interesting way to walk down memory lane. A distinctive feature of these frames is the use of convex glass. Also called domed glass or bubble glass, the convex glass is fitted into the frame and usually displays treasured family portraits. Nowadays, extra deep convex glass is also used to mount 3-dimensional objects (such as wedding bouquets and other personal mementos) into a frame. Convex lenses can also be glazed with silver film to make unique convex mirrors.

Convex glass is produced by placing a sheet of flat glass on a frame mold. The glass is then heated to allow it to be bent and curved without it breaking. The deeper the bend, the longer the heat is applied. Convex glass is usually at ¾” to 1 inch deep at its highest point. However, convex glass with extra depth can also be custom-bent according to the client’s preference.

The glass is designed to fit oval picture frames, as well as circular, square, rectangle or octagon-shaped picture frames. Victorian Frame Company provides replacement convex glass for the antique picture frame you already have. You can also order a combination of picture frame with fitted convex glass.

Convex Glass Solutions

Convex glass is bent so as to provide a depth and not touch the photo except on its edges, where the picture and glass is attached to the frame. If you desire to put a replacement bubble glass on an antique picture frame you already have, be sure to measure the dimensions of the frame carefully. Remember that the convex glass is not measured on the curve, rather on the length and the width across the glass.

You can mount the photo you want displayed either laid flat on the mounting board at the back or laid against the glass. When leaving the photo flat, you can simply attach the photo to the backing of the frame. If you plan to use glue, check that it is acid-free photo glue to prevent any acid damage to the photo. Laying the photo flat prevents the picture from sticking to the glass due to any moisture present, which was a common problem during the turn of the century, when bubble glass were first used. Laying it flat also prevents any cleaning fluids from making its way to the photo and causing it to stick to the glass.

Another way to display pictures using a convex glass frame is to create a bubble form that mimics the shape and curvature of the lens. The picture is fitted into the lens. You can use acid-free glue so that the photo adheres to the bubble form. When using this method to mount your photo, be sure to carefully measure the convex glass and frame you need, since the curvature will mean a smaller border size for the photo. To avoid damaging a particularly valuable photo, you can get a photocopy of your photo and use this duplicate to experiment and see what convex glass size you require.

A word of caution about convex lenses

It is important to remember that most convex glasses in the market do not provide UV protection. The process of applying heat in bending glass destroys UV protective properties in the glazing. Light, not just the rays of the sun, but even artificial light can cause damage and discoloration over time. If you plan to display a valuable photo, be sure to keep a digital copy of the picture on hand and keep the picture frame away from direct sunlight.

14th Jul 2014 Eric Morgan

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