Convex glass works well in an oval frame.Hemera Technologies/PhotoObjects.net/Getty Images
A bubble glass frame contains a convex piece of glass rather than the traditional flat piece. This type of mounting style was popular at the turn of the 20th century and was often used to display family portraits on the wall. Whether you have a family heirloom or a bubble frame from an antique store, mounting pictures in the glass is similar to using a regular picture frame.
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Bubble glass frames aren't easy to find, but are available at some antique stores or specially ordered on the Internet. The glass rounds outside the frame's borders and the photograph is mounted inside the glass so it mimics the bubble shape. Placing the picture inside the glass varies slightly from using a regular frame. The shape of the glass was designed to protect the photo's quality in humid environments where houses didn't typically have a cooling system.
How to Mount
Mounting photos in convex glass can be done in two ways. Leaving the photo flat works well because it prevents the picture from touching the glass, which keeps cleaning fluids from damaging it and prevents the photograph ink from sticking to the glass. This method involves adhering the photo to the frame's backing, typically made out of cardboard. Use acid-free photo glue and center it on the cardboard. Insert the cardboard into the frame and secure it with the frame's brackets. Authentic convex photo frames often placed the photo against the glass, which required creating a bubble form for the picture. According to Photos Made Perfect, a photo restoration company, this involves mounting the picture on a convex board that is the same size as the frame. The board and photograph are mounted inside an oval frame and closed in back with the frame's hardware.
When mounting a photograph to a convex board, apply the glue to the board rather than the photo, which makes it easier to get the photo in the right place before pressing it into the adhesive. If you are new to convex glass mounting techniques, practice on photocopies or magazine photos to prevent damaging a valuable family photo. If you are concerned about the durability of a photo or want to re-frame a photo already in convex glass, consider consulting a professional with experience restoring antique photographs and bubble glass frames.
Choosing Bubble Frames
Bubble frames are typically round or oval in shape because the convex shape makes it easier to match. If you are mounting a photo that was not inside a bubble glass frame, consider the size before choosing a frame. The size will not be the same as a flat frame because rounding the photo will create a smaller border size. Trace the photo on a piece of paper so that you can test various bubble glass frames without harming the photograph. This allows you to find the perfect fit, which will make the photo look authentic when it hangs on the wall. For a photo already framed in a bubble glass frame, measure the circumference of the inside of the frame and purchase one that has the same size opening.