null Skip to main content

Cathedral Convex Glass

Cathedral Convex glass is a common shape of convex glass and is sometimes referred to as a "single boiler" referring to the 1 rounded end bulging or "boiling out" out from the two straight edges. We have been bending and fitting antique replica cathedral convex glass since the early 1970s, Cathedral Convex Glass is available in these sizes:

10x16          11 1/2 x 19 1/2

Additional Custom Sizes Available up to 20x24   

Click here to order Cathedral Convex Glass

Measuring Cathedral Convex Glass

Cathedral Convex bubble glass is measured just like cathedral flat glass, measuring length and width directly across the glass (not around the bend of the glass). Cathedral convex glass generally has a depth of between 3/4" to 1" although deeper bends are possible.  Many people are concerned that the odd cathedral sizes are no longer available or will require custom bending fees. 

We also custom bend any size of cathedral convex bubble glass up to 20" x 24". Each custom bend requires a paper tracing of the size required. Please mail us this tracing with your name, and phone number. The line you draw will be the line the glass is cut to. Please allow 3-4 weeks delivery after we receive the tracing to produce your custom size convex glass.


Many picture frames produced in America by some the largest picture frame factories in the late 1800's up to about 1940 were unusual shapes including the cathedral shape of picture frame. A large percentage of these frames were used to frame family portraits with convex glass. Today many attics and basements are home to these family heirlooms framed in antique frames and often broken convex bubble glass.

OVALCREST has been bending convex glass replacements for these images since the early 1970’s and today we continue to manufacture convex glass along with a unique collection of antique replica frames. 

Uses of Cathedral Convex Glass

Most cathedral convex glass is used to cover antique portraits in which the photographs themselves were also convex. We produce convex glass to fit our own antique replica frames, and also can supply an cathedral convex glass replacement to fit actual antique frames. We also regularly produce convex glass replacements to replace broken pieces in clocks, gauges and other instruments.

The Bending Process

Convex Glass is made by laying flat glass into frame molds and heating the glass to temperatures that allow the glass to slump. Longer heat creates a deeper bend. Most bends are between 3/4" and 1" deep.