Window Repair Process

Progress & Descriptor – Start to Install


What goes into repairing these wonderful pieces of our history? Here are some terms and photos of the process:

Lead Came – Came is the lead strips that wrap around the individual pieces of glass. Came comes in various widths and profiles.

Stained Glass – Originally referred to glass that was treated with “Silver Stain” which actually stained the glass a yellow or dark amber color.  Today the term has come to mean most any colored window or craft glass.

Solder – To solder is to join the lead came where it meets. The solder material is a low melting alloy made up of lead and tin.

Flux – Flux is a material (either paste or wax) which is applied to the lead came. The flux cleans the surface and allows for a better bond between the metals.

Stained Glass Putty – A mixture of calcium carbonate, linseed oil and often some type of colorant (stove black). Once combined, these ingredients form a thick paste that, when forced between the lead came and glass, forms a solid barrier against moisture.  It also has the effect of strengthening the window as the putty dries and become firm.

Chestnut Hill, MA

1900s Home

This window is one of six that came out of a home in Brookline, MA built in the 1900’s. The windows are all original. At some point in the home’s history the decision was made to paint the lead came white, I am not sure why this was done but it’s not entirely uncommon.

A Closer Look...

A closer look shows just how damaged this window is. The lead came (painted white) has become brittle with age and cracks have begun to form at various stress points. The stained glass putty has long since broken down, as evidenced by the buildup of calcification…proof positive that moisture has made its way under the lead caming.

Our next move is to remove all this damaged lead and clean the old glass. But first, it’s a very good idea to either number the glass pieces and/or do a charcoal rubbing of the window. This additional step is not so important for a simple window like this one, but it’s absolutely vital if you are rebuilding a more detailed window.

Blackwells Glass RestorationCloserlook

Restoration Commissions

With the rubbing complete, it takes a little bit of pulling with my hands for this window to begin to come apart. You will want to take care at this point as disrupting the came will cause any remaining putty to come loose as well. This dried and now powdery putty is full of lead toxins, the result of the lead leaching into the putty. I recommend occasionally spraying water onto the glass and came as the lead and calcium buildup is being removed, to help prevent the putty dust from aerosolizing. Be sure to follow up with a thorough vacuuming of your work area with a HEPA-filter shop vacuum.