14. Mix Putty for Leaded Glass Windows
One of the questions we hear most often—right after “how do I load the hand foiler?”—is about our recipe for puttying our leaded glass panels. Since it comes up so frequently, we thought it would make the perfect blog topic. In this post, we’ll walk you through the supplies we use and how we mix our putty.
Why do you need to putty leaded windows?
The glass, lead, and putty all work together to form a strong and stable stained glass window. Before the putty is applied, you can often hear the glass rattling inside the lead channels and the whole panel may feel wobbly. Once the putty is worked into the lead channels, the glass is held in place, eliminating any rattling and reinforcing the lead. Puttying also stops water from being able to come in through the lead joints. The result is a solid, long-lasting stained glass window.
Ingredients to make putty
- Whiting Powder (Calcium Carbonate)
- Linseed oil (Boiled)
- Solvent (turpentine, paint thinner, or odourless turpentine)
- Black concrete pigment
Tools for cleaning the window during and after cementing
- Cement Brush
- Lathekin Fid
- Luster brush
- Dental picks / skewers
- Cloths
Our typical mix
- 1 part boiled linseed oil
- 1 part solvent
- Add whiting to consistency of thick icing
- A small amount of pigment to turn the mixture dark
It will require a lot of stirring to get everything to blend together. Add more whiting if the mixture is too thin OR add more solvent/oil blend if it is too thick. Add small amounts of pigment and stir until the mixture is the desired colour. Typically putty is a dark colour. After you mixed a batch of cement, leave some out in a cup and note how long it took to harden up so you can get a better understanding on your cement mixture dry times.
Don't want to mix your own? You got options!
There are pre-made putty mixes for leaded glass windows. If we are doing an on site repair or just need a small amount we will reach for the Glass Pro brand. Shop for it here. We personally find this putty too thick to work with straight out of the jar so we will take what we need out of the jar and mix it with solvent to thin it before applying it to the window.
Tips
- Be sure to clean your cement brushes well once you finish cementing to get more use out of them! We will often leave them in a jar of solvent and put a lid on it to soften the putty inside the bristles
- Highly recommend a luster brush to save you time on polishing
-
Do not leave the putty on the window and take off bulk of the cement within a couple hours of applying it. It becomes really hard to get off especially if it dries in textured glass. (Speaking from experience 😂)
Thank you for reading & happy leading!
With gratitude,
Lucent Glass