Window Glazing and Puttying

Technically, and traditionally speaking, to glaze a window is to install glass. Glazing is actually referring to installing the glass itself.   Then glazing compound, or glazing putty, is applied.  Unfortunately, the application of glazing putty just isn't a skill learned by most painters and tradesmen anymore.  Multi-stepped, proper preparation is usually the most important step to having a good looking, long lasting putty job. Having used several oil-modified and water based products over the years, I've settled on Sarco glazing putty and found it to be the best out there (and the most used and trusted by restoration specialists across the country).  It is a traditional linseed-oil putty that has great workability and retains the ability to flex and move with the natural movement of our windows in South Louisiana's climate.

 There are several important steps to a good, lasting job.  Once the old putty is removed, the sash must be sanded and primed with a penetrating oil primer or boiled linseed oil before re-application of putty.  If not, the wood will wick out the oils from the putty and it will dry and crack prematurely. After the putty has developed a skin, a top quality waterborne or latex paint is applied.  An important step here is to seal the putty by drawing a line onto the glass about 1/16".  A skilled painter can do it and have it still look beautiful. Unfortunately, I see so many sloppy paint jobs where the protective seal was cut away when they cleaned the paint from the glass.  This reduces the life of the putty.

Another important part of the glazing process is back bedding the glass in a cushion of putty (or caulking is a more modern way too). The back bedding in older windows deteriorates over the years, but never gets redone as the glass must come out in order to do so. Without that cushion, the glass is susceptible to movement from things like thunder, air conditioners, swelling and contraction of the sash itself, and even opening an closing the doors to the house. This greatly influences the life of the putty and the job it performs in keeping water out.

Glass

Our glass shop carries single strength and 1/8” annealed modern glass. We also stock Antique or wavy new glass made with the same methods as it would have been a century ago. We do keep reclaimed glass around when it isn’t too badly scratched up. A majority of windows have had their glass scratched over the years from people sanding and painting the windows. During the restoration process, the glass comes out and its usually a good time to explore the option of just replacing it with new glass. Once a window is restored, clean, and the putty line is moved back to where it is supposed to be, all of those scratches tend to show louder and can be a bit ridiculous. It’s painful for me to put glass back in that has lots of deep etching from sand paper or swirl marks from orbital sanders.