For the homeowners and the craftsmen alike an incredibly valuable skill to learn is window glazing. I can’t stress enough how valuable it is. So many contractors will come to do an inspection and see a hint of rot or glaze that is cracking and falling out and say, “Oh yes, you definitely need new windows” Suddenly you will be looking at between one and two thousand dollars per average sized window that definitely needs to be replaced. Some of you may have already caught my “do it yourself wood rot blog.” That goes for windows too. It is the same procedure and you will usually find rot in the corner of the bottom rail where it meets the stile. I should probably explain the parts, huh. The top rail and the bottom rail are what they sound like. It is the piece of wood at the top or the bottom of the window. The stiles are the pieces of wood on the left or right. The glass is surrounded by rails and stiles. They hug the windowpane(s). If there are divided panes the wood in between are called muntins. Okay back on topic: The point I can’t stress enough is that if you have the time to do home projects, doing this yourself can potentially save thousands upon thousands of dollars. Ready?
All you will need for supplies is matching paint, an oil based primer, a good putty knife or two, and window glaze. All this shouldn’t come to more than about a hundred dollars.
The first thing to do is examine physically the old glaze. You can do this with the corner of a putty knife, but I use a cheap, old beater pocket knife for this because I find that the rigid triangular shaped point is a bit more effective. What you want to do is prod a crack and see if it pops loose even a little bit. Then pick at it until it all falls out. If it is hard and adhered well enough, just leave it in. If you can get under it, pick it out. It is best to stay between the wood and the glaze and not the glass and the glaze. You can, but, be careful. The only thing keeping this job inexpensive is your care not to break the glass. If you put pressure on the glass itself, you could crack it and believe me, it will happen on occasion and when it does, it is heartbreaking. It is even more heartbreaking if it is old wavy glass. **uncommon knowledge Old wavy glass is not flawed from years of distortion. Those are imperfections of the glass being made by human hands that have been there since the birth of that pane of glass. No two are alike. They don’t make them with personality any more.** After all the loose glaze is out, dust or vacuum really well. Get the surface free of debris.
You can use the oil based primer to seal the newly exposed surface of the chipped glaze and dried wood frame next to the window. I like to use a general wood sealer that also works with glaze just because it has a faster dry time and when I am out on the jobsite I have to keep moving.
Glaze is not expensive at all but it takes a delicately intuitive touch to work with it and a little knowledge about it could guide your hand. It is both temperature and moisture sensitive. It is an oil based product and it flows through it so there will be portions that are stickier than others and want to smear all over. One trick I learned from my mentor that helped me greatly was the starch trick. A sprinkle rubbed into the palms of your hand will make a damp, sticky, separating glaze, much more manageable. Don’t use too much or your new glaze line wont seal the window properly. It needs to remain a little bit sticky.
If it is cold it will be hard and not easily workable. On a hot day this step will go very fast and might not even be necessary. Knead it. Like dough. Smash it, and work it. Roll it into a ball. Do this as much as necessary for it to become soft and mushy.
Between your palms pinch roll it by pressing it back and forth between the heels of your palms so that it snakes out. I usually aim for roughly a quarter inch diameter snake. This is roughly the volume per inch of a good glaze line plus excess for cutting, but we’ll get to that in a bit.
Lay the snake into the crack between the wood and the glass gently pressing it in with a thumb or finger. If it isn’t sticky enough because you used too much cornstarch on your hands this is when you will discover it. If it doesn’t want to stick start over and make it again slightly stickier. If you force it in with out it naturally sticky it won’t last very long. It should stick and dry that way. That stickiness is the glue that bonds it all together. The starch is good for making it manageable when it is too sticky to work with, so you can get away with some, but if you over-indulge your work will show it in the years to come.
Put the blade of the putty knife against the glass laying it flat on the bead of glaze you laid out. Press the glaze in hard. It should squirt out from under the edge of the knife a bit as you do this. I like to overlap each new blade press by about half a blade width for consistency and to make damn sure I got it all in there really good without missing any spots. You want to be able to imagine that you left no open pockets unfilled with the glaze underneath the surface. The squirting of it from under the blade as you retract away id a good indicator that the material had nowhere else left to go but out from under the knife. This is by far the most crucial and exhausting part of glazing. If your forearms aren’t sore by the time you are done with a pane of glass, you weren’t doing it right. I do this all the time and mine still get tired from it.
Now to make it look clean it is all about the correct angle. You will need your putty knife and a steady hand. I dig the corner in gradually until I find the edge of the wooden rabbet that was cut for the cavity of the window on the opposite side of the glass. That is the line you want to follow. It is straight and in just the right spot. The top of the blade should rest right on the wood edge on the face of the window. The blade should be as flat as possible laying parallel to the cut line. Press down in that position and drag it keeping an eye on the corner of your knife. You are freehand cutting it and tracing that line on the underside of the glass. There should be a smash-like cut at the face edge of the glaze and a slice cut at the glass edge, both leaving a small wrinkly cut line of excess glaze material. This might take some practice, but you know what? It is no big deal because glaze has a working time of several days so if it doesn’t work you can dig it out and do it all over again with no waste other than some time.
After you get a good cut you will carefully scoop away the excess with your putty knife. If you accidentally dig out your glaze, well bummer, but just press it back in and cut again. If you merely nick it, don’t sweat it unless you are an anal perfectionist. I can relate. Only if I am in a real hurry will I not fix this by doing it over.
I also will sometimes use the excess as a woodfiller in little cracks and flaws since I have it out. There is no harm in filling a crack. Glaze was the wood filler of the old craftsmen before manufacturers started making advanced products. Works perfectly well too. The only reason I wouldn’t use I in any other situation is the setting time. But since we are already waiting for it anyway, just fill it with glaze.
Another trick is to put another dab of starch in your hands and ever so gently massage the line with your finger tip, by dragging out any tiny flaws. Glaze is extremely malleable so why not take advantage of that? I even do this to smooth out the vibration ripples from the blade not moving perfectly smoothly when cutting.
