How to Glaze Windows Using a Caulking Gun
It used to be that glazing windows required a specific type of putty that needed to be applied with a putty knife, but since new types of products have been invented that allow the use of a caulking gun, glazing windows has become a much easier, cleaner job. You'll need to decide which type of putty you want. Latex dries faster and lasts longer, but oil is cleaner and easier to work with. Which you use depends on how neat and fast you need your windows done. It still is easier, depending on the height of your windows, to remove them from your building completely, however it is not required. It just depends on how many windows you need to do and how comfortable you want to be while you do it.
Step 1 - Remove the Old Glaze
Before you can apply any new glaze product, the old putty must first be removed. You can do this with the putty knife, gently working it off. If you run into spots that are tougher than others, you can melt it off using a heat gun, or if one is not available, a blowtorch and a hot piece of metal, though if you do that, be careful to avoid touching the window glass itself. The high heat can cause it to crack. Also, you can use a grinder attachment for a drill, but again, be careful to watch the glass.
Step 2 - Prepare the Area
Before you can apply the new glaze, you first need to apply a coat of primer. This ensures that the glaze will effectively stick to the surface you apply it to. Before you apply the primer, clean off the area the old glaze was in. You can either wipe it down with a towel or use an alcohol-based cleanser. In either case, the area needs to completely dry before you apply the primer. You don't want the layer to be too thick. Just use enough to cover the area. Once it's dried, you can apply the glaze itself.
Step 3 - Apply the Glaze
To apply the glaze, squeeze a stream from the caulking gun into the corner of the window, where the glass meets the frame. You don't want the stream to be too thick, but you also need enough to adequately spread out and cover the necessary area. Once you've applied a suitable amount, take the putty knife and spread it out, pushing the glaze flat and into any nooks and corners. It doesn't have to be perfect; as long as there are no open spaces, it will be fine.
Step 4 - Painting
Once the glaze has dried completely, apply another thin coat of primer, and a coat of paint, as well. These layers will protect the glaze and keep it safe from the elements.