How to Replace Foggy Glass

Push against the flexible vinyl channels on spring-loaded double-hung windows to release the channel pins. Carefully remove each window, setting it aside on a flat surface. Repair older-model double-hung windows while still in the window frame. With either type, measure the window frame for new glass. Take the measurements to a hardware store and order new glass.

Apply a heat gun to the old window glazing to soften the putty on older-model windows. Avoid scorching the wood frame. Slowly scrape away the old putty once it softens, using the putty knife. Take the putty knife and carefully pry out the vinyl glazing strips on newer-model windows.

Remove the foggy glass and metal glazing points from the frame. Clean the L-shaped grooves of old paint and putty by sanding down the frame. Paint the wooden window frame with a heavy coat of linseed oil to keep the oils in putty, making them last longer by staying pliable. Allow the linseed oil to dry.

Place a thin layer, about 1/16 inch, of glazing compound or putty around the window frame with the caulking gun to add an extra cushion for the glass to sit on and seal out air leaks. Insert the new glass into the window frame. Press down on the glass lightly but firmly.

Install the new glazing points every 10 inches using the tip of the putty knife. Slide the putty knife sideways and avoid using downward pressure when inserting the glazing points; downward pressure can break the glass. Seal the glass by applying the glazing compound to the edges of the glass along the frame. Smooth down the glazing with a soft cloth or wet finger.

Look at the painting instructions for the glazing compound; latex glazing allows for same-day painting. Improve the window’s weather seal by overlapping the paint onto the glass by 1/16 inch. Use at least two coats of paint on the outside portion of the window. Let the paint dry. Remove any excess paint with a razor blade scraper. Run the razor blade scraper 1/8 inch along the edge of the putty.