A double-pane window holds certain advantages over traditional windows. It is composed of two sheets of glass separated by less than an inch of space that is vacuum-sealed to prevent heat loss and condensation and even to muffle street noise. The glass panels of a double-pane window share a single frame that requires a proper sealant for further insulation. A silicone caulk can accomplish this effectively if the existing seal becomes damaged or worn over time.
Dissolve the existing sealant using a commercial caulk remover. Apply the solvent according to manufacturer's instructions, then allow it to soften the old seal for the amount of time indicated on the product label.
Cut the treated sealant with a utility knife to loosen it from around the window frame. Pry it from the seams with a putty knife to remove it completely.
Use scissors to cut the tip off a cartridge of silicone caulk. The resulting opening should be no larger than 1/4-inch wide, the standard size for a bead of caulk. Puncture the seal within the nozzle using a thin, stiff object.
Load the cartridge into a caulking gun and apply a bead of the silicone into a joint in the window frame, where it meets the wall. Squeeze the trigger steadily and draw the tip of the gun across the seam until it is evenly filled.
Quickly glide a wooden craft stick over the freshly applied silicone for a neater seal. The caulk will dry overnight, or after a full 24-hour period.