How to Reseal Double Pane Windows
- 1). 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.
- 2). 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.
- 3). 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.
- 4). 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.
- 5). 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.
Source...