Before you can add caulking to your windows, they must be clean of debris. If you have older windows that you're weatherproofing or replacing, you will probably need to remove any old acrylic caulk that's damaged or peeling away first. Follow these instructions to make this task simple and easy.
Step 1 - Prepare the Yourself and the Area
Always make sure that you are safe before starting any DIY project. Wear gloves to protect your hands from accidents with the knife or razor blade and to protect you from blisters if you have many windows to clean up. With a caulk softener or remover, less elbow grease will be required, but blisters may form if you are doing a lot of work without protective gloves.
Cleaning the window of all other debris, besides the sealant, is also important. Brush off the dirt and dust from the window sill and old caulk with a thick-bristled paintbrush.
Step 2 - Apply Caulk Remover
Although you can scrape off caulk without using a remover, this chemical product will make your job much easier. Apply an all-purpose caulk softener or remover to the sealant that you want to remove, and leave it to sit for at least two hours or for as long as the packaging instructions recommend. If you are against using chemicals, simply dampen the caulk with water and/or rubbing alcohol before scraping instead. Test the caulking after the allotted time; if it doesn't remove somewhat easily, put more solution on it and let it sit for another half hour or so.
Step 3 - Remove Caulk with Knife
Now the work begins; although the caulk softener will have made the effort more minimal, this will take some elbow grease to accomplish. Push the putty knife under the sealant and scrape it away from the sill. Different sizes of putty knifes are helpful as they will allow you to more easily remove small pieces that may be wedged in corners.
Step 4 - Remove Sealant from Glass
To remove old caulk that may have gotten on the windows themselves, first soften it with a damp sponge. Then, using a razor blade, scrape towards the window edge. Hold the razor blade as level as possible with the glass and scrape the caulk off from where it meets the window. Dampen the area often as you scrape in short, even strokes. Any remaining residue from the caulk on the windows can be wiped off with a cotton ball soaked in rubbing alcohol.
Step 5 - Clean off the Area
After all the old sealant has been scraped off, wipe down the area with a dampened sponge to remove crumbs of caulk and and caulk softener that may be on or around the windows. Now that the area is clean and free of debris, wipe everything down with a clean, dry cloth. Finally, brush off any remaining bits of dry caulk residue from the window sill and edges with your thick-bristled brush.