How to Remove Old Acrylic Caulk From Windows

Whether you are putting in new windows, or simply weatherproofing current ones in your home, you will first have to remove the old caulk.

This job is not something anyone looks forward to, but it will be easier if you have the right tools and a chemical caulk softener. This softener can save a lot of muscle power and is especially helpful if the old acrylic caulk seems hard as cement.

Brush the old acrylic caulk and around the window ledge with a dry paint brush to remove loose dirt.

Apply 3M Caulk Remover, or a similar, all-purpose caulk remover, to old caulk and then let it sit for at least two hours. Be sure to follow directions on the bottle as different products may require different times.

Push blade of putty knife or a caulk removal tool beneath caulk to test for softness. If it is, gently scrape off all the old caulk.

Wipe away any remaining caulk or caulk remover with a wet shop cloth.

Dry the areas that are now free of caulk with a dry cloth. Brush away any remaining debris with a dry paint brush.

Things You Will Need

  • Caulk softener (3M Caulk remover)
  • Putty knife or caulk removal tool
  • Thick bristled paint brush
  • Water
  • Shop towel or sponge


  • You may need to leave caulk remover on longer than two hours. If you use a chemical caulking remover before trying to remove caulking, often a small butter knife will work just as well as a putty knife or similar tool.


  • Wear eye protection to avoid injury in case pieces of caulk or other debris fly up during removal. If you use a sharp-bladed knife, wear protective gloves and use both hands to hold the tool. When removing caulk from around old wooden window ledges and sills, use slow, gently but firm movements, rather than hard, jerking thrusts, to remove caulk or you risk the blade slipping and damaging the wood.