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Always Remove Old Caulk Before Applying New
The first step in applying new caulk around your bathtub, shower, or sink is to remove the old caulk. New caulk doesn't stick to old caulk, so if you fail to remove the old stuff, the new caulk can't form a watertight seal, leaving the potential for moisture to seep into areas where you don't want it.
There are a few different tools you can use to scrape and strip off the crusty, moldy old caulk. You can also try a chemical caulk remover, if you don't mind waiting for it to work. And take heart: If you just get in there and start scraping, you'll find it's not as bad as you had feared.Continue to 2 of 4 below.
02 of 04
Using Chemical Caulk Remover
One easy way to start the process of caulk removal is to use a caulk removal solution, such as the products made by 3M, DAP, and other brands. This chemical remover destroys the bond between the old caulk and the tile, tub, or sink, making it very easy to pry out of cracks and crevices.
A small bottle of liquid caulk remover costs less than $10 and will remove about 20 linear feet of caulk—enough for most bathtubs. Follow the manufacturer's instructions for use. Here is the general procedure:
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- Squeeze remover onto the old caulk so it is covered completely.
- Let the remover set as directed by the product's instructions. Some users report that it helps to allow the product to set overnight for maximum effectiveness.
- Use a plastic putty knife or other tool to scrape away the old caulk. If possible, try to peel it off in strips as you scrape.
- Inspect the area thoroughly, and remove any caulk residue with the tool.
- Clean the surfaces thoroughly with a clean cloth moistened with rubbing alcohol. Let the surfaces dry completely before applying new caulk.
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Using a Caulk Removal Tool
Several manufacturers make caulk removal tools, which sometimes come in kits that include tools for applying and smoothing new caulk. The better tools are made of plastic or polished steel that won't scratch surfaces and have angles and blades designed to scrape caulk out of narrow crevices and corners. One excellent tool from Hyde has a corner scraper blade that is reversible and replaceable to ensure you always have a sharp tool.
Caulk removal tools can be used by themselves, but they are also great as the second step after applying chemical caulk remover.
After scraping out the old caulk, inspect the joint to ensure you've removed it completely. Before applying new caulk, clean the surfaces thoroughly with a clean cloth moistened with rubbing alcohol, and let the surfaces dry.Continue to 4 of 4 below.
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Using a Razor Scraper
Another tool that works well is a good, old-fashioned razor scraper, also known as a Widget. The trick here is to use a very sharp blade and to make sure the blade edge is flat on the surface to prevent scratching. A razor is ideal for getting behind thin smears of old caulk.
In general, it is best to scrape behind both side edges of the caulk bead to separate it from the surface, then try to peel it off in long strips. Be careful not to let the corners of the blade contact the surface, to prevent scratching; keep the tool at a low angle—almost flat to the surface—at all times.