Practice Silicone Caulking Before Getting to Work

Installing silicone caulk can be tricky. Try to squeeze out the exact amount you need.
Installing silicone caulk can be tricky. Try to squeeze out the exact amount you need. (By Tim Carter For The Washington Post)
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By Tim Carter
Saturday, September 13, 2008

DEAR TIM: Caulking is not my favorite job, but I have to use silicone caulk to fix a leaking shower enclosure. Can you offer any tips on caulk removal so I do not damage the metal or the marble curb? What is the secret when working with silicone caulk? I always end up with a mess. -- Beth S., Sarasota, Fla.

DEAR BETH: Silicone caulk is a fantastic product but not necessarily user-friendly. It can certainly create a mess -- and be very careful if you wear contact lenses. The fumes as the caulk cures can irritate eyes. Make sure to read the safety label on the caulk tube before you use it.

I recently had to do a nearly identical job in a house I just purchased. The silicone caulk joint between a marble threshold and the aluminum shower enclosure had failed. To make matters worse, the tile setter had placed the marble threshold so it had a reverse tilt. Water would pool against the aluminum frame instead of rolling back into the shower. This little bit of hydrostatic pressure caused the water to seep under the aluminum frame and soak the adjoining wall.

Years ago I discovered that to successfully caulk tubs and showers, the joint that is to be caulked needs to be dry. I have a feeling the previous owner knew about this leak, as it appeared the joint had been caulked multiple times but with little success. My suspicion is the repairs never worked because the silicone caulk was not able to make a good bond. Water was trapped under the aluminum frame and seeped out as the caulk was applied.

I was lucky and was able to use another shower in the house so the leaking one could dry for weeks. If you can't do this, think about getting ready to do the repair just before you go on vacation. When you get back, install the silicone caulk on a dry joint.

Caulk removal can be tough. I had great success with an old-fashioned straight-edged razor blade. I was able to hold the blade at a very low angle, slicing between the old silicone caulk and the marble. This didn't cause any scratches. I then cut down through the old caulk with the blade as close to the aluminum frame as possible without touching it. The beads of old silicone caulk peeled off the shower like a strand of spaghetti being pulled up from a plate.

I then used some rubbing alcohol to clean the marble and the aluminum frame, making sure both surfaces were clean and bone dry. Caulk is really an adhesive, so it works best when surfaces are very clean.

Because I have caulked things for years, I knew how big to cut the tip of the new silicone-caulk tube. This is very important. Make the diameter of the hole no larger than 1/16 th-inch wide. Do this by cutting the tip of the tube in small passes. It is easy to cut the hole too large.

To get professional results, squeeze the caulk from the tube slowly and evenly. A good caulk gun does this with ease. Inexpensive caulk guns will cause you nothing but headaches. A great caulk gun usually costs double or triple what a cheap one costs, but it is the best money you will ever spend on a tool.

The trick I have used all these years is to apply just enough silicone caulk that, when I immediately smooth it with my finger, no excess caulk oozes out around my finger onto the surfaces. Because we all have different-size fingers, you will need to experiment to determine how much caulk works with yours.

Make a test corner using two scrap pieces of ceramic tile. Glue them to the inside of a low cardboard box. Start practicing on these mock-ups until you master the technique. It is not as hard as you might think. I like to caulk a strip about two feet long before wiping it with my finger. Be sure to have paper towels on hand to clean up any accidents.

Tim Carter can be contacted via his Web site,

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