Caulk Talk Page 2

Caulk Talk
Caulk Talk
Part 2: Picking the right caulking product for the job, and more.

By Capt. Patrick Sciacca — April 2001
 More of this Feature
• Part 1: Caulk Talk
• Part 2: Caulk Talk continued
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• Maintenance Editorial Index
• Maintenance Q&A Index
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• Rule Industries
• Sika
• 3M
• Boat Life

Once you determine what needs to be recaulked, how do you know which sealant to use? Picking the wrong product not only can be inconvenient, but also can cost you big money. For instance, Tilders says that for areas below the waterline, silicone is difficult to use because it creates large beads that may not cure correctly. Instead he advises using a polyurethane, vinyl, or polysulfide sealant for these areas. Polyurethane caulks are tremendously effective, but because their bond is so strong, they can be difficult to remove, and trying to do so can result in damage to the materials to which the sealant adheres, especially wood and fiberglass. For that reason polysulfide caulk is the favorite when working with a teak deck; it is the most chemically resistant, least likely to break down from exposure to teak cleaners and oils, and can be relatively easily removed when you need to. (As with most surfaces, teak decks must be extremely clean or the caulking will not adhere to them.)

Or take plastics such as ABS and Lexan. Many kinds of sealants could fit the bill here, but there are some you should avoid. Polyurethane and polysulfide caulkings could fracture the plastic over time and leave you with a more expensive proposition then you originally envisioned.

But choosing the right caulk is only the first step. To get a good result, you also need to apply it correctly. How can you be sure that your next caulking job doesn't end up looking like mine? According to Tilders, my first mistake was simply not paying attention to the directions. (I guess it's a male shortcoming.) He tells me that virtually all sealants come with great directions, and following them is critical, since many applications demand certain techniques. (Most of the time you can rely on the instructions printed on the container, although many companies have Web sites containing complete product information.)

For instance, if you're using caulking as gasket material, the directions will instruct you to apply it, position the part, fasten the part to about 75 percent of full tightness, allow the sealant to cure, and then fasten it the rest of the way. This will create a better seal, since you won't be squeezing out uncured sealant and leaving gaps between the two surfaces. When caulking a seam, the preferred method is to push the caulk, not pull it. This technique ensures the seam is filled correctly. And regardless of which caulk you use or what application you use it for, always check the directions for standard cure times and adjust them according to the environmental conditions (mainly temperature and humidity) in which you're working.

Despite my dysfunctional youth I learned that you don't have to be a rocket scientist to know what type of caulk you need and you don't have to be Picasso to place an effective bead of caulk on your boat. Just follow the manufacturers' product and application recommendations to the letter. Then all you have to do is look around for something loose, leaking, or even slightly suspicious and reseal it.

Rule Industries (978) 281-0440. Fax: (978) 283-2619.

Sika (201) 933-8800. Fax: (201) 933-6225.

3M (877) 366-2746.

Boat Life (800) 382-9706. Fax: (843) 566-1275.

Previous page > Caulk Talk, Part 1 > Page 1, 2

This article originally appeared in the May 2003 issue of Power & Motoryacht magazine.

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