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After trying different products on my horse trailers seams and the pop up vent, and it would still leak, this product took care of it perfectly! Bought more to finish the entire trailer over!

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Purchased this to repair my 9 ft. aluminum hull RIB. The transom was poorly glued from the manufacturer and separated from the tubes. I needed an adhesive that had not only good adhesive characteristics but the ability to stretch in the joint to handle the various pressures in an inflatable goes through during the many heating and cooling cycles in a day. Product was used on the tubes and the aluminum "cups" built into the transom. Careful cleaning, clamping and ample curing times seems to have yielded a strong bond. Don't try to rush the product. Follow directions.

This is the area that the Sika was used in. The "cup" measures about 6" x 12". The Hypalon tube setinto the cup and then gets trimmed with Hypalon strips that were conventionally glued with Clifton Adhesive.

This stuff is awesome. If you roughen up the surface it will bond to almost anything. The only thing it is not recommended for is Masonary and Concrete. There are better products like NP1 by BASF. This stuff can be messy but you would expect that and acetone or lacquer thinner takes it off no problem. Any solvent thinner will actually clean it up but acetone or lacquer thinner are the best for cleaning the surface before application because they don't leave any residue. Don't buy more than you need of the 221 but if you have an old tube that the end hardens up on, just poke a hole below the cured area and squeeze it out. Tape over the hole and work your way down the tube. Store in a dry place as this stuff is moisture cured. Needs a couple of days at least before painting over to be safe. Moisture and temperature will determine this. I warm the tube up before using it either in the sun or with a heat gun and it really helps with the flow and application. Heck I use some of this to put part of woodstove door gasket back in place and it is still there. Totally violating what this product is made for. If you had to have one tube of sealant around, this would be the one. Always have a tube in my shop. You will not be disappointed with this product.

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Used it to put a back window into a convertible. Good, but messy, goop.

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We replaced a bulkhead that butted up against the side of the house. That edge had about a 1/4" crack that needed to be sealed. At first, we tried caulking the edge, but the caulk failed and leaked from the rain and the runoff from the roof. I searched around and found the Sikaflex product which is advertised as a marine sealant. So, I tried using the Sikaflex in place of the caulk. The product worked great. It can fill and seal a much larger crack than caulk can and it has proven to be totally waterproof. It also spreads uniformly and isn't unattractive.

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This was for doing seam along gunwhale. Taped gunwhale and deck using 3M 2090 blue tape and then used a small teaspoon as tool, and gloved finger in tight areas. Used soapy water as tooling agent with great results. Did about 3 foot sections and moved steadily along. When satisfied, pulled up tape immediately. Used alcohol immediately to clean up any accidents. Looks great.

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Unlike 5200, hardware can be removed without damaging the points of adhesion. While it can be used underwater, it's best uses are for bedding pretty much anything on a boat. As it dries to a rubbery consistency you can even use it to mount pumps to flat dry surfaces, including bilge pumps and float switches. Excess can be left on to dry and then can be trimmed and peels off. It sands very well and can be color matched with your favorite paint.

Verified Purchase

Wish I'd purchased the white version, but this stuff works well as a long term sealant on any application that involves movement. I used it on my RV, and it holds up well against the weather as well as against the motion of a Motorhome in transit.

sealed slideout in RV

Great waterproofing product. Excellent sales experience.