Tag Archives: stop leaking seams

When you’re making a boat cover, outdoor storage cover or tarp, you want to be sure that it will keep your possessions safe, clean and dry. But did you know that when you sew, the holes the needle creates in the fabric can leave your cover susceptible to leaks? If you’re concerned with leaking seams, never fear. Today we have some helpful tips for ways you can seal up your seams to keep them as watertight as possible.

Sew with Antiwick Thread


Testing Anti-Wick Thread’s water resistance

If you’re sewing a new project, you can add built-in protection from leaks by using an anti-wick thread. Antiwick thread is a bonded Dabond polyester thread with a wax coating that was specifically designed to prevent weeping seams. The way Antiwick works is that the wax plugs the stitch holes to prevent water from leaking through. It’s the same V-92 polyester thread that most marine fabricators use, just with an extra coating so it’s still UV, mildew and abrasion resistant.

Use a Seam Sealer


For those who already have thread to use or would like to waterproof the seams on an existing cover, you can use a topical seam sealer. We recommend using Iosso® Seam Sealer on cotton, polyester, Sunbrella and other synthetic woven fabrics. This seam sealer will effectively protect and seal your seams without changing the look and feel of your fabric. Iosso Seam Sealer comes with a sponge applicator for easy application directly to your sewn seams. You’ll get the best results if you apply the seam sealer to both sides of the seams. Seam Sealer should be re-applied periodically if your cover sees a lot of harsh weather and after each cleaning.


To protect seams on a vinyl tarp or cover, you can use HH-66 Vinyl Cement. as a seam sealer. Just carefully brush the HH-66 right on top of the sewn seams on the underside of the fabric only. The glue will dry clear and after it has cured it won’t be sticky.

You can find all of these great waterproofing products at

Have you had problems with weeping seams? Have you tried any of these methods? Share your experiences with us in the comments!

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