How To Clean And Waterproof Marine Canvas, Part 1


Marine canvas is one of those parts of the boat that get exponentially harder to clean and restore the longer you wait. The best advice is to wash it often, gently, with boat soap, and soft brush, and plenty of fresh water. This will keep contaminants off the fabric, and discourage any mold, mildew, or algae growth from forming on the surface.

But that’s only the first step of what I have discovered is a system of maintaining marine canvas, and over the past year of experimentation, I have learned a few lessons that will help you add years to the life of your marine canvas covers.

First, regular washing is hugely helpful, but the real trick to keeping canvas clean is maintaining the waterproofing that is preventing water… and contaminants, mold spores, etc… from entering into the fabric itself. Of course “waterproofing” is a misnomer, we really mean keeping it water-resistant, but even good water resistance will prevent water from entering the fabric any farther than the very surface, and prevent all the other junk from entering as well.

While we call it canvas, today’s marine canvas is a synthetic woven fabric, many times made by a company called Sunbrella. While the fibers won’t rot like true cotton canvas, the weave of the fabric provides plenty of places to catch and trap contaminants, and give mold, mildew, and algae a great place to live. Sunbrella does a very good job of preventing this though; new fabric has a robust, factory applied waterproofing that beads water like crazy, and will last 2 or 3 seasons before needing replenishment.

Replenishment is truly a need however, and one that most boat owners neglect. Without applying a good waterproofing spray to maintain ample water resistance, your canvas’ life clock starts ticking down the minute that factory waterproofing is gone.

Stay tuned for Part 2 where I explain the process I went through to learn how to clean and re-waterproof effectively, and how I settled on what I believe is the best, and most environmentally responsible method for my clients.

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