General Maintenance

There is almost always more than one way to do anything on a boat, and that includes marine canvas. Craftsmanship, technology, ingenuity, intended use, environment, and tradition are all involved. We get lots of questions about canvas. Opinions and practices may vary somewhat, but the points covered here will keep you on the right track… feel free to call/email us with questions or comments.

Care, Cleaning, & Repair Tips


Boat Covers
If the cover is a coated fabric, regular rinsing with fresh wash is normally all you need to do. To remove dirt and bird stains, use a mild detergent and soft bristle brush. Do not use harsh cleaners or brushes, since these will shorten the life of the fabric coatings. If the coating is a woven acrylic material such as Sunbrella, see above for the latest cleaning recommendations.


Vinyl Windows (“Isinglass”)
Top quality vinyl windows are surprisingly expensive. But cared for properly, you should get years of service from them if they were good quality to begin with. The most common signs of degradation are crazing or cracking, brownish discoloration or cloudiness, brittleness, or surface chalkiness. When they start to go, they go fast!

Why is this? From the moment it is made, vinyl constantly “evaporates” plasticizers from the surface. Over time the vinyl exhausts it’s internal plasticizers, dries out, discolors, and finally becomes brittle. Damage is hastened by contact with liquids such as harsh cleaners and polishes. Polishing at this point has limited value in restoring the window- it has literally dried out from the inside.

Proper care is essential to long life. This includes regular rinsing of salt spray and debris, periodic cleaning with a soft cloth (no paper towels), mild detergent, and warm water. Heat and harsh UV (sunlight) exposure hasten deterioration significantly. Never use any kind of product with silicone in it on your windows, and don’t handle the glass with sunscreen on your hands.

  • What exactly is “Isinglass”?

“Isinglass” (also spelled “eisenglass”) is often misunderstood as well as misspelled. Isinglass is a name that has been used for centuries to refer to thin sheets of the soft mineral “mica”, which was used as windows in houses & carriages, as well as naval ships of war. It let light in while being flexible enough to withstand damaging vibration or impact.

Today, the term is used generically to refer to the clear window material, usually vinyl, found on boats. It’s not some mysterious specialty product, although good marine vinyl like coated Strataglass is indeed specially manufactured for marine use.

So your vinyl windows aren’t technically isinglass (mica)- they’re vinyl windows!

Today’s best marine vinyls have top coatings to reduce plasticizer migration, but the top coatings need to be preserved to do their job. The best prevention is to avoid scratching, rubbing, or folding the windows as much as possible, to avoid harsh chemicals and brushes that destroy the top coatings, and to periodically restore the protective film with a recommended product.

Keeping the windows under cover, whether a whole boat cover or individual snap-on covers, can extend their life considerably. If your boat’s vinyl windows will have full exposure for long periods, an investment in canvas window covers will pay back many times over.

For non-Strataglass vinyls, regularly applying a specialty vinyl protectant like one of the 303 Aerospace products, Plexus, or McGuiars will help.
Strataglass/Crystal Clear 20/20 vinyls are different! They have a special coating that requires special care. As of 9/30/04, the Strataglass company requires use of specific IMAR cleaning and polishing products to maintain the warranty. Aquatech and Collinite products are no longer recommended.


Zippers, Snaps, and other fasteners
Zippers, snaps, and other fasteners carry strong loads. The less stress placed on them during normal operation, the less frequently you’ll have to replace or repair them. Good canvas design will have zippers out of sight behind the fabric for sun protection.

Fasteners should be unsnapped by pulling as close to the fastener itself as possible. Don’t remove canvas by jerking one edge of the material. This can damage the canvas as well as the fasteners.

If fasteners become difficult to work, lubricate them with a commercial product such as Star Brite, IOSSO, etc. These products contain special ingredients like Teflon. Or, you can get by short term with Vaseline, WD-40, silicone spray, even ChapStik…!!

Whichever product you use, be sure not to contact the canvas or any other surface besides the fastener. Silicone will damage the water-repellent coating on Sunbrella, for instance, and it is terrible for your vinyl windows. Broken or missing fasteners can usually be fixed with the proper tools and parts. For larger/tougher jobs, a canvas shop has the industrial-grade materials and tools of the trade to take care of you.


What’s the best way to store my canvas items?
If your canvas is not going to remain on the boat all season, it’s important to spend a minute to store it properly. Three main rules: Clean, dry, and no creases! Clean the canvas and vinyl windows as outlined elsewhere in these pages. Even though synthetic fabrics themselves don’t support mildew, humidity combined with chemicals in the air and organic growths on the surfaces can lead to mildew, mold, stains, marks, and worse… even ruining canvas in a single season. And vinyl windows can stick together, or take a pattern from another surface. So clean first, dry thoroughly, store in a well ventilated area. Try to store large panels flat, with sheets of paper or fabric between the panels so they don’t stick together. It is OK to roll a top or dodger, but watch those creases & folds!


Can I do some canvas repairs myself?
Yes you can. First, you can help avoid repairs in the first place by following a regular maintenance program. Doing so can nearly double the useful life of your expensive canvas items. Second, stay on top of small repairs before they become big. For instance, stitching that is beginning to deteriorate or pull apart can sometimes be fixed short-term by careful use of a home sewing machine and proper materials.

Fastener replacement and small sewing projects can also be very satisfying if you have the time and patience. Major repairs to your canvas or covers are usually best left to a professional canvas repair shop. A good repair shop has the industrial-strength machines, materials, and experience needed to make these repairs cost-effectively for you. If you aren’t sure, call us and we can discuss it with you.

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