Water proof levels of canvas?

[Jack Long]

Is Sunbrella waterproof? Are all marine canvases not?

As mentioned in another thread I put the bimini up today- used a tarp since I only ordered the sewing machine yesterday and the Sunbrella today...

Anyway, the tarp ends about halfway over the dodger which is made of some unknown canvas type. It seeps. An hour or so of light rain and I've got stead drippage coming through. It looked to be in solid shape- not threadbare- no holes...

[imagine2frolic]

It's cloth, and cloth will weep no matter how tight the weave. Get some waterproofing spray...............i2f

[GordMay]

After removing & cleaning the “canvas, you should use spay-on that contains a fluoropolymer formula to waterproof the fabric.
Do not use a waterproofing treatment that contains silicone
Spray the product on the canvas evenly and let it dry. Re-spray in a cross-hatch pattern (@ 90 degrees), let dry, and re-install.

Cotton-based canvas actually has some natural waterproofing, in that the fibres swell up, closing the weave, when wet - something akin to the planking on a wooden boat.

See also Sunbrella care instructions:
http://www.sunbrella.com/na/en/downl...MarineTops.pdf