303 Fabric Guard protects Sunbrella and other fabrics from UV damage -- fading and disintegrating -- and restores water repellency.

303 Fabric Guard

Sunbrella is expensive. Having someone else sew things out of Sunbrella makes it even more expensive. And by its very nature, Sunbrella is out in the sun all the time, protecting your other stuff from UV damage. (NOTE: see my post on 303 Aerospace Protectant for a sister product to protect hard surfaces such as dinghies, jerry cans, fenders and more.)

But how do you protect your Sunbrella (or other canvas)? Getting a few extra years of life out of your covers can save some serious money!

303 Fabric Guard protects Sunbrella and other fabrics from UV damage -- fading and disintegrating -- and restores water repellancy.303 Fabric Guard is the answer. It both protects fabric from UV damage — fading and disintegrating — and restores water repellancy. It’s also supposed to repel dirt, but I have never done side-by-side comparisons to see if it really does.

  • The company says it lasts “up to three years” — we reapplied it every year in tropical climates. The sun is intense there and so are the rains!
  • Reapply before you notice a lack of water repellancy for the best protection.
  • Use it even if (or maybe especially if) your canvas is brand new. The earlier you start using it, the more it will protect.
  • Nothing is going to make your canvas totally waterproof in tropical monsoon conditions, nor make it last forever. 303 Fabric Guard helps but cannot perform miracles!
  • Coverage . . . with “professional grade equipment” the company says that 16 ounces will cover up to 100 square feet. For most of us in the real world, it’s more like 50 square feet using either the trigger spray bottle or a tank sprayer (more on this below); a gallon realistically covers about 400 square feet. Two light coats are recommended, so that means that one gallon will do two coats on about 200 square feet.
  • Some people advocate using a paint brush and brushing it over the dodger and bimini, which get the most sun and rain. We never tried it (usually those who did it were trying to get an extra year of waterproof-ness as they weren’t near a place to get new canvas made), but if you do, coverage will be far less than spraying.
  • Drying time depends on how heavy a coat you apply and how humid it is out. In the Sea of Cortez in the middle of summer, it could take less than an hour. In high humidity areas, such as the middle of the summer in the Midwest, two to three days wasn’t unusual — making it hard to pick a window without rain in the forecast.
  • Don’t spray on a windy day.
  • Sunbrella, Practical Sailor and Sailrite all recommend it as well. There are cheaper brands but our experience is that they don’t work nearly as well (we’ve been using various “water repellant” sprays on small boat covers for 40+ years, and this really is superior).

Tons of places sell the 303 Fabric Guard. In my experience, it’s extremely expensive at marine stores — right now, a gallon at West Marine is almost double the Amazon price. Most big box and home improvement stores only sell the 16- and 32-ounce spray bottles, which aren’t going to go very far on most boats. How much you’ll need depends a lot on your boat — don’t forget things like cockpit cushions, canvas sidewalls, hatch, winch and jerry can covers, fender covers and so on.  If you have chaps on your dinghy, be sure to do them. It took close to two gallons to do Que Tal‘s canvas; I’m guessing it’ll be less than one for Barefoot Gal.

Buy from Amazon (note: can only be shipped to the contiguous 48 states and comes by ground):

303 Fabric Guard protects Sunbrella and other fabrics from UV damage -- fading and disintegrating -- and restores water repellancy.

If you buy the 303 Fabric Guard in gallon containers (way cheaper per ounce), you’ll have to get/repurpose some sort of a sprayer as the gallons don’t come with a sprayer. If you have just a few things to spray, the trigger bottles are okay. For larger surfaces or more items, your hand will thank you for getting a small tank sprayer, such as the one shown at right.

This one is available on Amazon (click here to see/buy). It holds a liter (quart) so it’s a manageable weight, you pump it up, then press and hold the trigger to spray (there’s a trigger lock for doing really large areas). While you can usually get larger tank sprayers at home improvement and discount stores, I’ve never seen one that small that’s a pump up type — they’ve all been squeeze triggers.

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  • Lysa Evans
    Posted at 28 July 2014 Reply

    There is a company called Nikwax that makes excellent waterproofing materials.

  • Becky Croston
    Posted at 28 July 2014 Reply

    I have used 303 for years on our canvas dodger and now on our new boat. It must be put on clean canvas or it will take a pressure washer to get the “sealed ” stains out later (inherited with our new boat.) Worth the expense for sure in water “proofing ” and extending the life of the canvas.

  • Jim Allen
    Posted at 28 July 2014 Reply

    Rust-Oleum also has “Never Wet”

  • CherylAnn Falconer
    Posted at 28 July 2014 Reply

    Thank for sharing, Just scrubbed our dodger & need to do this asap.

  • Marie H
    Posted at 28 July 2014 Reply

    We used a cheaper sealer a couple years ago. We didn’t realize there was a difference in products. By the end of last summer we were convinced that we needed a new bimini on our Carver. It was leaking so bad at the seams and elsewhere that we thought for sure that new canvas was the only way to go. Well, this spring we decided to put 303 on to try to get us to fall and new canvas. We washed the bimini really well; let it air dry and then sprayed on the 303 pretty heavily. We put it back up wet to make it a little easier and hoped for the best.

    Well, we don’t need new canvas! We have been through several heavy rains and this stuff WORKS! We are absolutely amazed how well. I highly recommend it!

  • Chris&Janet
    Posted at 30 July 2014 Reply

    We find it goes on better and lasts longer using a four inch roller. Less over-spray as well.

  • Rick Belew
    Posted at 01 August 2014 Reply

    I have been using this stuff for 10 + years two coats ever year and water does not penetrate. You can find it in camping area and shoe dept. my sunbrella is 10 years old and still look good. It takes four cans at about $6 per can

  • Charlotte Caldwell
    Posted at 25 September 2017 Reply

    I love the way that water just pools up once the fabric has been treated with 303.

  • Cathy Coyne Wehle
    Posted at 25 September 2017 Reply

    Got it on the new covers I made 🙂 Love it

  • Susan Kam
    Posted at 25 September 2017 Reply


  • Beth Joyal
    Posted at 25 September 2017 Reply


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