How to Clean Sailcloth & Marine Canvas

There are a number of ways to clean sails and marine canvas. Some are more effective than others. Unfortunately, the most thorough methods also cause the most serious cloth breakdown, which leads to greater stretch and, thus, a poorly setting sail or sagging canvas. We can help you prevent damage while getting your marine fabrics clean.

All mechanical cleaning methods have the potential to cause cloth breakdown. Even large agitating tubs designed just for sails with carefully regulated water temperature will have the same effect on the sail as several weeks of hard use. And we definitely do not recommend using the machines at local laundromats to wash sails — they are never large enough and the water temperature is not carefully controlled. And of course, marine canvas isn't designed to be machine washed.

So, what's the best way to clean your sails and marine canvas items? Read on for proven, hands-on strategies to keep these fabrics clean and performing their best. We'll also recommend Sailrite^® products and household cleaners that effectively clean these fabrics.

Cleaning & Storing Sailcloth

Most sailmakers recommend frequent rinsing with fresh water. If that is not sufficient, spread the sail on a smooth, clean surface and brush it lightly with a mild detergent solution or with a specially prepared cleaner. But what if your sail is stained and rinsing doesn't do the trick? Never fear — many stains and spots can be removed from sailcloth. With just a little bit of time and a few materials, you can rid your sails of the following common stains.

Rust

Soak the affected area in a 5% solution of oxalic acid dissolved in hot water. Follow this with a 2% solution of hydrochloric acid in warm water. Finally, rinse the spot well with clear water.

Number Adhesive

Sailrite^® stocks 3M™ Specialty Adhesive Remover that works great. Or you could use Goo Gone^®, found in most hardware stores. Paint thinner and gasoline also work, although they will leave an oil stain in some cases. Do realize that two or three applications and some serious rubbing and scraping will be necessary no matter what you use.

Mildew

Iosso^® Mold & Mildew Stain Remover is made specifically to remove mold and mildew stains without damaging your sailcloth. You can also use 303^® Mold & Mildew Cleaner + Blocker. Soaking the affected area in a 1% solution of chlorine (household bleach will do) and cold water is another method. Finally, vinegar also serves to control mildew if used rather frequently, but it has limited use in correcting a problem that has gotten out of hand.

Oil, Tar & Varnish

The Iosso product mentioned above can get rid of oil and grease stains. You could also use trichloroethylene, either by itself or in solution with a liquid detergent.

Whenever confronted with a serious stain, do not expect complete removal. Usually the best you can expect is to lessen the discoloration. After cleaning the sail, dry it completely. Mildew will not grow on modern synthetic sailcloth, but it can grow on accumulated dirt if moisture is present. Although mildew will not harm the fabric, it will discolor or spot it.

Once the sail is dry, fold and store it in a cool, dry place. The method of folding that you select is not very important, but try to keep folds to a minimum. There are several schools of thought regarding how this can best be done — choose whichever seems most convincing to you.

Cleaning Marine Canvas

Next, we'll cover how to clean boat canvas. The acrylic canvas that is so often used for cover work is quite easy to clean. Here's a simple method for cleaning your canvas items.

Remove dirt, leaves and other large contaminants from the canvas. Spot-clean the canvas with a mild, natural soap in lukewarm water and a soft brush. Rub the solution into the stain from the outside in to avoid spreading the stain further. Rinse the canvas thoroughly with clean water to remove all soap. Air dry completely.

For stubborn stains or suntan lotion, use a fabric stain remover. Follow the directions on the container. Rinse the canvas thoroughly with clean water and air dry. And remember to never wash marine canvas in a washing machine.

Solution-dyed acrylic does not promote mildew growth. However, mildew may grow on dirt and other foreign substances that are not removed from the fabric. To prevent this, remove all foreign substances from the canvas regularly. To clean mildew stains, use 303^® Mold & Mildew Cleaner + Blocker.

You could also prepare a mild solution of one cup bleach (non-chlorine bleach is recommended) plus two capfuls of a natural soap per gallon of water. Spray this mixture on the entire affected area and allow it to soak in. If necessary, scrub vigorously with a sponge or clean rag. Sponge thoroughly with clean water, then air dry.

When boat canvas begins to leak, it can be coated with a silicone liquid. 303^® Fabric Guard will lengthen the original characteristics of the fabric if used right away. And, if used only when needed, it will restore the original fabric finish.

Conclusion

With regular maintenance, your sailcloth and marine canvas can stand the test of time and look great doing it. Please keep in mind that these are general cleaning and care guidelines. Marine canvas and sailcloth should always be cleaned in accordance with the manufacturer's instructions to best maintain their performance and characteristics. So, make sure to check the manufacturer's recommendations before you clean your sails and canvas items. Always read and follow the instructions and safety warnings on cleaning products as well.

We hope this blog answered all of your questions about manual sail care and boat canvas cleaning. Got a question we didn't cover? Reach out to our highly trained customer service staff via phone, email or the chat function on our website. We're ready to help you with all of your marine maintenance needs!

Footnote:

This blog is adapted from an excerpt from Jim Grant's Sail Repair Manual (#36302). It was revised and expanded in September 2023 to update the recommended cleaning products available at Sailrite.