When my Caledonia yawl was not yet a year old, I took my son and my father out sailing from the marina in Edmonds, Washington. Once we cleared the breakwater, the breeze filled the big lug main and we took off, leaving a fizzing white wake astern. As usual, I started out beating to weather so our homeward leg would be an easy downwind run. The wind picked up on our way south and was soon more than I could handle. I sheeted the mizzen in tight to heave to so I could lower the main and tie a reef in. The big sail was rather unruly and in my struggle to get it lowered I barked three knuckles on my right hand. With each handful of sail that I grabbed, I left splotches of bright red blood.

I remember the outing well because I see those stains every time I set sail in the yawl. They’ve been there for about 15 years despite the countless times I’ve hosed the main with fresh water to wash salt spray away.

Parts of that sail and some of my other sails are speckled black with mildew, probably from keeping them for years in an unheated garage made humid by a leak in the roof. I’ve read that mildew doesn’t damage the Dacron fibers that my sails are woven from, but it looks terrible. Bleach is a common household remedy for mildew and mold, but while Dacron can tolerate it, nylon can’t, and to be on the safe side with the materials used in thread, boltropes, and whatever else is part of a sail, it’s best to avoid bleach.  To see if I could get my sails looking better, I tried Shurhold’s Moldaway, a “powdered oxygenated cleaner” that does not contain bleach or chlorine—right on the label—lists sails among the items it can clean.

Photographs by the author

The Moldaway powder is dissolved in a measured amount of warm water and then brushed, sponged, or sprayed on the fabric to be cleaned. The fabric can also be soaked in the solution.

For spot-cleaning jobs I followed the instructions and mixed 2 tablespoons of powder to a quart of warm water and stirred until the powder was all in solution. It can be applied with a brush or a sponge or sprayed on, then sponged or brushed lightly. I opted to put  a couple of quarts of solution in a plastic tub and one by one immersed stained parts of a few sails. If Moldaway would do all the work without my having to lift a finger, I’d be all for it.

I treated one of the blood stains on the yawl’s mainsail and areas of mildew in that sail and others. When in contact with the sailcloth, the Moldaway solution effervesces with very small bubbles, the sort that Fizzies flavored-drink tablets of my childhood did. I let the “scrubbing bubbles” scrub for 10 or 15 minutes. When I pulled each section of sailcloth out of the solution and rinsed it with fresh water, I was pleased to see the mildew and blood stains gone. What really surprised me was how clean the sail’s zigzag stitching was: it had gone from an ashy gray to sugar white. And all of the cleaning had happened without the wear and tear that scrubbing could have imposed on the sail.

The now-brown blood stains have been on this sail for years and remained after the many times the sail had been rinsed with fresh water. (Safety pins mark the spot to be cleaned. The gray splotches are just spots wet with fresh water.)


The blood stains disappeared after soaking in Moldaway without any scrubbing.


This Dacron sail has been speckled with mildew.


Moldaway proved effective in removing mildew.


I don’t know what caused this rust stain, but tested Moldaway on it even though the product is meant to remove only stains made by organic matter. I stitched thread around the area to mark it.


Moldaway did make good progress with the rust stain (with some scrubbing). What impressed me most about this test was how clean the stitching at right turned out.


The stain on my cotton family flag has bothered me for years. It may have been caused by pine tar. I tried to remove it with Moldaway, but without success. The Moldaway did not cause the sewn-on black and dark-blue fabrics to fade or bleed.

Eager to see what else Moldaway could do, I dipped my kayak’s nylon-fabric-covered foam seat in the solution and the treated section came out with all the grey and speckles gone. The smallest sail I have, a nylon sail for my kayak, went for a soak in Moldaway, and although it has faded a lot by exposure to sunlight, it came out gleaming with the remaining color restored to brilliance.

My Caledonia sail is already looking much better with the worst of its stains gone, but I’ll miss the marks my knuckles left, not only for the memory of sailing with my son and father, but also for the reminder to reef early.

Christopher Cunningham is the editor of Small Boats Magazine.

Moldaway is available from Shurhold. A 12-oz jar costs $16.48. It is available at many retail outlets.

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