I have removed my furling Genoa for cleaning, it has spots of mould on the sail and between the sewn seams. I have been advised to only use soapy water and a brush, no chemicals, but this does not work. I have also tried a diluted mix of vinegar and soapy water, still does not work. I have read online that soaking in a mixture of bleach and water rids the sail of mould. It is a heavy dacron matt.
Any ideas on what works best?

Good articles here you have probably seen;

stingysailor.com/2018/10/13/sail-restoration/

www.northsails.com/sailing/en/2018/04/mildew-on-sails-what-to-do

www.cruisersforum.com/forums/f55/sail-washing-20281.html

I've had good mildew and dirt removing results on dacron jibs and mains from a hot water and Domestos mix - probably 1 cup of Domestos in 10l bucket. Sponge it on, leave for a few hours, hose and sponge off. But reading the above links makes me wonder if I have damaged any stitching................Domestos is mainly sodium hypochlorite so it could be ok as per the North article. The stitching presumably is polyester (dacron) so might be ok.

en.wikipedia.org/wiki/Domestos

Maybe I should have used this stuff.

www.theboatwarehouse.com.au/boat-building-maintenance/cleaning-polishing/starbrite-sail-canvas-cleaner-473ml/?gclid=EAIaIQobChMI2ZaI-JDY8wIVvxitBh0ueAXMEAQYASABEgK8PvD_BwE

The suggestions above are all good for removing mold from the surface of the sail, but the mold in the seam (it's actually in the double sided tape used to glue the seams) will be nearly impossible to get out and using strong enough chemicals could very possibly damage the hold the glue still has on the sailcloth in the seams. It's like when the mold gets inside the laminate of a taffeta laminated sailcloth, it ain't coming out without damaging the sail.

Good old exposure to sunlight and UV will do better than increasingly harsher chemicals...

Edit: from 35 years in the sailmaking industry.

Have heard good reports from a local sailmaker and online reviews about wet and forget, takes time to work

www.wetandforget.com.au/

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cammd said..
Have heard good reports from a local sailmaker and online reviews about wet and forget, takes time to work

www.wetandforget.com.au/

en.wikipedia.org/wiki/Benzalkonium_chloride

Interesting stuff and I might give it a go. I have not had much joy with any of the products. I use a soft broom and Truck wash and agree with Jethrow's comments the best method is to just go sailing.

Oil of Cloves

www.biome.com.au/blog/6-things-to-know-about-using-clove-oil-for-mould-removal/

Shannon Lush, swears by a simple mixture of a 1/4 teaspoon of clove oil (don't use more - its very powerful) to 1 liter of water as a mold killer and remover.

Thanks for all of the suggestions and links, I had a look through all of them. I might try soaking overnight to see if that helps. The biggest problem as mentioned, is the mould in the seams. In the future, I will make sure that I air the sails more often. Cheers, Terry

With the 30 year old sails that came with my boat four years ago what I did was
get some nappiesan ,hose down sail, rub nappiesan on the mould with soft broom, fill a clean sulo ( rubbish bin) put sail in ,liberally put nappysan over sail then fill with water.
Leave for a day in the sun agitating with a broom or whatever every few hours .
Next day empty out the now black water refill with fresh , agitate then hang out sail , I have tall side fences so hung it there, washed down with hose. Mould disappeared but rust spots remained . Then I bought new sails .

Sodium percarbonate is the active in nappysan, get it from your brew shop cheap as chips, won't do any harm may or maynot remove the stain your concerned with, but the rest of the sail will be impressive, needs to be soaked . I recently tried the borax/ bicarb /TSP ( pink bottle wash from the brew shop ) combo on old school life jackets, improved them heaps but not 100%

Chuck all the sails in a swimming pool overnight!!

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Jethrow said..

Edit: from 35 years in the sailmaking industry.

That can't be right, we're about the same age and I'm only 25......

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Bananabender said..
With the 30 year old sails that came with my boat four years ago what I did was....... bought new sails .

Ya. I'm totally obsessed with keeping most of my good sails in perfect condition (never folded, only rolled around PVC tubes, hoisted straight from the PVC tubes without ever allowing a single crease to form, never flogged, etc etc) but once mould gets in there's not really any way back, as Jethrow says from his many years of experience.

The sail cleaning people at Brookvale have an awesome system if you give up on home remedies
they use a vacuum flask system that draws the dirt and mould out of the fibres.

Just to follow up, I ended up soaking my sails overnight in a solution of sodium percarbonate as suggested above. The sails are a lot cleaner but the mould stains are still there. I'm drying them in the sun now which seems to be helping to bleach them out a bit more. Thanks again for all of the replies and suggestions. As mentioned by the experienced sailmaker above, the best solution is to air them out more often as not a lot can be done once the mould gets into the seams. Cheers, Terry

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Stockie said..
The sail cleaning people at Brookvale have an awesome system if you give up on home remedies
they use a vacuum flask system that draws the dirt and mould out of the fibres.

+1 for Vacuwash at Brookvale.
I had my 8yo mainsail done, im pretty sure it had never been off the boom with the PO. Works out about $10 per sqM + gst. Brilliant job and worth every cent IMO. Left some small rust stains, but mould 98% (or better in some areas) gone.
(I have no affiliation, but very pleased with the result)
edit- i did try most of the diy methods above, but the difference after the pro job was quite noticeable.