G'Day Dianna,
I looked up an old book Care and Repair of Sails, Jeremy Howard-Williams from Adlard Coles (how quaint, not using the internet).
Basically, Jeremy quotes from ICI chemicals in respect to Terylene but it is also applicable to Dacron.
Extract
Note that Alkalis can make the cloth more sensitive to UV light. Heavy stains need to be treated by specialist dry cleaners?
Many of the chemicals can be bought in a druggist( Chemist).
Avoid alkali based detergents on Terylene and Dacron if you can't rinse them out afterwards.
Detergent powders are frequently alkali based. Liquid detergents are less likey to have alkalis in them.
Large sails can be spread on a concrete apron and washed with hot water using bar soap or detergent. Any sail less then 150 sq ft could be immersed in a bath of 50 deg C and similarly treated. Do not rub away at any part for more than a quarter of minute.
If you cannot get rid of a patch of particularly heavy dirt you can soak the patch in straight detergent overnight.
If general soiling is still hard to remove soak in a solution of Sodium Metasilicate (WTF) and cold water,1 lb to a gallon. Do not allow the solution to come into contact with, galvanised luff wires, alloy slides, bronze thimbles, snap hooks or piston hanks.
As an alternative, you could put a solution of up to 6 oz of sodium hydroxide (Casutic Soda) into a bath full of water and soak it in that, don't increase the proportion. (Fancy a pomie knowing how to use a bath
).
Mildew,
Scrub with a stiff dry brush remove as much as possible, soak for a couple of hours in a cold solution of bleach (Sodium Hypochlorite) Domestos Brobat or Chlorox to ten parts water, a cup to half a gallon. Rinse afterwards and be prepared for only partial success.
Metalic stains
Stains caused by finely divided particles or rust and verdigris can be removed by the following 2 methods. Do not allow the solution to come into contact with gal wires, Iron, bronze and copper.
1 Immerse in a 5% solution of Oxalic acid, salts of lemon (WTF) dissolved in hot water. Hands and sails must be washed thoroughly as Oxalic acid is POISONOUS.
OR
2 Immerse the stained portion in a warm solution containing two parts concentrated Hydrochloric Acid per 100 parts water. Wash off thoroughly with fresh water.
End of extract.
It may be best to consult your local sail loft to find a better way. There is probably something on the market in a can.
I used the detergent on my genoa that was stained with the red dust from the 2009 dust storm and green moss and it didn't do much, but i used detergent and cold water on the lawn.
Hope it helps, take care.
Greg.