Please, please do not use oven cleaner on sails! It may be used on some hard surfaces to remore grease and possibly mildew, but any sailmaker would gleefully be rubbing his hands at the thought of the business generated by the inevitable destruction sails.
Most modern sythetic materials used in sail production are very easily damaged by strong acids or alkalis. If you do not believe me, try a test on a pair of tights (old!!).
Speak to your sailmaker about cleaning sails or look it up.
I agree ... Oven Cleaner is an agressive cleaner, based on acid compounds.
I use B&Q Mould remover spray, designed for Tents, awnings and general canvas work.
My sprayhood and mainsail cover were terrible last year with green algae and mould along all edges etc. I took 'em off, sprayed them down, scrubbed with a small brush lightly, hosed off and BOY what a difference .... only thing was I then could see the old frayed stitching !!! BUt they looked like new, the colour came up, algae . mould disappeared and the bottle syas that it protects after cleaning ... so lets see what happens !