Hi I've had my boat for a little while now and I can't help but notice that there is a large probably 4ft long 1ft wide rust stain running through my sail. Now this isn't a new sail by any means but I would still like it to be all off-white and not part red. So any advice on how to clean this off without damaging the sail would be greatly appericiated. Thanks.
Get some oxalic acid (crystals) from a woodworkers supply shop. Make a strong solution (eg. 1/4 cup in a pint of water). Paint or dab it onto the rust stains and wait about 20 minutes. Then rinse well with water.
I must caution you when using any chemicals, that you should wear eye protection and disposable gloves. However, oxalic acid is rather safe to use; much unlike muriatic (hydrochloric) acid. FYI, it is actually the reducing agent property that does the job, not the acidic property. The iron in rust is in an oxidized form -- oxalic acid reacts with this to reduce it to a colorless substance. It doesn't actually remove the iron -- the rinsing does that!
hey tcwings20, you coould try some CLR (clacium-lime-rust remover) from the gocery store (houshold cleaning items).
I once used a spray bottle with diluted clorox to get some stains off a Hobie tramp- worked great. Just do it where there's
a hose (running water) close by- you don't want to leave the chemical on too long. If you see that the stain is not getting
lighter and cleaning off- spray the chemical off soon.
My biggest concern for this is that it won't hurt the sail. I'm sure if I left any chemical on there for a while it would hurt it but if I get the stuff off fast enough it won't make a difference right?
Oxalic acid would be much better than the phosphoric acid based rust removers. I have used oxalic acid on rust stains left on shower curtains -- the water-based acid contains no solvent that will dissolve dacron and/or plastic coatings. You really should test a very small corner first; just remember that it takes time (around 20 minutes to "clean" the rust stain), and then rinse with lots of clean water. I'd recommend doing this whole process on a concrete driveway with a hose.