I'm probably posting something that most everyone already knows but I thought I would give my two cents worth.

If you don't want to read the rest. Just use Whink and follow the instructions on the label.

My sails had several deep rust stains on various panels. Nothing to bad at a distance but enough to bother a guy with OCD.

I decided to look up as much advice as I could find regarding rust removal from Dacron and other synthetic fabrics. I found a huge variety of info and advice with several products mentioned. I tried three very carefully and in relatively inconspicuous locations. I even asked the wife for ideas as she's a chemist.

Oxalic Acid (Bar Keepers Fried)(Rust Aid) works well on gelcoat and stainless fixtures. Due to it's light acidic properties with didn't seem to break down the rust in fabric. I will keep a can of Bar Keepers Friend for hull work.

Hydrochloric Acid or Muriatic Acid just stinks to high heaven and burns on skin contact. It reacts corrosively with most metals including stainless steel. This is nasty stuff and requires a 2% dilution. I'll stick to concrete cleaning for this stuff.

Hydrofluoric Acid (Whink) is the best overall rust stain remover for fabric. This stuff worked perfectly. The key to success is time and patience. I wet down the areas to be treated and applied the Whink directly. I made sure the area didn't dry during treatment. Depending on the severity of the stain it removed all the rust quickly. Once again patience and don't let it dry. When the rust was gone I washed the area with mild liquid detergent and plenty of water.

As with all chemicals proper safety should be taken. Reference the MSDS for these products. Dacron can easily be damaged by these products with over exposure. I don't recommend doing any sail cleaning in direct sunlight and besure to rinse before and wash after. Whink and Bar Keepers Friend are both available at Wal-Mart.

Good luck

I trust you gave CLR a try... not being a chemist... I do not know the active compound in it. Also, The Works kicks rust pretty quick.

I use both of them to clean out my well point's settling tank. We have a lot of rust in the water here in Florida, the settling tank gets caked, especially in the wind and water level. Both these products takes the tank's interior back to a lovely white.. but then again... it is jell coat.

In another forum, a lady suggested the used of Qxy Clean to remove dyed on graphics that suck. Still have not tried that.

CLR didn't work for me. It contains phosphoric and glycolic acid and didn't cut through the deep rust.

When I bought my H16 the hulls were very oxidized. They look liked they had been painted with flat paint. I couldn't wait to go sailing so I put it in and had a blast. I sailed it in north Escambia Bay which has a lot of tanic acid. Tanic icid is the dark brown stuff in mostly fresh water that is created by decomposing organic materials. Driftwood is a common cause.

Anyway, when I got home the hulls looked like they had been sitting in a bath of coffee. Tanin stains are difficult to remove if you don't know what you're doing. I heard about FSR and gave it a shot. Wow! FSR is great for organic stains.

Now the hulls are reconditioned and buffed back to a shine and no more tanin problems.