Firstly, let me say great thread, thanks boatin for kicking it off.
Today was getting rid of the rust stains of my stainless steel rudder stock. Prior to this, it had been untouched for 2-3 years, so it looked pretty awful. It had that tea-stain look all over the stainless, and I initially attempted to clean it by:
1) Warm water and mild detergent. Fail.
2) White vinegar. Fail
So I did a bit more research and took a punt on Septone Rust Converter (phosphoric acid), mainly as Supercheap was open and had it on the shelf.
I applied it with a soft paint brush, left for 15 mins, then wiped it off with a damp rag, then wiped it over with metho on a rag. Did this half a dozen times, and amazingly it worked very well.
It is not perfect yet, but I wish I had of taken a before shot, it is amazing the difference it made.
While I as waiting , I sanded back the wooden tiller and started applying some marine varnish. I thought the end product was pretty good, that is till I saw what Southace is doing !!!

SB