Getting rid of rust stain

[Lepke]

I've painted a lot of steel vessels, including USN. The pictures look to me like the steel wasn't moisture free and the coating was too thin.
When you prepare steel by sanding, the surface isn't smooth. There are small pits below the sanding level. The pits have rust and the rust holds moisture. If you can't sand blast or high pressure blast, you need to etch the steel with a product that dissolves the rust. I etch even blasted steel.
Then an epoxy primer of 2 or more coats depending on the thickness and 2 coats of finish. Lightly sanded between coats. If sanding breaks the coating, then another coat in that area. I did mostly commercial vessels and rollered the paint because it's easier to put down a thicker coat, no over spray, etc. A good bare steel painting should last 10 years with touch up. Even then, just the areas of broken coating were taken to bare metal. The rest sanded and re-top coated. Today there are newer and better coatings than I ever used - I have a wood boat now.

[Deltasailor]

Originally Posted by andy marsh

A friend once told us an acount of her going into IGR chandlers in Nidri Greece.
This is was when Danny was still with us, sadly he has passed away now.
She said to Danny i have a problem?
Danny said fire away!! she said how can i remove stains from my knickers. 😨
he laughed. 😄

It turned out she had a Bavaria and her clean nickers had layed against the steel coated screws in the over head lockers that had started to rust.

He handed her some oxalic acid that did the trick.

So lesson to all Bavaria owners. Dont put your white panties in the over head lockers or they may get stained. 😉 and yes oxalic acid will remove rust stains from your knickers.

Reading this reminded me when after the Vleho storm I talked to Danny, I said " I was reading Miles Smeeton Twice is Enough about his capsize off South America" It was all your fault he retorted!!!

[suenodelmar]

A simple, inexpensive source of oxalic acid already diluted and ready to use:

"The Works" brand of "Tub and Shower Cleaner"

This product dissolves rust and also is an excellent wood bleach. Just brush it on right out of the bottle, let it sit for a few minutes, and then wash it off with fresh water.

In the United States, this product is available in the homecare and cleaning products section of grocery stores. In discount stores such as Dollar Tree, a bottle cost only $1. We keep several bottles aboard our boat.

[jamhass]

The issue here isn't just a rust stain, such as on fiberglass boats.

Issue is more that rust is bleeding through cracks in the paint.

Oxalyic acid will work for a very temporary cosmetic fix, but to do a longer-term fix will require (at least): a down-to-bare-steel refinish of the affected area.

Phosphoric acid (and some proprietary formulations) may offer a slightly longer-term impact since phosphoric acid converts rust to a phosphate, which lends some self-protection to further rusting. This is the active ingredient in metal preps used on bare steel before priming.

[Djarraluda]

I believe just about everyone here has missed the point.
It was the Targa he ground back, but the rust is on the deck.
I would suspect, the rust on deck is the bare ferrous particles that blew there, so they are surface spots, not penetrating rust.
As such, cleaning the stain is temporary if the particles are in the deck paint now. It will need some reciting to protect.
Sadly, it needs the oxalic acid then repaint - just keep the particles off the targa !!
Roger

[Uncle Bob]

Originally Posted by Djarraluda

I believe just about everyone here has missed the point.
It was the Targa he ground back, but the rust is on the deck.
I would suspect, the rust on deck is the bare ferrous particles that blew there, so they are surface spots, not penetrating rust.
As such, cleaning the stain is temporary if the particles are in the deck paint now. It will need some reciting to protect.
Sadly, it needs the oxalic acid then repaint - just keep the particles off the targa !!
Roger

+1. Odd how many missed the entire point.

[Paul Elliott]

My initial reply was assuming that the metal particles had fallen on the painted surface but had not adhered or penetrated the paint. I've gotten steel filings on my gelcoat, and I didn't notice until they started rusting. I washed off the loose particles, then treated the stains with oxalic acid. This worked well and was permanent except for a few spots where I hadn't removed all the particles.

[newhaul]

Originally Posted by suenodelmar

A simple, inexpensive source of oxalic acid already diluted and ready to use:

"The Works" brand of "Tub and Shower Cleaner"

This product dissolves rust and also is an excellent wood bleach. Just brush it on right out of the bottle, let it sit for a few minutes, and then wash it off with fresh water.

In the United States, this product is available in the homecare and cleaning products section of grocery stores. In discount stores such as Dollar Tree, a bottle cost only $1. We keep several bottles aboard our boat.

I took it that he noticed the rust spotting on the paint the next day after he did the grinding on the targa.
So a simple oxcalic scrub and rince should be enough.

[Boatwayupnorth]

Djarraluda and Newhaul got it right. As I wrote, I was grinding away on the targa and the wind blew the grinding dust all over the starboard side of the boat. The rust stain is just on the surface of the old paint; not on a newly painted one.
So, oxalic acid it is! I have ordered the magical stuff from ebay yesterday and will report back how it worked.
Thank's for the input, everybody!
Walter

[CCR2580]

"FSR" works really well. Just a apply with a a toothbrush rub and and let it set then rinse with water.

[Dougtiff]

Year's ago, while living in Singapore, a Steel yacht sailed in from australia, having been built there by the owner captain, the boat had no rust, unusual for a steel boat, i ask the owner how he kept it so rust free, the answer was a miniature sand blaster, consisted of a paint sprayer, with a pipe replacing the nozzle,some clean dry beach sand, a short hose attached to a SCUBA tank via a gas welding regulator, all very simple, sand blast the problem and coat with epoxy, overcoat with your paint of choice, now one can just go and purchase a miniature sand blaster and hook it up to air.

[Bleemus]

Forgive my ignorance but what is a Targa?

[NSboatman]

OSPHO. great stuff. cleans rust stains beautifully- just remember to rinse very well with lots of fresh water.

Also, if you're doing any kind of grinding, then you're spraying little bits of metal that will flash rust everywhere... which of course you've discovered. I've used a leaf blower to good effect here, as well as shop vacs, and the best of all is an enclosed grinding head with high-capacity vacuum on it. Doing it anywhere near anyone else's boat is going to require extreme care and cleanup... as I've also discovered to my dismay. paying to get other people's boats either cleaned up or painted is really frustrating!

[Boatwayupnorth]

Originally Posted by Bleemus

Forgive my ignorance but what is a Targa?

It is
A) something I thought I could translate directly from Norwegian and German into English
B) the handy part aft where solar panels, radar, windgenerator and whatnot is attached.

Originally Posted by Bleemus

Forgive my ignorance but what is a Targa?

[Boatwayupnorth]

Originally Posted by Bleemus

Forgive my ignorance but what is a Targa?

It is
a) something I thought I could export directly from Norwegian and German into English
b) the handy metal arch aft where solar panels, radar, wind gen and whatnot are attached. [emoji6]