Rust preventative spray

[trailertrawlerkismet]

Looking for your thoughts on the rusting stainless hardware on the underside of our swim platform. After 6 total months in salt water the swim platform hardware seems to have more rust stains then normal. I’ve cleaned it all up but want to try and prevent the rust from coming back so quickly. I found an aerosol spray that claims to be a rust preventative for metal/stainless subject to salt water/water exposure. Cosmoline RP 342 Heavy Formula, which is sprayed on is advertised to last up to 3 years. So has anyone used this product or another they are happy with or any other ideas?

Jim F

 

[TugSully]

Cosmoline is what the military packs weapons in for long term storage to prevent rust. Not fun stuff to remove from a rifle/handgun packed in that stuff. I don't know how it would work in your situation but I might be concerned about its "ECO Friendliness" in the water. It is a petroleum based product. Constant oil slick??

 

[trailertrawlerkismet]

Thanks for the information. I see that CRC also makes an aerosol product but I’ll need to research the eco friendliness. The RP342 product info did state when sprayed on it dries but I did not read anything about eco information, I’ll research further. Good point.

Jim F

 

[captstu]

I use T-9 Boeshield, developed to reduce corrosion after a Boeing 737 lost a roof panel and a flight attendant blew out. It has kept the rust under control quite well, but I can't imagine it working where salt water was blasting on the surface, such as under the swim platform.

You might try passivating the stainless - I use ZUD - it works quite well and lasts a few months. There is really no solution to lower quality stainless mixed with high quality stainless - dissimilar metal corrosion.

"Stainless steel is not resistant to chemical or physical attack. The corrosion resistance of stainless steel depends on the formation of a 'passive surface film' composed of nickel and chromium oxides (Cr203 & Ni0). Passivation involves removing free Fe or 'tramp Fe' from the stainless steel surface." There are a variety of products you can use. Zud removes the rust and starts the process, old time chemical photographers used potassium permanganate and Nitric acid to passivate new developing tanks - the process was miserable but kept the tanks clean for years.

 

[NorthernFocus]

The only real way to stop it is to replace all of the fasteners with 316ss. Test the fasteners with a magnet and replace any of them that are even mildly magnetic. Don't buy ss fasteners from a typical hardware store as it will almost surely be 304ss. And if you're buying from a marine store it's not a bad idea to carry a pocket magnet along with you. Historically all of the stuff I've bought from West Marine has been 316. But I haven't purchased any fasteners for quite a while due to having substantial inventory collected over the years.

 

[trailertrawlerkismet]

Thanks for the additional info, I checked the CRC information and it has an aquatic warning, so this is a no go. I like the idea of checking the washers to see about there magnetism, as this is where all of the rust is showing up. The problem is that the rust seems to migrate therefore replacing washers with 316 material, if indeed they are not 316, will prevent this from reaccuring.

Jim