Rust Stains & Rusting Fasteners

[kev_rm]

I'm sure this is a pretty basic question but I've got a few stainless fasteners and hardware that I have installed that are staining (rust colored) the surface they are mounted too and I also have a few screws in my railing/ladders that I did not install that are corroding. Is there a brand or alloy, or some mix of two I need to look for (or avoid) to prevent this?

 

[Coastal Cruiser]

Call these people, they will have the answer. Rust is what they do.


https://www.theruststore.com/

 

[what_barnacles]

Nice link. I ordered the small citrisurf SS kit. I have lots of screws that have rust stains, hope it works.

 

[Insequent]

I'm sure this is a pretty basic question but I've got a few stainless fasteners and hardware that I have installed that are staining (rust colored) the surface they are mounted too and I also have a few screws in my railing/ladders that I did not install that are corroding. Is there a brand or alloy, or some mix of two I need to look for (or avoid) to prevent this?

Firstly the link looks good. You need to firstly remove or convert the rust, then passivate the SS. This can be achieved by polishing or pickling. It is usually not a once-only task.

Secondly, you can minimise the issue by buying a better grade SS fastener. Cheaper ones will likely be 304 grade. Preferably use 316 grade SS. You can't tell the difference by sight. You need a reputable supplier, and will pay a little more, but should get an improved outcome. But you will still need to maintain as above.

 

[Xsbank]

The 316 hardware I use is labelled 316. Its the same stuff they use for pulp mills and other industrial processes. You pay more but its much better alloy for corrosive environments.

Also, enclosing stainless fasteners inside, say, wooden structures like decks will make it go black and bleed as soon as it gets wet.

 

[Xsbank]

The 316 hardware I use is labelled 316. Its the same stuff they use for pulp mills and other industrial processes. You pay more but its much better alloy for corrosive environments.

Also, enclosing stainless fasteners inside, say, wooden structures like decks will make it go black and bleed as soon as it gets wet.

 

[TwoDot]

I have had pretty good success using Starbrite Ultimate Fiberglass Stain Remover - Gel Formula. You need to spray it on and let it sit for about a half hour and then rinse it off.

 

[FF]

"Secondly, you can minimise the issue by buying a better grade SS fastener."

YES!

Purchase SS from boat places , not common hardware stores , or replace SS with Bronze.

 

[Wxx3]

This has also been a problem with me and stainless steel clamps.
Some are 304 vs 316.
I was able to separate them using a magnet. (316 SS has NO magnetism)

The screws in my rub rail caused a real mess.

 

[rwidman]

There is a product called "Spotless Stainless" https://spotlessstainless.com/ that will remove rust from stainless steel and the surrounding fiberglass.

It won't make cheap metal better but for items you can't easily replace, it works well and seems to prevent the problem from coming back.

 

[Taras]

Use " grampstrs pride" .
This stuff is awesome.
Just spray on and hose off.
Google it��

 

[DHeckrotte]

Barkeep's Friend: a cleanser with a bit of chemical oompf.

Even 316 Stainless will corrode/stain. Not nearly as often, though. Suspect areas are often at welds where the alloy is either less perfect or has changed a bit due to the heat. Also, areas where the Stainless has been scrubbed with iron-bearing grit, ground/cut with steel tools etc., will show corrosion.

 

[Martin J]

Sadly a lot of USA and Asian boats were produced with 304,306,308 stainless it was cheaper than using 316 European stainless. The only way you'll solve the problem is throw the old away and change to 316.

 

[Sea Q]

People don't realize if you have even good stainless and you us a regular screw driver on it that is "not plated" the steel in the bit will be the start of the rusting problem. Also be careful when anyone may be grinding metal around your boat the shaving and dust will start rusting on your stainless
There are lots of cleaners to do the job
Trick -- I coat the fittings with clear plastic spray paint after cleaning
This stops the air from starting the rusting again.

 

[CaptSteve53]

Just be be clear here when referring to 304 stainless steel, it contains chromium (min. 18%), and nickel (min. 8%). It is an austenite steel and is only slightly responsive to magnetic fields. It also contains 18 – 20% chromium and 8-10.50% nickel, and lesser quantities of some other elements.

Where as 316 grade stainless steel is a molybdenum-alloyed steel. The fact that it is also negligibly responsive to magnetic fields means that it can be used in applications where a non-magnetic metal is required. It also contains a number of other elements in varying concentrations, making it a preferable material for marine use,

What is see more often is Galvanic corrosion forming around two dissimilar materials such as SS with wood/rubber/Aluminium/steel/brass/bronze etc,
Strangely enough I find numerous boat owners that have never heard of Durolac as:

Duralac is an anti-corrosive jointing compound for use between joints of dissimilar metals. It is in the form of a tough, flexible, yellow paste with low moisture permeability, and contains barium chromate in an inert filler matrix. The barium chromate is only very slightly soluble in water, so it remains in the joint, even in the presence of a considerable flow of water. It has a long useful life because it only becomes active in the presence of conditions which promote corrosion.
• Indispensable for the effective sealing of joints between dissimilar metals --- even very active magnesium alloys
• Effective at preventing corrosion at stress contact points in similar metals, such as rivets in masts
• Protects metals in contact with non-metallic materials such as wood, resins, rubber, etc.
• Especially useful in saltwater environments which exacerbate corrosive processes

I have used this on mast fittings /rivets/bolts/wood and numerous other applications such as gaskets and even thread locking resulting even 10 years later there's no re action to dissimilar metal situations, I refer to it as a Zinc Anode paste and out performs(IMHO) other similar products such ac Tef Gel/Lano-tech etc.(Every boat owner should a tube in there tool box)-No i have no affiliation with them- just works !! end of story

Found here: https://www.fisheriessupply.com/saddington-consultants-plus-duralac-anti-corrosion-jointing-compound

Cheers Steve

 

[kev_rm]

Thank you all, very useful, as always this forum is a gold mine!