# Removing rust stains from "Starboard"



## TakeFive (Oct 22, 2009)

My C250's perch seats have some serious brown stains on them from crevice corrosion at stainless contact points. Now that the boat is out of a salt water environment, I would like to remove the rust stains. I've removed the rust from the stainless parts easily with oxalic acid and steel wool. However, the Starboard has been much tougher to clean. I tried the Whisk Rust Stain Remover (hydrofloric acid based) and it didn't touch it. I tried bleach and it didn't work either. I also tried some Soft Scrub, and it took some out but still a lot left.

Any suggestions of what would help remove it without damaging the plastic?

Once it's gone I plan to bed the seat material onto the stainless frame with non-adhesive caulk to fill the gaps and prevent water intrusion into the crevices. Any suggestions of what kind of caulk would be best. (I'm told not to use silicone caulk on plastic materials.)


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## sailingdog (Mar 19, 2006)

I really hope you didn't use steel wool on the stainless steel. Doing so pretty much guarantees that you'll have rust problems in the future. It embeds tiny steel particles in the stainless steel that become starting sites for future corrosion.

As for the plastic... did you try using MaryKate On-and-Off Gel? If that doesn't work, you can always try Spotless Stainless, which I reviewed not too long ago, and works pretty well at removing rust stains and cleaning up stainless steel.

If the area you want to bed the stainless is underneath the seats, you could always try butyl tape to seal/fill the space between the steel and the starboard. However, my suggestion would be to passivate the stainless steel and not use any sealant or caulk. Stainless steel corrodes far more readily if deprived of oxygen... Spotless Stainless is a treatment that is designed to passivate the surface of the stainless steel and help reduce future corrosion.

Here is a photo of the stainless steel swim ladder on my boat prior to applying and using *Spotless Stainless*.










Here is the same swim ladder after using Spotless Stainless once:










'Nuf said.


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## TakeFive (Oct 22, 2009)

Well, I did make some limited use of steel wool for a couple of really tough spots. What's done is done, but I can paint on some plastic stuff and peel it off to remove as many of the fragments as possible. I'll be sure to do that before I replace the seats.

I saw your review of spotless stainless but did not see anything about how it works on plastics. Acids work great on metal and ceramics because they dissolve a molecular layer, loosening the rust particles so they remove easily. Ditto for fiberglass - that's why oxalic acid is so good for removing discoloration. But this starboard plastic (which I think is HDPE) seems to be much more resistant to acid, so I am not confident that your Spotless Stainless would be successful. Have you tried it on stained starboard?

We have 80's temperatures coming this weekend, so I really want the seats to be installed by Saturday. No time to order anything online.


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## sailingdog (Mar 19, 2006)

I'll let you know, as I'll be treating the starboard stern rail seats from my boat later this month. 


RhythmDoctor said:


> Well, I did make some limited use of steel wool for a couple of really tough spots. What's done is done, but I can paint on some plastic stuff and peel it off to remove as many of the fragments as possible. I'll be sure to do that before I replace the seats.
> 
> I saw your review of spotless stainless but did not see anything about how it works on plastics. Acids work great on metal and ceramics because they dissolve a molecular layer, loosening the rust particles so they remove easily. Ditto for fiberglass - that's why oxalic acid is so good for removing discoloration. But this starboard plastic (which I think is HDPE) seems to be much more resistant to acid, so I am not confident that your Spotless Stainless would be successful. Have you tried it on stained starboard?
> 
> We have 80's temperatures coming this weekend, so I really want the seats to be installed by Saturday. No time to order anything online.


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## thekeip (Aug 8, 2007)

I would use the FSR product on plastic...including Dacron sails. Use the GEL, not the liquid Dab some on with a glue brush.
Howard Keiper


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## deniseO30 (Nov 27, 2006)

I just bought FSR it didnt' work on rust stains around the ladder flanges on the transom of my boat, CLR didn't work either. spotless stainless looks great for the metal ! I must get some.


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## TakeFive (Oct 22, 2009)

deniseO30 said:


> I just bought FSR it didnt' work on rust stains around the ladder flanges on the transom of my boat, CLR didn't work either...


It sounds like Denise already tried what some of you are suggesting, and it did not work.

So let me ask my question a different way. Who here has actually removed rust stains from starboard plastic, and what did you use?

My purpose of asking here is to get actual experience, not hypotheses of what might work. I have plenty of the latter already.


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## 14432 (Oct 24, 2006)

The Mr. Clean Magic Erasers work very well with stains on plastic and vinyl. I've used them for rust on HDPE with good results


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## svHyLyte (Nov 13, 2008)

We have a thick Starboard wear plate in front of our Windlass that the chain runs over as it is taken in or deployed and accordingly develops rust stains. I found that thoroughly saturating a paper towel with Wink Rust Stain Remover--a mild acid solution--and laying it over the stain will get most, but not all of the stain out. It seems that Starboard is more porus than one might expect and it takes a long while for the acid to gobble up the iron oxide. In no case use a bleaching agent--an Oxidizer--which will only exacerbate the staining.

FWIW...


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## k1vsk (Jul 16, 2001)

For about $4, you can buy a gal of muriatic acid (dilute) at any hardware or pool store which works far better than anything else suggested, doesn't damage anything and is very easy to use.

I've used it on SS, aluminum, gelcoat stains and starboard stains equally well. Just rinse off when you are done and wear latex or neoprene gloves.


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## MetalFinisher (May 14, 2010)

*Beware! Don't use muratic*



k1vsk said:


> For about $4, you can buy a gal of muriatic acid (dilute) at any hardware or pool store which works far better than anything else suggested, doesn't damage anything and is very easy to use.
> 
> I've used it on SS, aluminum, gelcoat stains and starboard stains equally well. Just rinse off when you are done and wear latex or neoprene gloves.


Muratic (hydrochloric acid) should not be used on stainless. It dissolves the passive chromium oxide layer that is integral to stainless' corrosion resistance and will end up corroding the s/s. Search any "chemical resistance of stainless" chart and you will see there is severe effect with even low concentrations of HCL. In a "salty" marine environment this is even worse because the chlorides in the salty air will begin to attack the surface before the CrO layer has time to autopassivate. Your part will fail prematurely. If you must clean rust in-situ, phosphoric/citric (better for environment) or nitric (not good for environment) formulations. Do not use muratic/HCL, You have been warned. I will post pics shortly.


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## MetalFinisher (May 14, 2010)

*Muratic Acid and s/s pictures*

This first picture shows an as original s/s bolt









#2 shows comparison of original bolt vs muratic acid submerged bolt (black)









#3 close up of submerged bolt with smut wiped off. Note:size reduction and rough surface finish.









#4 comparison of original bolt vs muratic submerged bolt. The submerged bolt was also subsequently electropolished for a corrosion correction study of HCL effected s/s. Note:size reduction of HCL'd bolt this is as result of surface dissolution by HCL on s/s.


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## k1vsk (Jul 16, 2001)

Dramatic pictures but there is no mention I noticed which describes the period of exposure. Are you implying these pictures reflect the process I described or are they the result of a prolonged "submerged" exposure?


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## MetalFinisher (May 14, 2010)

Exposure was un-agitated 15 minutes followed by 12 hours un-agitated. The most noticeable effect was in the first 15 minutes. While it is unlikely that you would wipe or be able to contact an in-situ boat part for 15 minutes. Make no mistake the passive layer is being removed and your just rolling the dice for future corrosion and part failure.


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## k1vsk (Jul 16, 2001)

That type exposure, as you describe, to produce those results is vastly different from simply and judiciously removing rust stains and flushing the residue with water but I can certainly agree that any prolonged exposure of ANY metal to acid can be detrimental.


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## L124C (Oct 4, 2007)

Since I didn't even know SS had a "passive chromium oxide layer", think I'm going to listen to the Metalfinisher!


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## Maine Sail (Jan 6, 2003)

L124C said:


> Since I didn't even know SS had a "passive chromium oxide layer", think I'm going to listen to the Metalfinisher!


Spotless Stainless works wonders!! It is citric based so falls into the _passivating_/safe for SS category not the _damaging_/unsafe for SS category when it comes to acids. Nitric and Citric are the two acids that can physically passivate or repassivate SS. You can't easily get nitric.....

No other acids should be used on SS other than Citric or Nitric, unless you want to risk permanent damage.

Muriatic/Hydrochloric, Oxalic etc. should NOT be used on SS.. MetalFinisher is spot on about this.....


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## copacabana (Oct 1, 2007)

What about phosphoric acid?


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## Brent Swain (Jan 16, 2012)

Muriatic acid removes rust from fibreglass instantly. Then splash water on immediately, to avoid staining.


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## rhr1956 (Dec 18, 2010)

I tried to clean up o length of chain by soaking in diluted muriatic acid. It turned the galvanized chain black in about 2 minutes. I worked for an hour trying to get the black off using soap and hot water and a scrub brush. Finally throug the chain in the trash and got a new one.


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