Coating bare steel with antifouling paint

See this datasheet. Rustoleum have written to me to confirm (THREE TIMES!) that this antifouling paint can be applied to bare steel. I repeat, BARE STEEL. The instructions simply say "Remove all loose rust or deteriorated coatings by scraping or wire brush."

http://www.rustoleumibg.com/images/tds/CBG_Anit_FoulingPaint.pdf

Ray

 

PRODUCT DESCRIPTION

Rust-Oleum Marine Coatings 1 qt. Flat Black Bottom Antifouling Paint provides a handsome and practical solution to prevent the buildup of marine growth below the waterline. This paint releases copper and can be applied to fiberglass, wood or steel surfaces in fresh or saltwater situations. This paint can be applied over hard antifouling coats but soft antifouling coats should be removed.


For use below the waterline in fresh or saltwater environments
Flat finish offers a subtle appearance
Cover up to 85 sq. ft. for ideal use
Can be applied over hard antifouling coats but not soft antifouling coats
Apply to wood, steel, fiberglass and any non-aluminum trailer boat
Releases copper to prevent the buildup of barnacles, algae and other marine growth in mild to moderate fouling conditions
Subject to or will include a recycling fee in the following states: CA, OR
Actual paint colors may vary from on-screen and printer representations
MFG Brand Name : Rust-Oleum
MFG Model # : 182821
MFG Part # : 182821
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SPECIFICATIONS

Application Method Spray, Roller or Brush Assembled Depth (in.) 8 in
Assembled Height (in.) 8 in Assembled Width (in.) 8 in
Color Black Color Family Blacks
Container Size 1 QT-Quart Coverage Area (sq. ft.) 85 ft²
Exterior Paint & Stains Product Type Pool Paint Low Temperature No
Manufacturer Warranty Satisfaction Guaranteed Number of coats recommended 2
Paint Base Epoxy Paint Product Type Exterior Paint/Stain
Paint Type Epoxy Pool Paint Base Epoxy
Primer Required No Returnable 90-Day
Sheen Flat/Matte Skid Resistant No
Surface Use Yes Time before recoating (hours) 4
UV Resistant Yes Water Compatibility

 

anti fouling coatings

excellent info!! does anyone know what products to use on bare aluminium hull below water line?

 

Ray
I wouldn't use it direct on steel, copper and steel is not a good mix? a good barrier coat first to isolate

 

While Rustoleum certainly has plenty of experience coating steel, this just sounds wrong.

Copper and steel are both conductive, and salt water is an excellent electrolyte. What your describe sounds like it would make enough electricity to run your boat. There must be a reason all the other paint manufacturers recommend a barrier coat on steel before using a copper based paint.

Ask Rustoleum if they will cover the cost of re-plating your boat below the waterline when electrolysis eats it until its as thin as tin foil. I'll bet their warranty is for replacement of defective materials only and they assume no liability for other damages.

Steve

 

does anyone know what products to use on bare aluminium hull below water line?

I use Altex/Devoe whatever they call themselves today, excellent products for protective coatings and antifouls.

http://www.altexboatpaint.com/

 

BUT - - an analogy is that just a few years ago a doctor eradicated stomach ulcers overnight by prescribing a strong antibiotic, something nobody before ever tried.

Could Rustoleum have discovered that this simply works? The paint is an epoxy-based copper anti-fouling. They actually went out of the way - and IN WRITING - to me to say that primer is not required.

I may actually go with this advice, and just monitor the bottom frequently, as an experiment - and if it doesn't work, I have a strong case that Rustoleum must cover the cost of re-coating with an alternative, because of their advice.

 

Hope you're right Ray
I perceive a bit different from the can label



http://www.rustoleum.com/cbgimages/documents/MA_QT_BoatBottom_07.pdf

 

Good call Tazman, from the label:

STEEL HULLS, UNDERWATER METAL PARTS, LEAD KEELS: Contact
Rust-Oleum Technical Services for complete priming instructions

Rust-Oleum shall not under any circumstances be liable for incidental or consequential damages. By purchase or use of this product, buyer agrees that the sole and exclusive remedy, if any, is limited to the refund of the purchase price or replacement of the product at Rust-Oleum’s option.


Yes, I know they told you in writing you don't need a primer. Use at your own risk.

And I got a kick out of "Cuprous Oxide 45.7%" being called "heavily loaded with cuprous oxide"

Steve

 

Ray

There are standards for paints. There's no way this type of antifouling can properly protect your hull. Looking at the MDSS for the product it's just a run of the mill single pot antifouling formulation. I't not a fancy new product and in the paint matrix any Rosin slowly dissolves releasing fresh copper toxin.

Sure it will stick to bare steel but it's most likely that they mean small patches of broken down coating. I suspect whoever is contact you is themselves a bit confused about required practice.

You would be remiss not to coat the steel first, and get several good coats of 2 pack, say a polyamide cured salt water immersable epoxy to around 200 microns ( at least 150) . Then apply the antifouling.

There is no such thing as a free lunch.

 

Never heard of rustoleum antifoul.

Locally The Budget conscious bare boat charter fleets use mid range Jotun antifoul. Good paint. Apply it over properly primed surface. Purchase it in 20 litre bucket.

 

The 'Rust-oleum' product contains copper as an oxide, so it does not conduct and there is no risk of electrolysis. That is the good news!

The bad news is that almost 50% of the "paint" is not epoxy but a metallic oxide that slowly dissolves in seawater. Over time, that leaves you with a coating full of holes, exposing bare steel to the environment.

Guess what happens......

 

NO. Galvanic corrosion.

http://geminimarinesurvey.com/yahoo_site_admin/assets/docs/Marine_Metal_Corrosion.325111027.pdf

Yes. The paint should corrode before the hull .... But, that is up to you.

And free advice is good for what you paid for it - I don't think they would cover your experimental use of their product.

 

From your pdf:

"suitable for all Non-Aluminum trailered boats."

I think that means do NOT get the boat wet.



Sounds like better than average anti-fouling paint? But, it admits in the directions it has limits.

 

A bit of a laugh, huh? Rustoleum actually got back to me and retracted the advice! They are a good bunch and make great paints, we use Rustoleum here with great results all over the boat. In fact, for the price here we couldn't beat Rustoleum's antifouling paint so will be using it - but for the antifouling coat above steel primer and paint!
Cheers, Captain Ray