Rust converters?

[mickshep]

As we are nearing end of season my steel boat is looking pretty sharp apart from some slight rust staining along the wooden toerail base. Whilst restoring the boat in Holland we drew the line at removing the rails, leaving it as a winter job, What I envisage doing is removing the toerail, abrading back to bright metal (blasting not an option) then repainting. Has anyone any experience of the effectiveness of the "rust converters on the market as I'm thinking of coating the cleaned steel prior to painting in the hope of getting rid of even microscopic areas of corrosion so as to help delay/stop reoccurance, What do others think??? (Comments such as sell the bloody thing and buy plastic, will be treated with total contempt Sue)
Thanks in anticipation, Mike.

<hr width=100% size=1>"Naaa mate, she's made of tin"

 

[tcm]

erm in one part of the post your refer to the "wooden toerail", but then later to "rubbing it back to bright metal" - so it's not wood, right?

If there is rust staining, there but not elsewhere, i think it is because of the particular conditions there - perhaps the semi-seal allows salt etc to collect - so spacing with plastic washers would be an idea.

I have used the convertor products though mostly with mixed result - frexample all the cars i have ever used the stuff with have rusted to bits!

Seriouly, a rub back to bare metal and then primer, and then mount perhapsd with spacers so as to deter rust restarting should be a good inhibitor



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[mickshep]

Sorry. Should have made clearer. Plating of topsides carries on up to form a 4" upstand all around the deck then has a flat plate about 2" wide forming base for timber. Then capped with hardwood capping bedded on some compound and through bolted with wood plugs covering bolt heads, problem is moisture trapped between timber and steel, not a huge job at this early stage though not one I want to repeat every year hence my query. Prepped steel will get good paint system etc, but wondered about converter as "belt and braces" approach. Cheers Mike.

<hr width=100% size=1>"Naaa mate, she's made of tin"

 

[AndrewB]

They are not very effective. My experience of following the typical instructions, is that rust starts to bubbling up again within six - twelve months. Car bodies are a lot thinner than boats, and I suspect that at most they work effectively on just the very surface level of the steel.

Nevertheless I do use them as part of the process. Rust tends to drill into steel, and angle-grinding can be very wasteful of good metal if you try to remove all traces. After chipping and angle-grinding the worst, I power wire-brush and then paint on rust converter to deal with any trace remaining. A day later, wire brush again to remove the converter and loosened converted rust, and then start the priming process.

There are always some places that power tools won't reach (good steel yacht design minimises these). For those, chipping and rust conversion may the best that is possible short of blasting. I put on multiple coats of rust-converter over a period of weeks before painting with conventional (not epoxy) paints.

I have had better results with tannic acid (Fertan) rather than phosphoric acid based converters. But once rusts starts, it remains a constant problem.


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[iangrant]

The fisherman on the next pontoon uses brick cleaner - works a treat - it's like a commercial Y10 - takes all the rust streaks off all by itself!

Ian

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[Neraida]

If it's anything like Y10 it'll be brill.

<hr width=100% size=1><A target="_blank" HREF=http://www.quest-net.org/jamesaustin/images/Img1094.JPG> Recognise us? </A>

 

[Peter]

Try these web sites, used a product similar to the products in those web sites before on my steel boat. Going to try the “Navel steel” as detailed in in the 2nd site. It seems to work although cannot comment on long term protection. There advise on treatment is to remove the minimum loose rust to get approx. 10% bright metal, and then paint with treatment, then overcoat with primer. Where I can take back to bare metal, but in some areas there not a lot of room to get power tools in. In small, inaccessible areas use a Dremal.

Peter

http://mysite.freeserve.com/dgprotective

http://www.users.globalnet.co.uk/~dougadam/stelprod.htm




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[SlowlyButSurely]

Our steel boat has exactly the same arrangement as yours: bulwarks capped by a mahogany rail. Over the years I have tried everything to stop rust forming where the wood meets the steel and in the end I simply removed the wood and the problem was solved.

I have tried several different epoxies, conventional primer and paint, various rust converters including fertan and a revolutionary product that was much hyped about 10 years ago, the name of which I can't remember. In the long term I have found rust converters to be a waste of time. We have had our boat for 17 years so it's been long enough to see the results.

The best protection I have found is to prepare the steel with a wire brush in the angle grinder and apply 5 coats of International epoxy primer followed by three coats of gloss (or antifouling on the bottom). For really nasty areas use a sanding disc in the angle grinder. For areas you can't access with the angle grinder, scrape away as much rust as possible and seal it with a really thick coat of epoxy (and I mean THICK).

Best of luck!


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[vyv_cox]

Quite a few years ago now, (10?) some colleagues carried out controlled testing of every rust converter on the market, sponsored by one of our offshore oil companies. Their findings, based on exposure of laboratory-prepared panels at sea and in salt cabinets, was that none of them was effective. The optimum treatment found was grit blasting with aluminium oxide to SA 2.5 followed by epoxy coating with primer, undercoat and top coat. This remains the treatment for new and repair coatings for offshore installations and (I think) marine.

There may possibly have been some developments of rust converters since then that would give better results but I would not put money on it. The above treatment may be somewhat over the top for your application but it will give you some idea of what the professionals do.

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[summerwind]

I've only had my steel boat for a couple of years but where I have used rust converters, they have mostly worked. I've had the best results from the Hammerite products.

>I put on multiple coats of rust-converter over a period of weeks before painting with conventional (not epoxy) paints< The Hammerite product tells you to clear off all loose rust then paint with rust converter. When product has dried, (the metal turns a dark blue grey) immediately paint with primer. I have used the hammerite rust converting primer. I usualy put on a couple of coats. The paint is really thick so takes a while to dry. I then paint with top coats.

Despite what I was told in this forum, I painted my deck with single pot epoxy over the existing two pot. It has not peeled off and I only have rust problems where I have chipped the paint.

My hull is painted with chlorinated rubber paint. I'm not too happy with it because it remains quite soft. Where the boat is in contact with fenders, the paint lifts off onto the fender. Makes the hull look bloody awful and it is a constant job to keep painting over the area. Anyone have any better suggestions for hull paint - that I can apply over the chlorinated rubber?

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[MainlySteam]

And that remains the standard for new small steel vessels, both inside and out.

Yards will (should) repair by grinding back only to clean metal, then repeating the paint system. Sanding and wirebrushing do not give an acceptable binding surface. Rust convertors should not be considered.

We had an interesting experience with our own steel yacht which was built for us, and demonstrates the importance of the bare steel preparation. The bottom of the boat is fully faired (and I hasten to say it did not take much fairing) and after about 2 years in the water in a few areas the paint lost adhesion from the steel forming bubbles (not big just a few inches or so). What it was, when they were opened up, was that when they sanded the fairing back during the original process, in some places they sanded through to the steel which took the grit blasting bite off the surface, and that is where the coating later released.

John

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[Evadne]

We have tried several of the car-type brands on our mast step, which was once galvanised and painted white but is now white with rust streaks. None lasted a season. They seem to convert surface red rust to black oxide as advertised but this is not effectual at preventing new rust from forming underneath, even when primed and repainted. Sandblasting and re-galvanising is on the Round Tuit list (not really an option for you!)


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[Bladerunner]

Start with a zinc phosphate primer and coat with an epoxy ester paint.

<hr width=100% size=1> Bladerunner - Hung like Einstein. Brains like a donkey