Hammerite

[capt_courageous]

Hi
Has anyone tried using Hammerite paint on iron keels. I know the stuff works on gates etc. but are there any problems using it on keels. For example does antifouling stick to it.
Thanks

 

[sailorman]

Hi
Has anyone tried using Hammerite paint on iron keels. I know the stuff works on gates etc. but are there any problems using it on keels. For example does antifouling stick to it.
Thanks

primocon would be better

 

[Skysail]

Hammerite (or even Hammerite + Primocon) works OK in my experience but there are conflicting opinions:

http://www.ybw.com/forums/showthread.php?t=181206

 

[ghostlymoron]

Hammerite No.1 Rust Beater

I used this on my keels last year followed by anti-fouling. After a year there is a lot of rust re-appeared so it was not a success. Also the hammerite was not compatible with the anti-fouling and bled through. This was probably from overcoating too soon.
I'm going to try something different this year! The ultimate solution is grit blasting followed by a suitable primer but that's beyond my pocket so I'll probably use some kind of rust passivator followed by Primocon. It all depends on sub-strate preparation though and wire brushing is not enough. I did consider using a needle gun but couldn't hire one locally.

 

[rivonia]

I used this on my keels last year followed by anti-fouling. After a year there is a lot of rust re-appeared so it was not a success. Also the hammerite was not compatible with the anti-fouling and bled through. This was probably from overcoating too soon.
I'm going to try something different this year! The ultimate solution is grit blasting followed by a suitable primer but that's beyond my pocket so I'll probably use some kind of rust passivator followed by Primocon. It all depends on sub-strate preparation though and wire brushing is not enough. I did consider using a needle gun but couldn't hire one locally.

Did you try a big wire brush attachment for you electric drill? it is a much cheaper option.

Peter

 

[BGW]

Did you try a big wire brush attachment for you electric drill? it is a much cheaper option.

Peter

You need to be careful using this option as it can 'polish' the surface making it difficult for paint to stick.

 

[vyv_cox]

Unfortunately both wire brushes and abrasive discs tend to drive rust into the surface of cast iron, where it soon reappears when immersed again. A needle gun is a better option, used on offshore platforms (at least, the ones I know) where grit blasting cannot be used.

A colleague tested rust passivators in controlled trials a few years ago. None of them was justifiably effective. The paint system adopted for oil platform use was grit blasting followed by epoxy primer and epoxy top coat. AFAIR the total number of coats was five or six.

 

[MM5AHO]

Hammerite has an undeserved reputation for being something magical.
Its paint. That all.
All paints are porous. (Quote from Paint research association) Its the degree of porosity that counts.
Paint is only a barrier to keep oxygen from the iron and so prevent rust formation. As soon as the barrier is perforated, or water borne oxygen gets through, rust starts. And as rust expands in volume terms from what the original iron volume was, it causes the paint to fail even faster. (blisters)

So a coating system that contains mica flakes (or similar) will be far less porous, and so resistant to ingress. And a paint system that it chemically resistant to the sea, and UV stable, thats what you need. If you then introduce some zinc or other sacrificial metal, then you'll get barrier plus cathodic protection.

Typically the most effective paint systems are just that - a system. Not a single coating, but a system of various coats doing different jobs.

And all that depends on a clean substrate. Painting over rust only means faster rust re-formation.

Zinga is a zinc rich paint that works well. If ovecoated with perhaps a 2 pack epoxy, and on a properly prepared surface, you'll have a good chance.

 

[KREW2]

primocon would be better

+1, after a good scrape and rub down, leave for a day then, then brush Fertan on any rust patches, finish with a patch coat, followed by a top coat of primocon. This works well for me.

 

[johnalison]

I'm surprised at the trouble people have had with Hammerite. I used it on my previous boat - Sadler 29 - and it worked a treat. I used to just wire-brush by hand after chipping the rough stuff with an old screwdriver, use any old Hammerite, and primocon over it before antifouling. I use to get a lot of rust spots but they seldom returned after my treatment, over about ten years.

 

[dt4134]

+1, after a good scrape and rub down, leave for a day then, then brush Fertan on any rust patches, finish with a patch coat, followed by a top coat of primocon. This works well for me.

Iron absorbs moisture from the atmosphere very quickly & very effectively. Leaving it bare for a day is not a good idea. Better to cover it as quickly as possible.

 

[Pasarell]

Cast Iron Keels

I have spent most of my working life on / under ships, rigs bridges etc specifying paint schemes and supervising their application.

Best methods of preparation are: -
1. Dry abrasive blast
2. Hydroblast
3. Needle gun
4. Grinder
20. Wire brush (the jump to 20 is not a mistake!)

There are recognised standards for preparation using these systems for steel but cast iron is rather more complicated due to porosity and material quality. For cast iron the best you can do is remove all previous coatings and all existing corrosion. The reason wire brushing is virtually useless is because it polishes rust beautifully - gets it nice and shiny - but does not remove it.
You also need to remove all traces of salt - difficult because of the porosity of cast iron - but if you don't it will promote corrosion no matter what else you achieve.
This means that, in an ideal world, you wash, blast, wash, blast. Proper hydroblasting is excellent for this but unlikely to be practical or economic on a small boat (hydroblasting = >35K psi).
The best you are likely to achieve with cast iron is an even, matt, light grey colour over the whole surface.
Do not apply rust converters!
As soon as possible after preparation apply the first coat of anticorrosive and work it well into all the pits and voids on the surface. 100% coverage is far more important than getting rid of brush marks! For this job rollers are completely useless.

Hammerite is a reasonable anticorrosive but is not really suitable for permanent immersion. Putting Hammerite on and then overcoating with Primocon is pointless. Stick with 1 sort of anticorrosive but put several coats on.
As already stated, all paint is porous. Epoxy resin is one of the least porous types. So are moisture cured urethanes.
An additive in the paint can help it to be less porous - MIO (micaceous iron oxide) is one of the best.
Best anticorrosive (as opposed to waterproof) contains zinc as well as this will inhibit corrosion on the inevitable surface defects on cast iron.
Primocon is a good conventional primer that is surface tolerant to poor preparation. If you are preparing the surface well it is worth investing in a good quality priming system that will last much longer.
Whatever priming system you use, put plenty on as per manufacturers instructions (paint is porous but more paint is less porous!) With a brush you put on about 50 microns at best, less on edges, and most anticorrosive schemes need at least 250 microns

There - got it off my chest!

 

[Hardley]

Painted my keel with Hammerite 5 years ago, every year I put a new coat of anti fouling over it, not had any problems at all and the original rust patches have not reappeared, so I am happy with Hammerite.

 

[pappaecho]

Zinc rich " cold galvanising" worked well for me

 

[Seanick]

I have spent most of my working life on / under ships, rigs bridges etc specifying paint schemes and supervising their application.

Best methods of preparation are: -
1. Dry abrasive blast
2. Hydroblast
3. Needle gun
4. Grinder
20. Wire brush (the jump to 20 is not a mistake!)

There are recognised standards for preparation using these systems for steel but cast iron is rather more complicated due to porosity and material quality. For cast iron the best you can do is remove all previous coatings and all existing corrosion. The reason wire brushing is virtually useless is because it polishes rust beautifully - gets it nice and shiny - but does not remove it.
You also need to remove all traces of salt - difficult because of the porosity of cast iron - but if you don't it will promote corrosion no matter what else you achieve.
This means that, in an ideal world, you wash, blast, wash, blast. Proper hydroblasting is excellent for this but unlikely to be practical or economic on a small boat (hydroblasting = >35K psi).
The best you are likely to achieve with cast iron is an even, matt, light grey colour over the whole surface.
Do not apply rust converters!
As soon as possible after preparation apply the first coat of anticorrosive and work it well into all the pits and voids on the surface. 100% coverage is far more important than getting rid of brush marks! For this job rollers are completely useless.

Hammerite is a reasonable anticorrosive but is not really suitable for permanent immersion. Putting Hammerite on and then overcoating with Primocon is pointless. Stick with 1 sort of anticorrosive but put several coats on.
As already stated, all paint is porous. Epoxy resin is one of the least porous types. So are moisture cured urethanes.
An additive in the paint can help it to be less porous - MIO (micaceous iron oxide) is one of the best.
Best anticorrosive (as opposed to waterproof) contains zinc as well as this will inhibit corrosion on the inevitable surface defects on cast iron.
Primocon is a good conventional primer that is surface tolerant to poor preparation. If you are preparing the surface well it is worth investing in a good quality priming system that will last much longer.
Whatever priming system you use, put plenty on as per manufacturers instructions (paint is porous but more paint is less porous!) With a brush you put on about 50 microns at best, less on edges, and most anticorrosive schemes need at least 250 microns

There - got it off my chest!

Absolutley!! Someone who knows what they are talking about, rather than enthusiastic DIYer.

We prep as above,then coat with Bradite surface tolerant Primer, then Micaceos (sp) iron oxide, followed by 2 pack poly or antifoul primer.
Bradite is available from Brewers outlets. It comes in 5l tins only so club together with your mates for the coatings and a group blasting.

Google for the above products!

 

[johnalison]

I don't think that any of us would deny that good preparation from the start is always going to be the best solution, but for many of us that degree of meticulousness is not an option as we only have the odd weekend in March when it isn't snowing. Hammerite can be a good bodge, and I used primocon as well to ensure good adhesion with the antifoul rather than to improve rust-prevention. I'm sure there are plenty of other solutions, but the answer to the OP is - yes, sometimes.

 

[Searush]

Word of warning. I hired a needle gun last year to do my cast iron keels. It cost about 50 squid for the day & knocked loads of rust off, but was damned hard work & in places broke through into small bubbles or voids in the keel, so I had to apply filler before painting. I used primocon followed by a proprietary "red lead" that was clearly red, but almost certainly NOT lead! The result has been good, but not perfect. I probably wouldn't bother again.

Hammerite is cellulose based, that may be the cause of incompatability with many antifoul paints.

 

[DownWest]

One thing I found out about Hammerite is though it touch dries fairly quickly, the final drying is something like a week or three. This might explain the bleeding through. I sprayed some gates with it, 20% (or 30%?)dilute as instructions and over coat within an hour or leave it for a week. Something to do with the skin forming between coats and preventing the under layers from gassing off. ( this was a few years ago, so my memory is a bit iffy on it)
Andrew

Second Nick on the post from Pasarell. Real info

 

[rudolph_hart]

I eventually got fed up with the annual patching of the rusty bits on the wing keel of my Dehler 35, so last winter I did it properly, using Jotun zinc-based 2-pack epoxy primer, which is designed to deal with minimal surface preparation.

Process was follows:

1. angle grinder with disk (used loads of disks)
2. angle grinder with wire brush
3. Rust converter (Kurust etc)
4. Jotun aluminium epoxy primer, thinned with epoxy thinners
5. Wash, using green 'brillo' pad
6. Fair with more Jotun epoxy
7. Wash, light sand
8. Antifoul primer (2 coats)
9 Antifoul

The Jotun stuff I got from Shepherd Marine. It's so thick you can briefly invert the opened tin and it won't spill. Even when mixed with curing agent it's still thick enough to to be difficult to apply with a paint brush. Hence the thinners

So far, it's working well - no rust patches this year on haul-out.

I hope this helps

 

[Heckler]

Hi
Has anyone tried using Hammerite paint on iron keels. I know the stuff works on gates etc. but are there any problems using it on keels. For example does antifouling stick to it.
Thanks

My ex Bene 351 had a cast keel, looks as if Bene used to cover with gel coat as a protector, when I had it the keel was covered with rust blisters. I Got a small angle grinder, ground back to bare metal, put hammerite primer, then hammerite smooth on top then antifoul. Worked a treat. By the way, cast iron is a funny material, if you get rust on it its not like steel, it doesnt seem to get any worse, so really I wouldnt be too arsed about getting a perfect repair!!
Stu