Which epoxy primer for keels?

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zeds

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I have decided to use Coppercoat and it is necessary to strip my keels, currently with one-pack treatments, back to bare metal which I am doing by hand. Which 2 pack epoxy primer would you recommend? Coppercoat suggest one called Hycote 152 - anybody familiar with it? Others seem to offer alternatives without explaining why eg International VC Tar2 and Interprotect. Ought I also to use a preservative before the epoxy and if so which and how many coats? Appreciate advice.
 
good question, I was about to post the same, I need to repair a small rust mark and need to grind it out to the bare metal.
 
Several comments.

Hand preparation cannot achieve the standard of preparation needed to justify the expense of applying Coppercoat. Angle grinding and other abrasive wheel methods simply drive the corrosion beneath the surface, where it will re-emerge and cause your expensive coating to flake off. The best answer is to grit blast the keel, followed immediately, i.e. within 30 minutes, by epoxy primer. This is a more expensive process, but then the Coppercoat is not cheap and you don't want it falling off within a couple of years. Treated in this way mine lasted 10 years. The Coppercoat was still working fine but the rust spread so much underneath that it would not remain on the keel.

I have used West epoxy as the primer coat(s). I don't know Hycote 152 but this link seems to imply that it is very similar to the West product. If Coppercoat recommend it I would go for that. This link suggests that manual preparation is OK but my experience is that blasting is far superior for long life. I would not put any other primer or product on, as there is a risk of introducing a layer with less adhesion than the epoxy. Five coats of primer are recommended, each coat applied before the previous one has cured. On a warm day it is possible to get all of this work done in daylight. Next the keel should be faired, again using West epoxy with microballons added for filler.

Finally, apply the Coppercoat. I did my keel for the second time at the beginning of last season and found it straightforward and successful. The Coppercoat DVD is very helpful.
 
I just had my keels blasted. Once blasted the guys used a rust inhibitor. Not sure what it is but it's turned the keels black. Now once we get some good weather, I need to epoxy. They use Hempadur epoxy from Hempel. Can't remember the number but there are 2 types depending on the temperature range. They use the lower temp range in this country.
 
If the keel is epoxied immediately after the grit blasting is completed, especially on a day with low humidity (if there is one in UK!) there is no need for anything else. One of the great advantages of using an epoxy is that its adhesion to the grit blasted surface is superb. Introducing a paint between the keel and epoxy introduces a weak bond which may negate the benefits of the epoxy. Five coats of epoxy will pretty much cover every pinhole and 'holiday', giving a barrier that is pretty much impervious to water.

So far as the product is concerned, it may be good and it may be used on the drilling rig that is shown. I do know that the biggest North Sea offshore production operator uses only epoxy primers and paints on all its rigs and platforms.
 
See this thread

I've not had the boat back in the water so can't comment on performance yet.

Hycote comes in some industrial containers and is messy stuff like any epoxy, I slapped on 4 coats on consecutive days with a brush, allowed to harden and then filled the holes using Hycote mixed with Microballoons. When the filling was done I sanded and applied another two lighter coats before flattening off and applying the Coppercoat.

Compared to applying Coppercoat outside in last year's 'Summer' Hycote was a doddle to work with.

This is the stuff AMC supply: Hycote 152LV
 
Many thanks, All, your comments much appreciated. AQ Marine advise me they supply Hycote 152 in 1 ltr packs - Googling it I had been unable to locate a lesser quantity than 5ltrs - so that one solved. Respect your comment, Vyv, re grit blasting but such a process is inappropriate at the moment for a variety of reasons and so I am going to risk manual preparation and await an auspicious weather window. Still unsure about an anti-rust treatment like Neutra Rust - Vyv fights shy of introducing anything which might interfere with adhesion which makes sound sense but do these treatments which cause a chemical change in oxidised material leave a barrier to bonding? Having an undue fondness for half-tide anchorages I accept that no treatment will survive long on the bottom 1" of the keels and would accept that just the keels may need treating within the "10 year life span" but this will be no more than I currently have to do annually. I also suspect the keels working in a seaway, changed stresses on taking the ground and expansion/contraction at the hull/keel join make it likely that small cracks may appear at this point and allow ingress of water and subsequent rusting and lifting of the Coppercoat. To just treat the keels after say 5 years seems acceptable. In this case, and given the price of the antifoul I generally use now (don't ask!!!!), the cost of Coppercoat does not seem unreasonable especially as they have an offer of £55 per unit for the duration of the Boat Show.
 
<< but do these treatments which cause a chemical change in oxidised material leave a barrier to bonding? >>>

I can't answer that within this context but I do remember that cars whose paintwork included a phosphate anti-rust treatment seemed to have a bond weakness there. If ever they were in shunts the paint sprang off, leaving the black/grey phosphate in evidence.

I understand about the manual proparation. If you can hire a needle gun that's the next best option after grit blasting. Also used on the aforementioned offshore platforms in areas where grit blasting is not applicable.
 
Both helpful comments, Viv - thanks. Certainly I am now much more aware of the implications of any choices I make. This has been a most valuable post for me - again thanks to all who contributed.
 
Just to place a full-stop on this particular thread. AQMarine have advised against the use of any anti-rust treatment which might introduce a barrier as Hycote already contains a fully compatible additive to perform this function. Thorough preparation is all that is required. I am sure Vyv is correct in that sand-blasting immediately followed by application of Hycote is to be preferred if at all possible.

Incidentally I have found Aquarious Marine Coatings(www.coppercoat.com)very helpful and efficient and a pleasure to deal with.
 
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