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jonesthenuke

Maintenance of Epoxy coated hull

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5 years ago we had the boat shotblasted and coated with 2 pack epoxy. Its now time to get the boat out of the water for some general maintenance (anodes etc) and I want to repair some scrapes on the hull where the epoxy is damaged. The coating was Dacrylate Epidac 2 PE Pitch Epoxy. 

 

I have a little bit left in the original tin, as this was opened I do not want to use it after this time. I have looked to buy the same product but cannot see it on the Dacrylate website, and they have not responded to a request for a recommended replacement product.

 

Does anyone have advice what to use, and if so, where to buy it?  Thanks.

 

 

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Ask Sherwin Williams, Bolton. They are a worldwide coatings manufacturer and will be able to tell you what is compatible with the existing coating 01204 521771 

 

I would look at what you have left, it may well be perfectly usable, I keep my S-W hull paints for ever and they have always been fine after 10 years in the tin.

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A modern "surface tolerant" epoxy like Jotamastic 90 will almost certainly go over your existing coating with a bit of suitable preparation. check with the Jotun help line.

 

Take scrapes back to bare steel with a bit of roughness (NOT polished smooth). Rough up entire hull with a course sanding pad, then put a couple of new coats of epoxy on.   A good high pressure water jet will take off any bits of existing coating that are not well stuck on so what is left can be safely overcoated.

 

..............Dave

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What dmr said, but it will be easier to roughen up with a cup wire wheel in a big angle grinder.

Epidac 2 PE disappeared because it contained coal tar.  All use of coal tar is now effectively banned. The details are in a thread about tar varnish on here  somewhere.

N

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Latest from Jotun's UK distributor advising that Jotamastic is unsuitable. Have discussed over the phone they are adamant but I do not think they understand the difference between a coal tar epoxy and bitumen.  Now puzzled!

 

 

Does anyone have experience of overcoating a 2 pack Pitch Epoxy?

 

 

Text from SML Paints and Coatings:-

 

Thank you for your email. Jotun have sent through a copy of your enquiry.

 

We are Jotun’s main marine distributor in the UK so can help with your query.

 

As you already have a tar pitch product on the surface, you will need to apply a similar product over this. Pitch products are  very flexible so application of a two pack epoxy like Jotamastic 90 won’t work. There will be issues with adhesion and the paint system would crack and fail very quickly. The tar would also begin to bleed through the paint.

 

I recommend overcoating with Ballastic Black which is a traditional bitumen based hull blacking paint, similar to the Epidac. Chemically, adhesion between the two products won’t be an issue – a couple of coats will work well. The Ballastic can be applied directly on to bare metal, however, if the bare (i.e no trace of tar) patches are large, I would advise applying either a single pack primer such as Vinyguard or, if you can, a two pack like Jotamastic 90.

 

Two pack epoxies are very water resistant and durable with great corrosion protection for bare steel. They are becoming more popular with narrowboat owners, however, they are not flexible and don’t cope as well with the every day knocks and bangs associated with canal cruising. To change to a two pack system from a tar paint such as yours, the steel would need to be blasted completely back bare before starting again with e.g Jotamastic 90.

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I think they are talking bollox, which is odd as I bought my Jotamastc 87 from SML and they seemed to know what they were talking about. Maybe they have misunderstood? They don't seem to realise you've already changed to a two pack system. Also the bit about epoxies not being suitable for narrowboats is just nonsense. Jotamastic 87 or 90 is as flexible as you'd need it to be on a steel boat. Any hull paint will get scraped if you bash it into concrete, unfortunately there's no solution to that problem.

 

I would give Jotun a call and speak to their technical dept. 

 

Jotun Paints (Europe) Ltd. - Head office

Stather Road Flixborough, Scunthorpe North Lincolnshire DN15 8RR England

+44 1724 400 000

[email protected]
[email protected]

http://www.jotun.co.uk

Edited by blackrose

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I think we need Dr Bob here, but my understanding is that once an epoxy has set (the two parts reacted then that's it, its inert and resistant to most chemicals, so you can put anything over the top. I have overcoated epoxies (though not coal tar epoxies) with all sorts of stuff. Like Blackrose I think the person answering your question did not grasp that you were talking about an epoxy.

 

...........Dave

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I went through this process, with exactly the same epidac epoxy last year:

 

I applied Jotun 87 after a (very powerful) jetwash at Northwich dry dock and scratching up the original coating with a wire cup brush on an angle grinder. You may find, like me, very little comes off when its dry dock time. 

 

Bar the sections I've donated from to the network from the rubbing strakes, it appears to have held up well in the last 12 months. 

 

From memory, the main things I had to watch for were making sure I had enough time in dry dock for a full cure, getting the right mixing ratios (check the technical data sheet) and being quick enough to apply it within the 'pot life'. 

 

  • Greenie 1

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18 hours ago, Arf said:

 

I applied Jotun 87 after a (very powerful) jetwash at Northwich dry dock and scratching up the original coating with a wire cup brush on an angle grinder. You may find, like me, very little comes off when its dry dock time. 

 

Bar the sections I've donated from to the network from the rubbing strakes, it appears to have held up well in the last 12 months. 

 

From memory, the main things I had to watch for were making sure I had enough time in dry dock for a full cure, getting the right mixing ratios (check the technical data sheet) and being quick enough to apply it within the 'pot life'. 

 

Thanks. This is the kind of information which this forum is good at providing. Did you use winter grade hardener?

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18 hours ago, Arf said:

I went through this process, with exactly the same epidac epoxy last year:

 

I applied Jotun 87 after a (very powerful) jetwash at Northwich dry dock and scratching up the original coating with a wire cup brush on an angle grinder. You may find, like me, very little comes off when its dry dock time. 

 

Bar the sections I've donated from to the network from the rubbing strakes, it appears to have held up well in the last 12 months. 

 

From memory, the main things I had to watch for were making sure I had enough time in dry dock for a full cure, getting the right mixing ratios (check the technical data sheet) and being quick enough to apply it within the 'pot life'. 

 

Interesting that both you and BEngo suggest a wire cup brush, I feel that would be a bit too aggressive just for abrading the surface of the existing epoxy, I assume you did it with a very light touch, or did you use a brass brush?.

We did ours a couple of months ago and where the epoxy had scraped off I derusted the bare metal with a wire cup brush, and also feathered in the surrounding epoxy, and found the wire brush very easily took the epoxy right off back to bare steel. I did all the bare steel prep whist the boatyard did the epoxy abrading with some sort of pad in an angle grinder.

 

...............Dave

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I use a 6 in steel twist knot cup brush in a 9 inch Elu grinder.  Press just hard enough that the brush takes the weight of the grinder.  The epidac will go from that epoxy grey colour to a semi matt black with the odd swirl mark. Doing the bottom plate is really hard work so I use a smaller grinder.

 

There is no way I can get the epidac  off to bare steel with a wire brush though.

 

De rusting is a job for a grinder, backing pad and coarse grit fibre disc, or a coarse flap wheel. Even then, getting the feathering epoxy off is quite hard.

N

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On 03/08/2019 at 15:18, BEngo said:

I use a 6 in steel twist knot cup brush in a 9 inch Elu grinder.  Press just hard enough that the brush takes the weight of the grinder.  The epidac will go from that epoxy grey colour to a semi matt black with the odd swirl mark. Doing the bottom plate is really hard work so I use a smaller grinder.



There is no way I can get the epidac  off to bare steel with a wire brush though.

This is exactly what I've done both times. Maintaining that kind of pressure seems to have given it a decent key.

 

Might be that epoxies without coal tar are a bit less resilient to a wire cup brush. 

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On 03/08/2019 at 11:43, dmr said:

Interesting that both you and BEngo suggest a wire cup brush, I feel that would be a bit too aggressive just for abrading the surface of the existing epoxy, I assume you did it with a very light touch, or did you use a brass brush?.

We did ours a couple of months ago and where the epoxy had scraped off I derusted the bare metal with a wire cup brush, and also feathered in the surrounding epoxy, and found the wire brush very easily took the epoxy right off back to bare steel. I did all the bare steel prep whist the boatyard did the epoxy abrading with some sort of pad in an angle grinder.

 

...............Dave

Yes I agree. You only need to give the previously epoxied surface a key. I've just keyed 1 year old Jotamastic 87 on my stern deck with a palm sander and a 180 grit paper which was aggressive enough. 

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On 31/07/2019 at 18:50, jonesthenuke said:

5 years ago we had the boat shotblasted and coated with 2 pack epoxy. Its now time to get the boat out of the water for some general maintenance (anodes etc) and I want to repair some scrapes on the hull where the epoxy is damaged. The coating was Dacrylate Epidac 2 PE Pitch Epoxy. 

 

I have a little bit left in the original tin, as this was opened I do not want to use it after this time. I have looked to buy the same product but cannot see it on the Dacrylate website, and they have not responded to a request for a recommended replacement product.

 

Does anyone have advice what to use, and if so, where to buy it?  Thanks.

 

 

Hi jonesthenuke,

 

I work for Dacrylate.

 

The Pitch epoxy was withdrawn from the market when HSE legislation forced us to do so.

 

We would recommend the following for re-blacking the hull:

 

Clean the surface so that it is free of contamination.

If bare metal is exposed these should have any corrosion products removed and then spot primed with Epidac 2 HB Aluminium Epoxy.

Lightly abrade the whole hull

Coat in Epidac 2 HB Epoxy in Black, product reference is 90-294.

 

The Epidac 2 HB Epoxy 90-294 is designed to go over all existing coatings (except bitumen), even those of other manufacturers. It is surface and moisture tolerant and if the boat is re-floated a bit too quickly.... don't worry, it will continue to cure underwater.

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35 minutes ago, Dacrylate Paints Ltd said:

Hi jonesthenuke,

 

I work for Dacrylate.

 

The Pitch epoxy was withdrawn from the market when HSE legislation forced us to do so.

 

We would recommend the following for re-blacking the hull:

 

Clean the surface so that it is free of contamination.

If bare metal is exposed these should have any corrosion products removed and then spot primed with Epidac 2 HB Aluminium Epoxy.

Lightly abrade the whole hull

Coat in Epidac 2 HB Epoxy in Black, product reference is 90-294.

 

The Epidac 2 HB Epoxy 90-294 is designed to go over all existing coatings (except bitumen), even those of other manufacturers. It is surface and moisture tolerant and if the boat is re-floated a bit too quickly.... don't worry, it will continue to cure underwater.

OK that sounds like a solution, thanks for posting the advice. Can you advise where I can buy these products?

I have looked on the Dacrylate website and can only find a light grey Epidac 2, and cannot find 90-294. Can you advise?

 

 

Edited by jonesthenuke
Second line added following web search.

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I have always bought epidac products direct from dacrylate distributors.  They have these in various places  which were listed on their website. They take plastic, and deliver if their nearest branch is not handy for collection.

 

N

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On 20/08/2019 at 14:13, jonesthenuke said:

OK that sounds like a solution, thanks for posting the advice. Can you advise where I can buy these products?

I have looked on the Dacrylate website and can only find a light grey Epidac 2, and cannot find 90-294. Can you advise?

 

 

Hi jonesthenuke,

 

The 90-294 is not on our website, in fact, a lot of our products aren't and we will be relaunching our website later in the year, although I still doubt that all of our products will be listed on the website.

 

You can purchase this product from myself or I can point you towards a distributor who will need to buy it in from us.  I'll send you a private message with my contact details on.

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