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barmyfluid

Epoxy over bitumen

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I'd decided to give SML's new ballastic epoxy over bitumen a try for my boat this time round:

 

https://www.smlmarinepaints.co.uk/primers/two-pack/Ballastic_Epoxy

 

I've just booked her in and was chatting about ordering blacking and I mentioned this - they reckoned that they usually used Jotun 87 and did so over bitumen?!

 

Possibly a misunderstanding somewhere, but anyone had experience of using either over (well prepared) bitumen?

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2 minutes ago, barmyfluid said:

I'd decided to give SML's new ballastic epoxy over bitumen a try for my boat this time round:

 

https://www.smlmarinepaints.co.uk/primers/two-pack/Ballastic_Epoxy

 

I've just booked her in and was chatting about ordering blacking and I mentioned this - they reckoned that they usually used Jotun 87 and did so over bitumen?!

 

Possibly a misunderstanding somewhere, but anyone had experience of using either over (well prepared) bitumen?

Does Epoxy 'stick' onto anything else ?

 

When doing my boat the epoxy instructions were "LOUD AND CLEAR"

 

ALL PREVIOUS COSTINGS MUST BE REMOVED DOWN TO BARE SUBSTRATE.

 

If you don't then it reacts and blisters. You can put a 'single pack' over cured Epoxy, but not the other way around.

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2 minutes ago, Alan de Enfield said:

When doing my boat the epoxy instructions were "LOUD AND CLEAR"

 

Well, the instructions with the newer stuff are loud and clear that it's allegedly fine over a variety of coatings so long as they're well prepared, but AFAIK Jotun 87 is bare metal only going by the book. However, I've learned that by the book doesn't always reflect on reality, especially in the marine world.

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The epoxy is only going to be as good as what is under it. So I see no advantage, you still have blacking on the hull and it will still come off just as easy when you hit something.  So  you are going to have explain to me the advantage?

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2 minutes ago, Kudzucraft said:

The epoxy is only going to be as good as what is under it. So I see no advantage, you still have blacking on the hull and it will still come off just as easy when you hit something.  So  you are going to have explain to me the advantage?

Not having it trashed by the first fuel spill I go through?

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33 minutes ago, barmyfluid said:

Well, the instructions with the newer stuff are loud and clear that it's allegedly fine over a variety of coatings so long as they're well prepared, but AFAIK Jotun 87 is bare metal only going by the book. However, I've learned that by the book doesn't always reflect on reality, especially in the marine world.

I agree that is what the data sheet said, so if it does start to blister than you might get the supplier to pay for it to be re-done.

 

I missed one or two bits of 'old' paint and now I have got a few 'air-bubble' type blisters that you can pop.

Its going to have to come off and be rubbed down properly this time before re-painting.

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I had this done last year, the water line looks good so far, whether I do the same next time depends what it looks like in dock after pressure washing. I was very much in two minds about it, it may or maynot work. I will give an honest report with photos at the next docking. I don't think it can be less effective than bitumen but we will see. I may have wasted a couple of hundred quid, who knows. I had it done a Northwich Dry Dock and they do the base plate as well.

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My boat was bitumened after resteeling and then at it's reblacking the yard two packed it. Not all the bitumen was knocked off and the 2 pack hasn't lasted well, and I presume will do better next time.

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3 minutes ago, ditchcrawler said:

I had this done last year, the water line looks good so far, whether I do the same next time depends what it looks like in dock after pressure washing. I was very much in two minds about it, it may or maynot work. I will give an honest report with photos at the next docking. I don't think it can be less effective than bitumen but we will see. I may have wasted a couple of hundred quid, who knows. I had it done a Northwich Dry Dock and they do the base plate as well.

Cheers for the report. I think if the waterline looks ok after a year it's a good sign, and the resistance to fuel has got to be worth the cost, even if overall it's not as tough as a shotblast job. TBH I think any coating + prep will lose the argument between a 15 ton boat and approaching bridge hole. 

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41 minutes ago, Arthur Marshall said:

My boat was bitumened after resteeling and then at it's reblacking the yard two packed it. Not all the bitumen was knocked off and the 2 pack hasn't lasted well, and I presume will do better next time.

Was it just 'standard' 2 pack then, as that's what the yard said they used over bitumen? Do you think it's performed better or worse than straight bitumen at the waterline? 

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Listen to the advice above. You're wasting your money putting Jotamastic 87 over bitumen. 

 

I've used Jotamastic 87 extensively when I worked in a boat yeard and I've also got 4 coats on my widebeam. It's a great product but you need to follow the technical data sheets to the letter.

 

https://www.jotun.com/Datasheets/Download?url=%2fAG%2fAG__515__Jotamastic+87__Euk__GB.pdf

 

https://www.jotun.com/us/en/b2b/paintsandcoatings/products/Jotamastic-87.aspx

 

Edited by blackrose
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1 hour ago, barmyfluid said:

Well, the instructions with the newer stuff are loud and clear that it's allegedly fine over a variety of coatings so long as they're well prepared, but AFAIK Jotun 87 is bare metal only going by the book. However, I've learned that by the book doesn't always reflect on reality, especially in the marine world.

 

Well, in this case Jotun know exactly what they're talking about.

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2 minutes ago, blackrose said:

 

Well, in this case Jotun know exactly what they're talking about.

Yeah, I think there were crossed wires with the yard on this one but it was worth asking about. I'm also hoping SML know what they're talking about with Ballastic Epoxy, as it's such a new product it's hard to find real world reports on performance. Being such a big hitter in the marine coatings world you'd think they wouldn't put out something that performed poorly when used as recommended.

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4 hours ago, barmyfluid said:

Not having it trashed by the first fuel spill I go through?

That makes sense.

 

But I am asking here to try to understand.  The epoxy is not going have a any grip on the hull, just the blacking. So when you scrap the side your still going to scrap the epoxy and blacking off.  So now you still have a small area of blacking exposed to fuel spills of what ever.   I can't image fuel spill happen that often either. 

 

Just seems to me unless you apply the epoxy to the hull so  you have good adhesion that you are really gaining a lot for the money it costs?  Again, just trying to wrap my head around why you would do this.

Edited by Kudzucraft
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11 minutes ago, Kudzucraft said:

That makes sense.

 

But I am asking here to try to understand.  The epoxy is not going have a any grip on the hull, just the blacking. So when you scrap the side your still going to scrap the epoxy and blacking off.  So now you still have a small area of blacking exposed to fuel spills of what ever.   I can't image fuel spill happen that often either. 

 

Just seems to me unless you apply the epoxy to the hull so  you have good adhesion that you are really gaining a lot for the money it costs?  Again, just trying to wrap my head around why you would do this.

I get surrounded by fuel spills all the time - most are from bilge pumps and leaky engines.

 

Well, the product I'm planning on using is specifically for use over 'aged' existing coatings, bitumen being one. The recommended prep is pressure washing, degreasing and giving any gloss a key with sanding. At the end of this, whatever is left on there will have a reasonable amount of adhesion, and one of the features of the new epoxy is a level of flexibility, which I guess gives it more of a sheathing quality and prevents 'chunks' of it and whatever is beneath being knocked off. We paint over primer all the time - so long as it's stuck, and the paint is formulated to stick to that....But as I said, I don't think any coating will stand up to being bashed about between hull and locks for long. Given the cost saving of not having to shot blast, it seems worth a try at least.

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6 hours ago, blackrose said:

Listen to the advice above. You're wasting your money putting Jotamastic 87 over bitumen. 

 

I've used Jotamastic 87 extensively when I worked in a boat yeard and I've also got 4 coats on my widebeam. It's a great product but you need to follow the technical data sheets to the letter.

 

https://www.jotun.com/Datasheets/Download?url=%2fAG%2fAG__515__Jotamastic+87__Euk__GB.pdf

 

https://www.jotun.com/us/en/b2b/paintsandcoatings/products/Jotamastic-87.aspx

 

Reading the data sheet, you need to know exactly what you are planning to cover, then ask Jotun if it is compatible with the product you plan to use.

Hence the advice to shot blast all the old unknown "blacking" off, to start from a known surface.

 

Bod.

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Can I hijack the thread with a quick question please?

 

My boat works pretty hard all year round, especially in the winter (coal/fuel boat) and I try and dock it every year and apply 3 coats of bitumen because when out breaking ice it strips the bitumen off the water line (which is very variable depending on load)

Is epoxy tough enough to withstand a decent amount of ice breaking or am I wasting time and money, and should I stick with standard bitumen which I will continue to apply every 12 months?

 

TIA

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21 minutes ago, Bod said:

Reading the data sheet, you need to know exactly what you are planning to cover, then ask Jotun if it is compatible with the product you plan to use.

Hence the advice to shot blast all the old unknown "blacking" off, to start from a known surface.

 

Bod.

It's not at all compatible, which was why I '!?' the idea on the OP. As I said, I think the idea of J87 over anything but shotblasted steel is a dead end and a crossed wire with the yard.

HOWEVER - Ballastic Epoxy is touted by SML as to be able to be top coated with further epoxy coating. It's actually down as a primer suitable to go over bitumen, though they told me a topcoat was optional and it's fine on its own as blacking. What a time to be alive.

 

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B/F

Do you have a link to the product you intend to use?

I would be interested in seeing the data sheets for this.

 

Bod

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10 hours ago, Liam said:

Can I hijack the thread with a quick question please?

 

My boat works pretty hard all year round, especially in the winter (coal/fuel boat) and I try and dock it every year and apply 3 coats of bitumen because when out breaking ice it strips the bitumen off the water line (which is very variable depending on load)

Is epoxy tough enough to withstand a decent amount of ice breaking or am I wasting time and money, and should I stick with standard bitumen which I will continue to apply every 12 months?

 

TIA

 

If you're applying bitumen every 12 months and you don't mind doing that then I would just carry on.

 

Jotamastic 87 would certainly stand up to ice breaking better than bitumen, but whether it could withstand abrasion completely I don't know. It depends on how much ice breaking you do I suppose. Personally I wouldn't bother - if you have a system that works then stick to it. But if you do end up applying epoxy then you'll have to get all the bitumen blasted off first. Don't paint it over the bitumen.

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10 hours ago, barmyfluid said:

 

HOWEVER - Ballastic Epoxy is touted by SML as to be able to be top coated with further epoxy coating. It's actually down as a primer suitable to go over bitumen, though they told me a topcoat was optional and it's fine on its own as blacking. What a time to be alive.

 

 

I'm a bit confused. Any epoxy can go over itself? Either overcoat within the maximum overcoating time as specified in the TDS or key with an appropriate grit paper and recoat. 

 

If you've found an epoxy that can go over bitumen and does what you need it to do then good luck to you. However, I would have thought that at some point you will need to get the whole lot off and that might be a pain. But let us know how it goes.

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There are 2 types of coatings. Barrier and passive. Epoxies are barrier. They work by stopping water and oxygen getting to the surface BUT they must have excellent adhesion to the substrate ( i.e. Steel). That stops undercutting and rust penetration under the coating. They will not work well if applied over a soft single pack with poor adhesion i.e. Blacking.

Now if the OP has found some super duper snake oil type modified epoxy that will work as a barrier over soft coatings then let's see the data sheets. In 40 years since being in the epoxy formulation game, none of the big boys have EVER achieved this!

Trust me, I'm a doctor.

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18 hours ago, barmyfluid said:

Yeah, I think there were crossed wires with the yard on this one but it was worth asking about. I'm also hoping SML know what they're talking about with Ballastic Epoxy, as it's such a new product it's hard to find real world reports on performance. Being such a big hitter in the marine coatings world you'd think they wouldn't put out something that performed poorly when used as recommended.

SML a big hitter in the marine coatings market. Er, no. International, Jotun, Hempel......yes!

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12 hours ago, Liam said:

Can I hijack the thread with a quick question please?

 

My boat works pretty hard all year round, especially in the winter (coal/fuel boat) and I try and dock it every year and apply 3 coats of bitumen because when out breaking ice it strips the bitumen off the water line (which is very variable depending on load)

Is epoxy tough enough to withstand a decent amount of ice breaking or am I wasting time and money, and should I stick with standard bitumen which I will continue to apply every 12 months?

 

TIA

Yes, epoxy should cope with ice breaking but it won't cope with hitting locks like some of the protruding collars on some T&M locks. 20 tons boat hitting protruding steel/stone will take off anything. You will probably get away with a docking every three years to repair the epoxy and in general your boat will be in much better condition, no waterline bubbling rust etc.

 

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

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1 hour ago, Dr Bob said:

SML a big hitter in the marine coatings market. Er, no. International, Jotun, Hempel......yes!

 

I used Hempel and they were very specific about taking it back to the bare substrate before priming & painting.

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