Epoxy on top of bitumen?! Witchcraft!

[captain flint]

Long post coming up!

 

Summary: there's a company that has a special, proprietory 2 pack epoxy system that is claimed can be applied without grit blasting - in fact, without even needle gunning or removal of any (sound) coatings. I spoke to the guy who designed it, and am relating what he said. 

 

*

 

I've just got off the phone with a chap called Peter, whose company's website I stumbled on. He's nearing the end of his career as a chemical engineer. His company supplies specialist 2 pack epoxy coatings. He told me about a 3 coat system he thought suitable for my integral water tank. 

 

He sounded pretty convincing to me, very proud of his work and keen to explain it. He seemed much like a proud boffin than a slick salesman. But obviously I don't really know the guy. 

 

I would be interested to read reactions. I'm sure some will be dubious. I can relate to that - things that sound too good to be true tend out to be true, after all. I guess he could be a pure charlatan. But if so, he's a very good one, as he does an absolutely remarkable impression of a clued up and enthusiastic chemical engineering nerd. If anyone more technical than me wants to give them a call he seemed more than happy to discuss his product. 

 

I asked if they are manufacturers or suppliers. He said a bit of both. They use existing 2 packs on the market, but they modify them.

 

He said what he has really loved about his career is problem solving, and said they've both applied and supplied coatings (for clients to apply) for tanks in canal boats, commercial boats, super yachts, hotels, schools, and prisons, all over the world. He said they've never had to go back to fix any problems with tanks they've coated, even over periods of up to 30 years. He also said they've been used on boat hulls, but my enquiry was about my integral water tank, so we mainly discussed tanks. 

 

It's a three coat system, with zinc reinforcing in the primer, which he claimed has an anodising effect which inhibits corrosion, and glass reinforcement in at least one of the top coats, for durability and structural integrity. 

 

He said that one problem they solved was with dew points and condensation and damp surfaces. The primer is not water based and also contains no solvents, but somehow(?!) has some of the properties of a water-based system and is able to absorb some dampness off the surface, so can be applied while the boat is in the water. 

 

He said another problem was with vibration, bumps and dings. A solution was found during a job in Papua New Guinea in an area prone to earthquakes. The system is claimed to be both strong and flexible, and the tanks they coated there apparently didn't spring leaks even with a fairly severe earthquake (I don't remember how many on the richter scale, I think he said 6 point something). 

 

He said that their primer will adhere to anything, even bitumen(!). So long as it's not flaking off. He said in my case he would get rid of any loose coatings, and any rust, and degloss the bitumen with an acetone rag (I have glossy blacking in my tank). Then vacuum very carefully. And that's it! He said if the bitumen is adhering well and not flaking off there's no need to remove it. 

 

I asked about guarantees. He's now past retirement age, and they no longer apply their coatings themself. They used to offer a ten year guarantee, and says he's never been called back to a tank once it's been properly coated. Of course, that might simply mean that none of them had sprung an actual leak, rather than that the coating itself was still sound, but even so (if true), pretty reassuring. He thought that properly applied the coating should last 20 years or more, but ten at an absolute minimum. He did say there have been cases where it was not applied thickly enough, but that once rectified it's stayed the course. 

 

As they no longer do the application themself they are not able to offer any official guarantee or warranty, though. 

 

He said its easy to apply. They even have a colour system, so that each coat is a lighter colour than the last, which makes it easy to tell if each coat is thick enough. 

 

He also said it's potable and taint free, and that, unless it's being sprayed, there's no need for a respirator, as it gives off very little in the way of fumes. Obviously I would want one while deglossing, but that's another matter. 

 

He says that obviously grit blasting is wonderful when possible (eg hulls), but for the inside of a water tank, all his system needs is for any loose materials to be removed, any gloss surfaces deglossed, and a very careful vacuuming.

 

He said even if there are leaks in the tank they will be filled successfully by the primer. 

 

He said ideally any loose coating should be removed, but that even if it hadn't been, the three coats, with their flexibility and reinforcement, should basically act like a complete structure, and should be sound. Though he advised against putting that to the test.

 

Depending on cost, I think I'm going to give it a go, unless anyone can convince me otherwise. If it works as claimed it would save me a lot of time, hassle, and, potentially in the long run cost. 

[cuthound]

I would think that using epoxy over an existing coat results in an epoxy that is only adhered as strongly to the steel as the coat to which it is applied, unlike putting epoxy onto grit blasted steel, where the epoxy adheres as strongly as its designer intended.

[MtB]

First bump on the concrete of a lockside would scrape some of it off, I'd have thought, given the softness of any bitumen underneath.

 

Then water can get behind and its a downward spiral to rusting through and the boat sinking at some point in the next 35 years!

 

 

[ditchcrawler]

29 minutes ago, MtB said:

First bump on the concrete of a lockside would scrape some of it off, I'd have thought, given the softness of any bitumen underneath.

 

Then water can get behind and its a downward spiral to rusting through and the boat sinking at some point in the next 35 years!

 

 

Do you get many lock sides inside water tanks?

[captain flint]

1 hour ago, cuthound said:

I would think that using epoxy over an existing coat results in an epoxy that is only adhered as strongly to the steel as the coat to which it is applied, unlike putting epoxy onto grit blasted steel, where the epoxy adheres as strongly as its designer intended.

I would think that, too... But then there's the significant caveat that I was actually talking to the designer himself...! 

32 minutes ago, MtB said:

First bump on the concrete of a lockside would scrape some of it off, I'd have thought, given the softness of any bitumen underneath.

 

Then water can get behind and its a downward spiral to rusting through and the boat sinking at some point in the next 35 years!

 

 

Yes. Peter didn't think that would be an issue, but to be honest I'm going to speak to Peter again. I would have thought the best plan would be to remove all the bitumen and needlegun the tank, rather than apply over the top. 

[ditchcrawler]

I have had my hull epoxied over bitumen with no blasting. I don't pretend id is as good as 2 pack on blasted steel but I do believe it is superior to just slapping bitumen on. I am on my way to have it done again.

[captain flint]

34 minutes ago, MtB said:

First bump on the concrete of a lockside would scrape some of it off, I'd have thought, given the softness of any bitumen underneath.

 

Then water can get behind and its a downward spiral to rusting through and the boat sinking at some point in the next 35 years!

 

 

The designer's view was that it would adhere and that, once all three epoxy coatings are properly applied, their structural properties would mean that they, in effect, form a tank themself. One that's flush, and ideally adhered to, the tank proper (plus any coatings), but that even if some of it stops adhering in places, the epoxy should not crack. Under such circumstances I still find it hard to believe that condensation in between the epoxy and the bitumen/steel wouldn't be a potential issue, though. Hence thinking removing bitumen and then needle gunning would be better

2 minutes ago, ditchcrawler said:

I have had my hull epoxied over bitumen with no blasting. I don't pretend id is as good as 2 pack on blasted steel but I do believe it is superior to just slapping bitumen on. I am on my way to have it done again.

If it sticks it sticks! Has it stayed on?! If so for how long? And what epoxy were you using? 

[matty40s]

48 minutes ago, ditchcrawler said:

Do you get many lock sides inside water tanks?

Have you not seen him steer?

[wakey_wake]

42 minutes ago, captain flint said:

Under such circumstances I still find it hard to believe that condensation in between the epoxy and the bitumen/steel wouldn't be a potential issue, though.

Possibly one of the coats is a sufficiently effective moisture vapour barrier. Metals are good at this, so maybe the zinc rich layer? Except that sounds like a slurry that has set, not a continuous film.

 

Condensation doesn't just magically appear from nowhere, it has to get in. If it can't go through the paint layers it will have to track in from an accessible edge, which seems likely to be really slow until the dreaded bubbling-flaking phase starts to mechanically open access?

[captain flint]

9 minutes ago, wakey_wake said:

Possibly one of the coats is a sufficiently effective moisture vapour barrier. Metals are good at this, so maybe the zinc rich layer? Except that sounds like a slurry that has set, not a continuous film.

 

Condensation doesn't just magically appear from nowhere, it has to get in. If it can't go through the paint layers it will have to track in from an accessible edge, which seems likely to be really slow until the dreaded bubbling-flaking phase starts to mechanically open access?

Yes I was thinking about this issue of where condensation might get in. But then, not very scientifically, I was just thinking it might somehow just... Find a way! Liquids and vapours seem good at that. I don't quite follow your comment about it being like a slurry that's set. As far as I understand (not very) it's a two pack epoxy somehoe6 enriched/reinforced with zinc. I didn't ask exactly how. If I had I suspect I might not have understood the answer! 

[wakey_wake]

53 minutes ago, captain flint said:

[...] I was just thinking it might somehow just... Find a way! Liquids and vapours seem good at that.

Oh they're very good at it when there is a way, and also good at expanding a chink into a bubbling hole, but the paint technologists apparently dedicate a lot of study to the battle.

I don't have more details, except to know that sometimes when fighting rust the trick is to lose so slowly that it looks like winning. 😉

 

53 minutes ago, captain flint said:

I don't quite follow your comment about it being like a slurry that's set. As far as I understand (not very) it's a two pack epoxy somehoe6 enriched/reinforced with zinc. I didn't ask exactly how. If I had I suspect I might not have understood the answer! 

 

My simplistic understanding is that the mixed paint is a slurry of particles in some liquid, which is in turn a solution of stuff in a solvent (here perhaps water). When the epoxy sets, I think of that as a "slurry that's set". There may be a better term.

 

I'm sceptical that metallic zinc trapped in an epoxy matrix can function in the usual sacrificial way that galvanised steel uses, unless something breaks the encapsulation of the zinc; and I also doubt that it makes as effective a barrier against water vapour and oxygen as a metallic film.

 

However there are paint systems that lay down sufficient metallic zinc to be effective.

 

Quote

Witchcraft!

"any sufficiently advanced technology is indistinguishable from magic"

[captain flint]

The paint designer specifically said it's not water based and it's solvent free, and that it's is an exothermic* chemical reaction that makes it cure

 

*I think that's what he said. Something thermic anyway

[LadyG]

13 hours ago, captain flint said:

I would think that, too... But then there's the significant caveat that I was actually talking to the designer himself...! 

Yes. Peter didn't think that would be an issue, but to be honest I'm going to speak to Peter again. I would have thought the best plan would be to remove all the bitumen and needlegun the tank, rather than apply over the top. 

Obviously, because unless you do that you cant inspect the steel.

[Gybe Ho]

11 hours ago, wakey_wake said:

I'm sceptical that metallic zinc trapped in an epoxy matrix can function in the usual sacrificial way that galvanised steel uses, unless something breaks the encapsulation of the zinc

 

 

That "something" would be a scratch or the baseplate scraping along the canal bed.

[captain flint]

I have a fair idea already as I was in there not so long ago, 3 years I think, scraping off the bitumen and reapplying. It had a few 1-2mm pits under/ near the water intake, some superficial patches on the base and a little rust buildup along the welded seams, but other than that was pretty good. 

 

I've recently inspected using an endoscope camera. Not easy to get a perfect idea, but it looks in pretty good nick still, except for under the water intake, where some of it has come away. I've occasionally run the tank dry so I figure the water splashing down onto the bitumen hasn't exactly helped. 

 

The paint designer seems to think this product can even be used on, and to repair, corroded and effectively leaking tanks. 

 

Here's the page on canal boats, if you're interested:

 

https://www.specialist-coatings.co.uk/narrowboats-barges-wide-beams-canal-boats-houseboats-leisure-cruisers-general-water-craft/

 

 

Edited Thursday at 10:24 by captain flint

[Gybe Ho]

20 minutes ago, captain flint said:

The paint designer specifically said it's not water based and it's solvent free, and that it's is an exothermic* chemical reaction that makes it cure

 

 

The curing process for epoxy is inherently exothermic, so the paint you are researching is not novel in that respect.

 

I would challenge the paint designer about the claim the paint has neither solvents or water. One has to wonder what else is used.

[Llamedos]

I had some dealings with Specialist Coatings a couple of years ago. I got a quotation for their stuff and I have to say it was eye wateringly expensive but I was still up for giving it a go -  before I parted with my cash, however, I wanted a few questions answered mainly about how to use it, storage time, support from them etc. They responded at first but when I asked for a hard copy of their guide to applying the stuff it all went quiet and they stopped responding to my emails - so I walked away. I think someone else on here had a similar experience - ask too many questions and it seems to irritate them.

 

In the end I got the job done by the chap who did my last blacking using ordinary bitumen water tank paint again. In think I had just lost patience with it all by then and wanted the job done and out of the way.

Edited Thursday at 11:15 by Llamedos
clarification

[captain flint]

24 minutes ago, Llamedos said:

I had some dealings with Specialist Coatings a couple of years ago. I got a quotation for their stuff and I have to say it was eye wateringly expensive but I was still up for giving it a go -  before I parted with my cash, however, I wanted a few questions answered mainly about how to use it, storage time, support from them etc. They responded at first but when I asked for a hard copy of their guide to applying the stuff it all went quiet and they stopped responding to my emails - so I walked away. I think someone else on here had a similar experience - ask too many questions and it seems to irritate them.

 

In the end I got the job done by the chap who did my last blacking using ordinary bitumen water tank paint again. In think I had just lost patience with it all by then and wanted the job done and out of the way.

 

When I spoke to Peter, the head fella, on the phone he told me he'd had two strokes in the last few years. So I guess it might have been health issues that caused him to go quiet, rather than irritation. 

 

Anyway he's said he'll be sending me a full guide before any purchase happens. I can't imagine I'd want more than the odd page printed out, which I can do myself

 

1 hour ago, Gybe Ho said:

The curing process for epoxy is inherently exothermic, so the paint you are researching is not novel in that respect.

That's what I thought but I wasn't sure if I was misremembering /misjargoning. The designer did say that the 2 pack element is one that's on the market, albeit significantly modified. 

 

1 hour ago, Gybe Ho said:

I would challenge the paint designer about the claim the paint has neither solvents or water. One has to wonder what else is used.

 I'm expecting the data sheet before too long. There are solvent free 2 pack epoxy systems out there, though, so I expect it's one of them

Jotomastic is solvent free... 

24 minutes ago, Llamedos said:

 

In the end I got the job done by the chap who did my last blacking using ordinary bitumen water tank paint again. In think I had just lost patience with it all by then and wanted the job done and out of the way.

I did my own last time. The only reputable option I'm aware of anywhere within reach for getting it redone (as opposed to redoing it myself) would charge £1200, which I understand, having done the job myself. It's a pig. But it is supposed to be redone every 3-5 years. £1200 isn't peanuts in itself, but if spending more might been I don't have to open up the bloody thing again for ten or fifteen years that would be amazing! And it might even represent better value for money in the long term

 

 

Edited Thursday at 11:38 by captain flint

[Hunter1]

Very curious to follow this thread - sounds promising to me Captain Flint.

 

After considering every option, I now just scrape the rust off when the water gets too brown... and I don't drink from the tank! A product that can be applied over whatever they put on there in 1995, that is suitable to potable water... Yes please!

 

My thoughts are - someone must have been working on a solution (such a common issue), and it sounds like you might have found the guy. Keep us updated if you give it a go?

[captain flint]

I do drink from my tank, but I have a reverse osmosis filter fitted. There are a few available, I got mine from Offgrid Water. Main things to check are if they can cope with low pressure water feed, and if they re-mineralise the water. 

 

I'll keep you posted but you'll have to be patient - I'm leaning towards redoing my tank next year, not this. Plus - and I guess this is the real kicker - even if it goes on well and looks good I won't really be able to report much until the coating has been in place for a few years! 

1 hour ago, Hunter1 said:

I now just scrape the rust off when the water gets too brown... and I don't drink from the tank!

Blimey. Do you not even use tank blacking?! Don't you worry about corrosion? Having recently helped out a neighbour who had to pull up his floors, and dry and treat his bilge, tank leaks are no joke. 

[Llamedos]

@captain flint I just remembered that I too started a thread on this forum a couple of years back about Specialist Coatings and this product. Here it is if you're interested in having a read...

 

Specialist Coatings

 

The person I was speaking to who eventually stopped replying was Alison Lambert-Gorwyn.

Edited Thursday at 13:48 by Llamedos

[wakey_wake]

26 minutes ago, captain flint said:

I'll keep you posted but you'll have to be patient - I'm leaning towards redoing my tank next year, not this. Plus - and I guess this is the real kicker - even if it goes on well and looks good I won't really be able to report much until the coating has been in place for a few years! 

 

The website gives me the impression "if you have to ask the price, you can't afford it".

Perhaps they don't want to publish the price and coverage rates for some reason?

Perhaps you can get permission to share much more, or at least some specific further, detail of what you are told?

[Russ T]

To quote the great muppet.......

 

 

Quote

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.

My sentiment exactly. Lets see the data sheet. Which should be readily available on that website IMHO.

[Llamedos]

34 minutes ago, wakey_wake said:

 

The website gives me the impression "if you have to ask the price, you can't afford it".

Perhaps they don't want to publish the price and coverage rates for some reason?

Perhaps you can get permission to share much more, or at least some specific further, detail of what you are told?

 

They quoted me £601.63 inc VAT and P&P. My tank holds 950ltrs or thereabouts so quite a big 'un.

 

The tin of Rylard Bitumen Water Tank Paint which was eventually used was about £25 from memory.

 

Not comparing like with like I know but nevertheless.😬

[captain flint]

48 minutes ago, Llamedos said:

 

They quoted me £601.63 inc VAT and P&P. My tank holds 950ltrs or thereabouts so quite a big 'un.

 

The tin of Rylard Bitumen Water Tank Paint which was eventually used was about £25 from memory.

 

Not comparing like with like I know but nevertheless.😬

If - and it's *the* big if - the coating works as advertised, then that price would seem well worth not having to get in there every 3-5 years! 

1 hour ago, Russ T said:

To quote the great muppet.......

 

 

My sentiment exactly. Lets see the data sheet. Which should be readily available on that website IMHO.

I hope to be able to share them soon. Despite what the designer told me, my plan would be to remove all the bitumen and needle gun the tank. Tbh the main thing for me is it's impossible to grit blast inside the tank. Any reliably adhering epoxy coating without grit blasting sounds great. There are plenty of folk on here who reckon they've managed it, but most reliable folks I know reckon it's grit blast or bust, when it comes to being confident on an epoxy coating adhering. 

1 hour ago, Russ T said:

To quote the great muppet.......

 

 

My sentiment exactly. Lets see the data sheet. Which should be readily available on that website IMHO.

The guy I spoke to did seem to think that even if the bitumen underneath were to lose adhesion in a few places, the epoxy on top would have sufficient structural integrity and give to mean no cracks, leaks, or peeling. But like I say, i would plan to remove the bitumen completely.