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Water tank re-paint time!


sue.stew
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Anyone have the answer as to which is the best product to use on our water tank after preparing the surface? Neutrarust 661, Fertan and Vactan have been suggested but I would love to hear of any tried and tested ( and successful) projects.

Many thanks

 

 

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12 minutes ago, sue.stew said:

Anyone have the answer as to which is the best product to use on our water tank after preparing the surface? Neutrarust 661, Fertan and Vactan have been suggested but I would love to hear of any tried and tested ( and successful) projects.

Many thanks

 

I have no experience of Neutrarust, but of the other two, Vactan is the cleaner option. Fertan, in my experience, needs a lot of rinsing. 

 

 

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Not much help but, I used Vactan for the first time last September, I had to leave it a few weeks before blacking due to Covid restrictions.

Then a couple of weeks between each blacking coat, again Covid.

Because the boat has been winterised I haven't had chance to fill the tank.

Picture is about 1/2 hour after applying the Vactan.

Don't forget to do the underside of the foredeck. Condensation often gathers there and can lead to rust.

When I eventually get back to the boat I have some Aqua Clean - Puriclean to flush through the system including the calorifier.

 

Water Purification - Aqua Clean - Puriclean | Leisureshopdirect

Puriclean 400g Tub - Water tank Cleaner

 

IMGP4936.JPG

Edited by Ray T
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At the risk of being Captain Obvious, I presume that you are applying some special tank-paint after the rust-treatment? I guess that  which ever product that is will dictate what to use underneath it. The video I've seen showed a bitumenous coating bit I am sure that there are others as tanks are often lined and painted in industry. (not to mention classic motorcycles, but not usually for drinking water!)

 

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11 minutes ago, MartinW said:

At the risk of being Captain Obvious, I presume that you are applying some special tank-paint after the rust-treatment? I guess that  which ever product that is will dictate what to use underneath it. The video I've seen showed a bitumenous coating bit I am sure that there are others as tanks are often lined and painted in industry. (not to mention classic motorcycles, but not usually for drinking water!)

 

 

 

Bitumen coatings are allowed, but aren't up to the standards of today, for potable water. Older boats will have a bitumen coating and can continue to use them. I've recently cleaned off all the bitumen in my water tank and don't intend using bitumen again. There are epoxy coatings that can be used, but to be effective, it is necessary to have the steel sand/shot blasted to a suitable degree. I'm still pondering the epoxy route. 

 

 

Edited by Higgs
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Thanks for the useful info. I would like to avoid going down the bitumen route. We emptied the tank just before christmas, cleaned it out ready to tackle in the spring.  Last time , we had a marina sort it but the paint only lasted a year. If you have any paint recommendations that would be suitable please post them, thanks all.

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2 hours ago, sue.stew said:

Anyone have the answer as to which is the best product to use on our water tank after preparing the surface? Neutrarust 661, Fertan and Vactan have been suggested but I would love to hear of any tried and tested ( and successful) projects.

Many thanks

 

 

 

The best treatment will be several coats of water potable epoxy. Trouble is it's only available in  minimum15 litre quantities and it's quite expensive. Epoxies are more technical paints than those used by the average narrowboater. They have to be mixed properly in the correct quantites, and overcoated according to min/max overcoating times based on temperature. It's perfectly possible for an amateur to use epoxies but you must read the data sheets - you can't just slap them on.

 

Tankguard DW - SML Protective Coatings

 

The other issue is that like most epoxy paints you have to prep the steel to a standard of Sa 2.5. You can do it without blast cleaning using an angle grinder and wire wheels, etc, but it's hard work.

Sa 2½ Very thorough blast cleaning. Mill scale, rust and foreign matter shall be removed to the extent that the only traces remaining are slight stains in the forms of spots or stripes. Finally, the surface is cleaned with a vacuum cleaner, clean dry compressed air or a clean brush.

 

Edit: The answer to the next question is no. You don't use Vactan, etc, under epoxy. 

Edited by blackrose
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  • 1 month later...

@blackrose

 

Have you used the Jotun Tankguard epoxy on your tank? I’m interested to find someone who’s got some real world experience of applying it to wire brushed/sanded steel. I emailed Jotun about this and they said: (I also asked if you could undercoat with Jotamastic 90 which is waaaay more surface tolerant and can be applied to manually prepared surfaces)

 

We've never tested Tankguard DW onto manually prepared surfaces, but as you know the quality of surface preparation has a direct influence on the expected lifespan of the coating.  There's no figure we can give for reduction of lifespan, all we can say is that the expected lifespan will be significantly reduced.

As for the Jotamastic 90 being used as a primer and taking advantage of its surface tolerance, this would not be recommended.   

When coating tanks, especially drinking water tanks, it is of paramount importance to observe correct surface preparation and coating application.”


Obviously they just re-said what it says in the Tankguard application guide. Proper surface prep is obviously required to get the maximum life from the coating but I wonder, as long as any residual coating has been fully cleaned off the tank, how long the epoxy would last. Even if it’s 5 or 6 years (??) As opposed then it’s probably worth it. Considering it’s safer than bitumen. 
 

You can also get the ‘Rylards’ (same as Epicol SF) version which per litre is about the same price as Jotun but you can get it in 4.5l size which costs about £100. 
 

https://www.boatpaint.co.uk/acatalog/Spencer-Coatings-Epicol--Water-Tank-Coating-.html
 

https://www.promain.co.uk/hygiene-paint-antibacterial-paint/potable-paints/axalta-epicol-sf-solvent-free-epoxy.html
 

I think the main thing to consider would be making sure it’s warm enough (ideally 15+ degrees!) and no condensation/dew forms in the tank whilst the coating is curing. This would probably be possible to do on a boat in the water in the middle of summer. Or if you’ve got shorepower you could could dangle a heater in there overnight... 

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Thanks for the information.  I'm considering the Rylards option at the moment. Think it's worth paying the extra. If it doesn't work out will definitely look into a replacement plastic tank.

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That’s what I’m thinking. To be fair £100 for the 4.5l from Promain is not too bad. I’m now considering buying second hand sand blaster and air compressor to do it properly. If you could get both off eBay for £100 ish each, plus paint, plus media maybe £400 in total and then recoup some of the cost by selling the compressor and blaster again. 
 

That’s pretty good for a potential 10+ year coating. 

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39 minutes ago, WillCful said:

That’s what I’m thinking. To be fair £100 for the 4.5l from Promain is not too bad. I’m now considering buying second hand sand blaster and air compressor to do it properly. If you could get both off eBay for £100 ish each, plus paint, plus media maybe £400 in total and then recoup some of the cost by selling the compressor and blaster again. 
 

That’s pretty good for a potential 10+ year coating. 

 

Grit blasting in such a confined space will be difficult and unpleasant. A needle gun might be better, and is a very close second best for preparation. A wire cup brush in an angle grinder should be just about ok with a surface tolerant epoxy primer.

 

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

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1 hour ago, WillCful said:

and then recoup some of the cost by selling the compressor and blaster again. 

Or, recoup even more by being richly rewarded for coming and doing mine once you've got the hang of it... :D

 

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36 minutes ago, dmr said:

 

Grit blasting in such a confined space will be difficult and unpleasant. A needle gun might be better, and is a very close second best for preparation. A wire cup brush in an angle grinder should be just about ok with a surface tolerant epoxy primer.

 

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

 

It will! But a needle gun is not necessarily the same finish as a blaster. You might really need a blaster to get the fine textured surface that the paint will best adhere to.

 

8 minutes ago, Sea Dog said:

Or, recoup even more by being richly rewarded for coming and doing mine once you've got the hang of it... :D

 

 

If it works, you've got yourself a deal! Actually since a lot of air compressors run off small combustion motors you wouldn't even need a 240v supply... 

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1 hour ago, WillCful said:

 

It will! But a needle gun is not necessarily the same finish as a blaster. You might really need a blaster to get the fine textured surface that the paint will best adhere to.

 

 

If it works, you've got yourself a deal! Actually since a lot of air compressors run off small combustion motors you wouldn't even need a 240v supply... 

 

We've had the boat grit blasted, and I have also done a fair bit of needle gunning. I would say a needle gun is a very very close second best, blasting and gunning (scaling) are similar in that they bth work by making many many impacts. Wire brushing is very much a poor third as it scrapes and polishes the surface but does not really get into the pits, but it's still pretty good and a 1000 times better than no serious prep and just painting with Vactan.

 

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

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3 minutes ago, dmr said:

 

We've had the boat grit blasted, and I have also done a fair bit of needle gunning. I would say a needle gun is a very very close second best, blasting and gunning (scaling) are similar in that they bth work by making many many impacts. Wire brushing is very much a poor third as it scrapes and polishes the surface but does not really get into the pits, but it's still pretty good and a 1000 times better than no serious prep and just painting with Vactan.

 

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

 

Thanks Dave, grit blasting would be a bit miserable. I would be concerned about the size of the needles, not small enough to get into all the little pits... 

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14 minutes ago, WillCful said:

 

Thanks Dave, grit blasting would be a bit miserable. I would be concerned about the size of the needles, not small enough to get into all the little pits... 

 

Epoxy really is good stuff. Ive done front deck, gas and side lockers with a wire cup brush and so far no real failures after several years. I suspect a tiny bit of rust at the bottom of a pit will not be a problem. Once the epoxy is on any further rusting will be stopped, so unless its a sigificant bit of rust than can break loose or continue to grow for a short while and puncture the epoxy, it should be fine.

 

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

 

 

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1 hour ago, WillCful said:

 

If it works, you've got yourself a deal! Actually since a lot of air compressors run off small combustion motors you wouldn't even need a 240v supply... 

 

Oh I can make sure I'm good for the 240v supply! I wait in anticipation... :D

 

SML, who were referred to earlier regarding their water tank epoxy, appear to be quite up with the hunt on prep tolerant epoxy: they have also introduced a bitumen tolerant 2 pack epoxy for hull blacking which one of our members used last year with machine prep but without blasting. It looked pretty good after 6 months in the water when it came out again to check last October, but I haven't seen it since and 6 months wet wasn't really enough to properly judge. I'm intending to black my own boat with it in May if the results still look better than bitumen when I do finally get back to the mooring. Drifting slightly off topic there, but it does perhaps add some info about SML's offerings.

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On 19/01/2021 at 14:36, Higgs said:

 

 

Bitumen coatings are allowed, but aren't up to the standards of today, for potable water. Older boats will have a bitumen coating and can continue to use them. I've recently cleaned off all the bitumen in my water tank and don't intend using bitumen again. There are epoxy coatings that can be used, but to be effective, it is necessary to have the steel sand/shot blasted to a suitable degree. I'm still pondering the epoxy route. 

 

 

 

That's not correct. Epoxies can be applied without grit or shot blasting. Jotun Tankguard DW water potable epoxy for example, requires steel surface prep to Sa2.5 which is easily achievable with power tools.

 

 

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On 09/03/2021 at 10:40, dmr said:

 

Grit blasting in such a confined space will be difficult and unpleasant. A needle gun might be better, and is a very close second best for preparation. A wire cup brush in an angle grinder should be just about ok with a surface tolerant epoxy primer.

 

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

 

Correct.

 

I've used epoxy paints extensively both at work and on my own boat including applying a water potable epoxy in my water tank. Lots of the prep was done with an angle grinder and wire wheels and it's all fine. The bilges of two old Thames steam boats that we epoxied were all prepped with angle grinders because grit blasting was too aggressive for the riveted steel. That was nearly 10 years ago and as far as I know it's still good.

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For anyone thinking of using a water potable epoxy in their tank, I think the biggest issue is finding a product in small enough quantities. Tankguard DW is only available in 20 litre quantity minimum as far as I'm aware. I'm not sure about others.

 

And if you do epoxy your tank don't use vactan for gawd's sake!

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1 hour ago, blackrose said:

For anyone thinking of using a water potable epoxy in their tank, I think the biggest issue is finding a product in small enough quantities. Tankguard DW is only available in 20 litre quantity minimum as far as I'm aware. I'm not sure about others.

 

And if you do epoxy your tank don't use vactan for gawd's sake!

 
15l I think. The best alternative I’ve found is Epicol SF, 4.5l from Promain for about £100. Comes in 3 colours too ?

 

1 hour ago, blackrose said:

 

That's not correct. Epoxies can be applied without grit or shot blasting. Jotun Tankguard DW water potable epoxy for example, requires steel surface prep to Sa2.5 which is easily achievable with power tools.

 

 

 

Are you certain? I didn’t know what these standards meant but googled it... this for example:

https://www.rust.co.uk/understanding-surface-preparation-grades-when-painting-steel
Says that sa2.5 specifically relates to blast cleaning.
 

I used angle grinder/wire wheels to do the bilge in my boat and then epoxied it but it was with the Jotamastic 90 which Jotun tells us is more surface tolerant...

 

How long ago did you epoxy the tank in your boat? Did you use the Tankguard DW? Hope you don’t mind me asking I’m just really keen for some real world experience. It’s fine for all the data sheets to say that it requires shot blasting but even if it lasts five or six years without you’d be made up!

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1 hour ago, blackrose said:

 

Correct.

 

I've used epoxy paints extensively both at work and on my own boat including applying a water potable epoxy in my water tank. Lots of the prep was done with an angle grinder and wire wheels and it's all fine. The bilges of two old Thames steam boats that we epoxied were all prepped with angle grinders because grit blasting was too aggressive for the riveted steel. That was nearly 10 years ago and as far as I know it's still good.

 

I don't completely agree. Wire brushing (angle grinder) is not nearly as good as blasting/needle scaling as it leaves a much smoother/polished surface and does not get fully into some pits. However wire brushing and epoxy is still pretty damn good and the absence of shot blasting should not be a reason not to use epoxy. So actually I suppose I do agree.

 

Wire brushing to almost bare steel and then epoxy is 1000 times better than Vactan. We certainly agree here.

 

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

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20 hours ago, WillCful said:

 
15l I think. The best alternative I’ve found is Epicol SF, 4.5l from Promain for about £100. Comes in 3 colours too ?

 

 

Are you certain? I didn’t know what these standards meant but googled it... this for example:

https://www.rust.co.uk/understanding-surface-preparation-grades-when-painting-steel
Says that sa2.5 specifically relates to blast cleaning.
 

I used angle grinder/wire wheels to do the bilge in my boat and then epoxied it but it was with the Jotamastic 90 which Jotun tells us is more surface tolerant...

 

How long ago did you epoxy the tank in your boat? Did you use the Tankguard DW? Hope you don’t mind me asking I’m just really keen for some real world experience. It’s fine for all the data sheets to say that it requires shot blasting but even if it lasts five or six years without you’d be made up!

 

Thanks for the Epicol SF info, I didn't know about that one.

 

Yes, I'm certain that Sa2.5 can be achieved with power and hand tools but correctly it's referred to as St2 and St3. I used to do it for a living and the boss used to give us bollockings if we didn't get the steel clean! It's very easy to make the mistake of polishing hard rust scale rather then completely removing it, which then looks like bare steel so you need to use a welder's chipping hammer too.

 

Surface preparation grades (wartsila.com)

 

I've posted a picture somewhere on another thread about a gas locker which shows surface prep at the bottom of a badly corroded locker using an angle grinder/wire wheels. It's not perfect but it's good enough for a surface tolerant epoxy. I did those lockers and my gas locker 2 years ago. The water tank was done 5 years ago with a water potable epoxy from a company called Reactive Resins which they imported from Italy. It was the only product I could find in reasonably small quantities at the time but they've since stopped selling it.   

Edited by blackrose
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20 hours ago, dmr said:

 

I don't completely agree. Wire brushing (angle grinder) is not nearly as good as blasting/needle scaling as it leaves a much smoother/polished surface and does not get fully into some pits. However wire brushing and epoxy is still pretty damn good and the absence of shot blasting should not be a reason not to use epoxy. So actually I suppose I do agree.

 

Wire brushing to almost bare steel and then epoxy is 1000 times better than Vactan. We certainly agree here.

 

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

 

Ok, I'm not going to disagree. I don't think I actually said that a wire brush on an angle grinder was as good as grit blasting, I just said that blasting wasn't necessarily required as long as your power tool prep was good enough. He's a picture of that locker bottom, prepped with an angle grinder and wire wheels. Not perfect but not bad and certainly good enough for the epoxy. I think I actually carried on a bit after taking that picture and tried to get the bits of rust out of the corners which is the most difficult bit. I used a narrow wire brush on a drill for that. Some will say it's too polished but in my experience the Jotamastic sticks to it very well. 

 

image.png.af4b98cf7d233300f37fce5b409a88dc.png

Edited by blackrose
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