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Hi

We recently repainted our water tank, we drained it, scraped out all the rubbish, treated it with fertan, did one coat of paint then when touch dry we did a second coat. We’ve filled and drained the tank twice but still noticed a chemical smell and taste! We had to leave it for a few weekends but when I drained it the other day I noticed patches where the metal was bare and rusty. The water had an oily film on top and the sides and base of the tank feel oily. Have we missed a stage out somewhere? Can I rub down the affected areas and start again with them? The photo below is typical but I couldn’t add anymore.

 

 Thanks 

stuart 0AD1CD04-78CC-4C10-905E-85FE37AC6772.jpeg.6852b270450c60a259377f893b39c86d.jpeg

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Was the temperature high enough for Fertan to work properly and if so did you wash the Fertan residue off before blacking.

 

Was the temperature high enough to prevent condensation on the surface as blacking proceeded and was the blacking properly dry.

  • Greenie 2
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Hi

The temperature was fine it certainly wasn’t cold, we didn’t rinse the tank after using the fertan and I don’t remember any condensation prior to blacking we even had a little blow heater down there. We used rylard water tank paint which we’d seen on a few YouTube videos. The paint people suggested the tank wasn’t properly clean prior to painting. Question is what do we do now?

 

 Thanks 

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1 hour ago, Stu penny said:

scraped out all the rubbish,

You reallly have to do more than just scrape out all the rubbish. Fertan (or other rust converters) will do their bit, but to get the coating to key to the steel you really need to remove as much rust and scale as you can. Grit blasting is best, but not usually practical for a water tank, so you have to do your best with grinding disks, flap wheels, wire brushes (on drill or angle grinder) or needle gun to get the surface as clean as you can before applying the Fertan.

Fertan has to be rinsed off before painting, which is why many prefer Vactan which can just be painted over.

 

Looking at the amount of rust which has come through in a short time, I fear there is no alternative for you but to start again.

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I use a battery multi tool......and slice with the blade like a power chisel to remove the blacking.

You need a lot of blades as they heat and melt the blacking.

 

Then.....flap wheels......

 

Sorry....but I think you're back to square one.....

 

 

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Hi

thanks for that we did get wire brushes and drill wire brush bits on it. I’m guessing it’s the not washing down after using the fertan. Do I have to try and get off the paint we have applied or can I just to fix the patches where the rust is?

 Thanks 

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29 minutes ago, Stu penny said:

we didn’t rinse the tank after using the fertan

 

And that is exactly why the paint didn't stick.  Fertan leaves a powdery residue on the surface that needs rinsing off.

 

If ever there was a place to read the instructions, doing the inside of your drinking water tank would be it!

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3 hours ago, Stu penny said:

Hi

The temperature was fine it certainly wasn’t cold, we didn’t rinse the tank after using the fertan and I don’t remember any condensation prior to blacking we even had a little blow heater down there. We used rylard water tank paint which we’d seen on a few YouTube videos. The paint people suggested the tank wasn’t properly clean prior to painting. Question is what do we do now?

 

 Thanks 

Having used that product, I would not consider using it, in any other months than July or August.  I did our tank in May, it took a fortnight to dry enough to replace the tank lid.

All I can suggest is to scrape out as much as you can, redo the Fertan as per Fertans instructions, redo the paint as per Rylard instructions.  Gentle air movement into and out of the tank will help the drying, which in my experience, this time of year, will be at least 4-6 weeks.

Paint needs to dry from the base to the top, just being "touch dry" means the top of the paint is dryish, but under that it's still wet, meaning the solvent has to get through the ever thickening top.

 

Bod

PS. Check the inside of the dip tube(if fitted) for rust build up, mine was almost solid, and had to be replaced.

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19 minutes ago, Bod said:

Having used that product, I would not consider using it, in any other months than July or August.  I did our tank in May, it took a fortnight to dry enough to replace the tank lid.

All I can suggest is to scrape out as much as you can, redo the Fertan as per Fertans instructions, redo the paint as per Rylard instructions.  Gentle air movement into and out of the tank will help the drying, which in my experience, this time of year, will be at least 4-6 weeks.

Paint needs to dry from the base to the top, just being "touch dry" means the top of the paint is dryish, but under that it's still wet, meaning the solvent has to get through the ever thickening top.

 

Bod

PS. Check the inside of the dip tube(if fitted) for rust build up, mine was almost solid, and had to be replaced.

If it is only touch dry when you get into the tank to do second coat the paint will bubble where you step on the bottom of the tank.

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23 minutes ago, Stu penny said:

As you might’ve guessed I’m a newbie what’s the best way to remove it can any sort of tar removal liquid be used or is it a case of mechanical scraping?

 

 Thanks 

 

Probably scrape as much as you can and then use the liquid to remove the residue so it can be cup brushed/disked without the blacking melting and clogging the brush/disk

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32 minutes ago, Tony Brooks said:

 

Probably scrape as much as you can and then use the liquid to remove the residue so it can be cup brushed/disked without the blacking melting and clogging the brush/disk

Could he use a heat gun to soften it? Bit like you do with oil paints ... assuming he has mains available ...

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I'd be very careful about following the earliest advice to use flap wheels and grinding disks (grinding disks really?)

 

They can remove mm of good steel without you even realising. Think about any hull survey you've read or chalked on hull thickness figures you've seen. Every tenth of a mm of steel is precious. You don't want to take off good steel especially on any below waterline areas of the tank.

 

Stick to wire wheels, scrapers, hot air gun, or any other methods that will get it back to bare metal without damaging the steel. I know it's a pain but to remove fresh blacking you're going to have to experiment to see what works best. 

 

Personally if it's very difficult to get off then I'd leave any bitumen residue to dry and cure before repainting. You'll be doing it all again in a few years anyway.

Edited by blackrose
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15 hours ago, Alan de Enfield said:

 

In addition to the application conditions (mentioned by Tony) was the paint the 'proper stuff' for use on Potable water tanks ?

 

It's the same stuff. The only difference is that the potable water tank bitumen has had tests done on it to certify it's water potable. That's why it's twice the price.

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4 hours ago, blackrose said:

 

It's the same stuff. The only difference is that the potable water tank bitumen has had tests done on it to certify it's water potable. That's why it's twice the price.

 

At the time, the OP simply said "paint", it could have been emulsion, Dulux gloss or even Hammerite, it was only later that the type was defined.

 

20 hours ago, Stu penny said:

We recently repainted our water tank, we drained it, scraped out all the rubbish, treated it with fertan, did one coat of paint then when touch dry we did a second coat.

 

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5 hours ago, blackrose said:

I'd be very careful about following the earliest advice to use flap wheels and grinding disks (grinding disks really?)

 

They can remove mm of good steel without you even realising. Think about any hull survey you've read or chalked on hull thickness figures you've seen. Every tenth of a mm of steel is precious. You don't want to take off good steel especially on any below waterline areas of the tank.

 

Stick to wire wheels, scrapers, hot air gun, or any other methods that will get it back to bare metal without damaging the steel. I know it's a pain but to remove fresh blacking you're going to have to experiment to see what works best. 

 

Personally if it's very difficult to get off then I'd leave any bitumen residue to dry and cure before repainting. You'll be doing it all again in a few years anyway.

Diesel takes bitumen off .

Not sure I would use it in a water tank though

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2 hours ago, Alan de Enfield said:

 

At the time, the OP simply said "paint", it could have been emulsion, Dulux gloss or even Hammerite, it was only later that the type was defined.

 

 

 

Ok I see. I'd given the OP some credit and  assumed they'd used bitumen. Nobody has ever painted their water tank with Hammerite, Dulux gloss or water based emulsion surely? Still I suppose it's best to clarify before making assumptions.

1 hour ago, Tonka said:

Diesel takes bitumen off .

Not sure I would use it in a water tank though

 

Yes I thought about paint stripper but getting rid of every trace might be a nightmare

Edited by blackrose
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2 minutes ago, Stu penny said:

Hi 

We’ll have to wait and see !thanks I was wondering about a chemical paint remover and had heard about diesel but I’m not sure about any of that in a water tank. Was going to see if you can get perhaps a wire brush grinder disc???

 

 

You can, it is called a twisted knot cup brush. Screwfix and Toolstation sell them. Remember it will tend to melt the bitumen and clog, that is why I suggested that you need to scrape the bitumen off first. I think it is likely to just smear the bitumen so you may still need a solvent.

 

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Edited by Tony Brooks
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I’d be tempted to start with heat gun and scraper as suggested earlier. Might be the cleanest way to do it.

Grinders are too aggressive and if the paint ain’t yet cured into a tough hard surface you could end up smearing it about and getting into a right mess.

A cup brush might also end up smearing it about too. 🤷‍♀️Dunno.

Good luck, it’s not something I’d look forward to doing. 

 

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The only thing Ive found that whizzes round and removes bitumen without just heating and smearing it back on again is a Tercoo. Actually does a really good job of removal but they are a bit dear and no good for corners as are a bit delicate.

My second choice would be as Bobbybass suggests, a multitool 

 

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