Discussion
Nick's chassis paints are beginning to get something called 'solvent boil'. They were mixed by a former car sprayer, who is now one of his tutors, exactly as the instructions said. He is now back to bare metal on front outriggers. Should he scrape all the flaky paint off and hammerite it, or stone chip protect it? What is best?
Hi,
Think you will have to sand back all the affected areas to cure this, chances are it will be in other areas as well, I can think of a few things that will cause solvent boil / pop but not easy to figure out why, Best bet is to re do the chassis, Things to avoid next time are
Coats applied too thick.
Hardener and/or Thinner too fast.
Flash-off time between individual paint coats too short.
Flash-off time before baking too long.
Heat applied too close and too hot
When using a wet-on-wet system, too short a flash off between coats
Primer/ filler left to long before painting as it absorbs moisture
Alan
Think you will have to sand back all the affected areas to cure this, chances are it will be in other areas as well, I can think of a few things that will cause solvent boil / pop but not easy to figure out why, Best bet is to re do the chassis, Things to avoid next time are
Coats applied too thick.
Hardener and/or Thinner too fast.
Flash-off time between individual paint coats too short.
Flash-off time before baking too long.
Heat applied too close and too hot
When using a wet-on-wet system, too short a flash off between coats
Primer/ filler left to long before painting as it absorbs moisture
Alan
Alan Whitaker said:
Hi,
Think you will have to sand back all the affected areas to cure this, chances are it will be in other areas as well, I can think of a few things that will cause solvent boil / pop but not easy to figure out why, Best bet is to re do the chassis, Things to avoid next time are
Coats applied too thick.
Hardener and/or Thinner too fast.
Flash-off time between individual paint coats too short.
Flash-off time before baking too long.
Heat applied too close and too hot
When using a wet-on-wet system, too short a flash off between coats
Primer/ filler left to long before painting as it absorbs moisture
Alan
With all due respect guys, the tutor is an excellent painter, it's the product at fault here. They mixed it 50/50 paint/hardener and applied thinners as per instructions. It's an epoxy mastic so SHOULD remain slightly rubberised, but it doesn't. The chassis only seems to have suffered on the front outriggers, the rest seemed to be ok. Is sanding it all down and attacking the chassis with coarse grit paper the best best? Then applying something decent such as Hammerite? (which, by the way, is on the wishbones and trailing arms, and has proven to be immensely tough compared to the other paints!). Think you will have to sand back all the affected areas to cure this, chances are it will be in other areas as well, I can think of a few things that will cause solvent boil / pop but not easy to figure out why, Best bet is to re do the chassis, Things to avoid next time are
Coats applied too thick.
Hardener and/or Thinner too fast.
Flash-off time between individual paint coats too short.
Flash-off time before baking too long.
Heat applied too close and too hot
When using a wet-on-wet system, too short a flash off between coats
Primer/ filler left to long before painting as it absorbs moisture
Alan
Alan Whitaker said:
Hi,
If as you say it was mixed and put on right it must be the prep then, if you sand down and re paint you will need to do a test to make sure there is no reaction between the existing and next top coat you put on.
Alan
If he sands it back to bare metal, and then keys into that with some rough grit paper, will that be ok? If as you say it was mixed and put on right it must be the prep then, if you sand down and re paint you will need to do a test to make sure there is no reaction between the existing and next top coat you put on.
Alan
King Fisher said:
With all due respect guys, the tutor is an excellent painter, it's the product at fault here. They mixed it 50/50 paint/hardener and applied thinners as per instructions...
In that case, as well as asking the painter "WTF did you do to my paint?" I'd be asking the suppliers "WTF is this cr@p you sold me?". Either there's a problem with the paint, or it isn't suitable for that situation, or it wasn't applied correctly. The supplier and the painter between them ought to be able to work out what went wrong.GreenV8S said:
In that case, as well as asking the painter "WTF did you do to my paint?" I'd be asking the suppliers "WTF is this cr@p you sold me?". Either there's a problem with the paint, or it isn't suitable for that situation, or it wasn't applied correctly. The supplier and the painter between them ought to be able to work out what went wrong.
He did ring the paint supplier, and they told him he'd applied it correctly. The thing about this paint was that you mixed the entire tin of paint with the entire tin of hardener, and added the thinners. The problem was, if you put lots of thinners in and applied a thin coat, whilst you were waiting for that coat to dry and apply another, the paint would harden off in its paint tub and become a rubbery gloop, so the only option was to put it all on in one go. In hindsight, maybe he should have used a little bit of paint and a little bit of hardener at a time, but it's quite hard to measure a perfect ratio when the paint and hardener are both the consistency of pig s**t. The worrying thing is, that the red oxide he also applied beforehand is also coming off on the outriggers. He also believes someone has jacked the car up on the outriggers, and not applied a rubber pad to the metal jack, resulting in the paints being pulled off, as the rest of the chassis, which hasn't been subject to any trauma, is ok.
His plan is to sand it back to bear metal, key into the metal with some grit paper, or a wire brush on a grinder, and then paint over it. Now, should he use the red oxide/hammerite combo he used on his wishbones (which has proven to be extremely tough), just hammerite on its own, or should he use something like stone chip paint?
Thanks in advance.
King Fisher said:
The worrying thing is, that the red oxide he also applied beforehand is also coming off on the outriggers.
I suspect that there is your problem. I have used epoxy mastic chassis paints myself and they are pretty much bullet proof if applied correctly. The idea is to put the epoxy straight on the metal. Old style red oxide primer has far inferior adhesion and is most likely undermining the epoxy. Over time it's probably reacting with the epoxy and causing the solvent popping and lack of adhesion.I thought you had an expert paint man? If he can't cope with mixing the epoxy in useable quantities, well... Try warming the tins in a bucket of hot water. Then it will pour out in measurable quantities much easier.
Hammerite is very poor in high impact areas. Looks nice, but once it goes hard it becomes brittle and chips off very easily.
I don't know if you guys have ever come across this product before:
http://www.plastidip.co.uk/eStore/index.cfm?type=C...
but I have used it in many industrial applications where metal would be subjected to corrosion. It really is excellent stuff, sticks like s
t to a blanket, is tough and lasts for years! It has a lovely smooth plastic like finish too.
I'll be putting it on my Tuscan Challenge car chassis over the winter.
http://www.plastidip.co.uk/eStore/index.cfm?type=C...
but I have used it in many industrial applications where metal would be subjected to corrosion. It really is excellent stuff, sticks like s
t to a blanket, is tough and lasts for years! It has a lovely smooth plastic like finish too.I'll be putting it on my Tuscan Challenge car chassis over the winter.
jwoffshore said:
I suspect that there is your problem. I have used epoxy mastic chassis paints myself and they are pretty much bullet proof if applied correctly. The idea is to put the epoxy straight on the metal. Old style red oxide primer has far inferior adhesion and is most likely undermining the epoxy. Over time it's probably reacting with the epoxy and causing the solvent popping and lack of adhesion.
I thought you had an expert paint man? If he can't cope with mixing the epoxy in useable quantities, well... Try warming the tins in a bucket of hot water. Then it will pour out in measurable quantities much easier.
Hammerite is very poor in high impact areas. Looks nice, but once it goes hard it becomes brittle and chips off very easily.
Nick was advised by a TVR service centre to prime the metal with red oxide first? It's only cracked in one area, so he can rub back to bear metal and do it again in the problem areas.I thought you had an expert paint man? If he can't cope with mixing the epoxy in useable quantities, well... Try warming the tins in a bucket of hot water. Then it will pour out in measurable quantities much easier.
Hammerite is very poor in high impact areas. Looks nice, but once it goes hard it becomes brittle and chips off very easily.
I'd be inclined to disagree with you on the olde hammerite, it's proven to be immensely tough on the wishbones; they had to hammer the wishbones back into the chassis lugs, due to the polybushes being a bit too fat, and the hammerite stood up to it fine with no cracking.
jwoffshore said:
Well, obviously my advice and experience is just a load of bks then! But try reading the technical data sheet for the epoxy mastic first.
He may just lift the body partially, clean it all down, and paint it again with the epoxy heated up and the metal thoroughly roughed up.ks then! But try reading the technical data sheet for the epoxy mastic first.Gassing Station | S Series | Top of Page | What's New | My Stuff