Boiler Paint nightmare

[nigel jones 5Participant @nigeljones5]

I have completed my 7 1/4 Invicta. There is 2mm between frame and boiler so I decided that cleading and cladding was a non starter, only option is to paint it. So far I have sprayed it with exhaust paint – very dull and very soft, no resistance to scratching. Then I tried normal primer and paint – it blistered, finally PJ1. Good finish but when it was hot and bits dropped on it from the chimney they made a right mess of it. Any suggestions??

[nigel jones 5Participant @nigeljones5]

[Nick_GParticipant @nick_g]

Posted by fizzy on 27/04/2016 10:31:08:

ISo far I have sprayed it with exhaust paint – very dull and very soft, no resistance to scratching.

.

Some of those type of paints (no idea if this is one) have to become hot before they will cure properly.

No idea how hot. ……….. 'hot' is though.!

Nick

[pgk pgkParticipant @pgkpgk17461]

I've not tried it but stove paint below does come in a range of colours..

**LINK**

[John BaguleyParticipant @johnbaguley78655]

HI fizzy,

Have you tried Halfords high temperature enamel? I used it on my Helen Long smokebox and it's still good after 8 years. They do matt, satin, and gloss versions.

John

[nigel jones 5Participant @nigeljones5]

Hi JB – Thanks all

Does it need a primer – curing – top coat? Sent you an email but never got an answer

[nigel jones 5Participant @nigeljones5]

Brush or spray?

[Gordon WParticipant @gordonw]

Exhaust paint and stove paint does need to get hot, to hot to touch. I've used both types, some need a bit of "soaking" at high temp.

[norm nortonParticipant @normnorton75434]

Never use a primer under a high temperature paint – it was not designed to cope with the temperature. Remove EVERY TRACE old paint before recoating. Flat the surface with a 200-300 grit and rub with scouring powder (Vim or Ajax) and clean water. This will chemically activate the surface. Any solvent used to clean will leave a microscopic trace of oil.

Always try and use a spray finish, an airbrush is best but a basic aerosol can will work. As John says, many highish temperature enamels for car engines are fine. The problem with some of the wood stove paints is that they come out too grey and flat. Same problem with car exhaust paint.

Buy two or three different aerosols and try them on a old food tin (baked bean or coffee) that has been rubbed down and washed. There will be a difference in the sizes of spray nozzles and you can often swap them over. Practice on the food cans. Three coats is enough, a few hours between coats, first one very thin, final one thicker to ensure full wetting. Leave it 4 or 5 days to dry then light the fire for an hour, gentle blower only, to fully cure it.

Norm

Edited By norm norton on 28/04/2016 09:45:17

[nigel jones 5Participant @nigeljones5]

latest attempt – Strip all paint off using ethyl acetate (5 gallons in tank, 100% purity). Allow to air dry. Avoid handling any external surfaces and wear cotton gloves. Room temp 20 deg C, spraying PJ1 onto bare metal. Put too much on first time and it ran so straight back into solvent, washed off in seconds. Light coat, hanging from rafters, looks like good coverage. Propose 24 hrs between coats, 3 coats planned. I have seen ont web where people have baked the parts in an oven for 20 minutes @ 200 deg C, so I will try this as well! I can confirm that where the firebox sparks landed on the surface last time they made a right mess, leading me to thing that the paint wasn't completely cured at room temp even after 7 days. This is getting expensive!

[norm nortonParticipant @normnorton75434]

Hi Fiz

I looked up that PJ1 out of interest. It is very hight temperature resist (circa 800 degC) and used for motorcycle exhaust pipes. For some reason the manufacturer thinks it unsuitable for engines (car) or radiators. I think it will need a substantial heat cure. The manufacturers recommend three separate cycles with a final one at 340 degC.

Do let us know what the colour and finish is like after it is baked.

[Anonymous]

PJ1 used to be THE choice when repainting motorcycle engines but it unfortunately went the same elf and safety ingredients way of "proper" Hammerite a few years ago and is now nowhere near as good as it used to be.

[nigel jones 5Participant @nigeljones5]

Im not using the exhaust version, instead I picked the crank case type, good I think for 2-300 degrees. Anyone used it?

[norm nortonParticipant @normnorton75434]

Sorry, my mistake. I now see that they do several types all under the PJ1 brand.

[Author]

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