Hammerite (small bubbles) Grrrrrr

Bought a rusted old winch bumper the other day.

Spent a day with a few wire wheels and Nitromors and got it back to bare metal.

Coated it in a marine grade rust converter as couldn't get every particle of rust off!

After that I primed it all in etch primer

I then painted it with Hammerite Smooth but god damn the air bubbles were a pain in the arse, just checked on it now and I run my hand over it and it feels full of bits!!

Going to have to rub it down a bit and try again, or maybe even try spraying it!

It was painted in the cold maybe about 5degrees but I warmed the bumper up with a heatgun first!

Anyone have any ideas?

why use etch primer, then hammerite?

Just to be on the safe side and it was back to bare metal

are they compatible?

take it back to bare and just use hammerite sounds like the paint has reacted to me. Hammerite hates fresh paint other than itself.

Didn't give it a thought, doesn't say anything about compatiblity on the tin, just says to prime with their own primer but I just guessed this was to push their own product

Do you think I would get away with a rub down tomorrow and another coat?

The bubbles aren't anything major, just when I run my hand down the bumper it feels like I've got a few specs of sand in my paint

Did you warm the paint?

Definetely sounds like a reaction. Also is it possible to keep some heat in the area you are painting rather than just pre-warming bar and until paint has fully hardened? Shame that happened after all your prep.

I didn't warm the paint but it was kept indoors under the bed so wasn't subject to cold conditions or anything.

Just don't want to waste my time with a second coat if it ends up the same.

Says on the back of the tin not to thin it down but what do you think?

musky81 said:

Definetely sounds like a reaction. Also is it possible to keep some heat in the area you are painting rather than just pre-warming bar and until paint has fully hardened? Shame that happened after all your prep.

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Yeah bit disheartening, especially in the cold!!

have fun rubbing it down again though as hammerite is a bastard, ive given up trying to rub it off my series chassis and getting it shot blasted

TD5power said:

have fun rubbing it down again though as hammerite is a bastard, ive given up trying to rub it off my series chassis and getting it shot blasted

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Ha I think I've had enough of rubbing down for a while, the bumper was originally powder coated and was a nightmare to rub off (even with the nitromors)

As much as it annoyed me that it bubbled, I've rather give it a quick rub down and another coat or a rub down and a dull clearcoat or something.

Just anything besides getting that damn wire wheel out again!

John506 said:

I didn't warm the paint but it was kept indoors under the bed so wasn't subject to cold conditions or anything.

Just don't want to waste my time with a second coat if it ends up the same.

Says on the back of the tin not to thin it down but what do you think?

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I spray everything. my Finnish is a bit hit and miss but still better than brush. I go direct from metal to hammerite rust treatment primer then thin down what ever hammerite I've chosen. Hammered finish is a bit crap via gun but rest are fine.

What ratio of hammerite to thinners do you use Snowman?

Also says on back of tin can only be mixed with Hammerite thinners, but again, just trying to push their own products?

Thinners are thinners right?

Yup I've had this too, Hammerite on top of red oxide primer gave me tiny bubbles which dried to leave a pimply effect. It's as if the paint's making gas as it dries. That was with Hammerite 'Straight to rust'. Mind you, I was doing the woodwork in my hall the other day with Dulux Satinwood and that bubbled and ran terribly. So I won't be using that on the Land Rover.

Mine is straight to rust also (had it lying about and didn't want to buy new paint).

What did you do in the end Brown, strip it off or a small rub and recoat?

tis a chemical reaction, the hammerite skins over, but also reacts with what's underneath, but there is nowhere for the gas to escape as the hammerite has skinned over, so it raises a little bubble

also, if you are putting a second coat of hammerite over the top of the first, make sure you follow the recommended time between coats for the same reason. I painted a mountain bike, which looked great after the first coat, was rock hard to touch, BUT after putting a second coat on, within hours looked like an explosion in an orange peel factory, could never get it back right after that.

I always thought the thinners are thinners too, but the hammerite thinners seem to smell different, and work better IMO

good luck though

John506 said:

Mine is straight to rust also (had it lying about and didn't want to buy new paint).

What did you do in the end Brown, strip it off or a small rub and recoat?

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Sad to say I just left it. It's on the bumper and rear crossmember so I'm not too bothered. With a second coat it was less conspicuous. If it had been somewhere more obvious at eye level I'd have sanded it down and tried again.

Thanks Optimus, I'm gonna give it a rub down in a minute and try a very thin coat of it with about 80:20 paint to thinner just to take some of the treacle consistency out of it.

Will let you know on the orange peel, hope not though as the front bumper is a main focal point

Should have just used the paint for what was intended, the chassis where it does not matter!!