Stuck! Could use some advice re lacquering over Hammerite.

[television]

I have never got any problem anywhere for these paints. Its a main good clean and all pretty good with never any problem.

 

[om613]

I could be wrong but I suspect the issue is that with oil based paints it takes time for the VOCs (volatile Organic Compounds) to come out of the paint and until they do they can react with the next coat. If that coat is not oil based then it can float on the VOCs on the surface of the base coat and thats what causes the problems and reactions.

The VOC in Hammerite / Smootherite is Xylene, probably what's also in the Halfords 'cellulose' too.
Hammerite/ Smootherite both 'skin over' quickly, as per their IFU stating re-coat within 30 mins ... or else, 'ages', when it's hardened.

The difference between Hammerite and Smootherite is silicon which creates the 'hammered' pitting. If one finds an aged can of Hammerite that's gone off, peel off the top oily Si layer, and some thinners (Xylene) ... and you have Smootherite (and some lumps)

 

[Submariner1]

Imthi

I could be wrong but I suspect the issue is that with oil based paints it takes time for the VOCs (volatile Organic Compounds) to come out of the paint and until they do they can react with the next coat. If that coat is not oil based then it can float on the VOCs on the surface of the base coat and thats what causes the problems and reactions.

I think you are right GLK left it 4.5 hours and had no issues.
Interestingly mine seems to improve daily ... I kid you not so maybe its curing off underneath very very slowly.???

 

[Submariner1]

Bearing in mind my little "reaction issue" I very patiently left the Hammerite for 20 mins between coats (3 off). Looked lovely and smooth.
Again went to the hassle of leaving it with a 500w lamp playing bently on it so the air was just warmish for 4 hours, and then overnight. Looked really good.
So a 14 hour gap from last Hammerite to clear coat.
After the fist clear coat!
WTF

It went all crinkly !! Disaster.
Puzzled as I also painted the spring clips ( masked the Antirattle pads ) at the same time intervals and Bingo great result for me!

No reaction whatsoever ????

Was the paint a little thicker on the calliper I suspect so.
I also warmed the clearcoat over the hob when shaking it, so maybe it was a little too warm??

I am not winging, just documenting this saga, in the hope it helps other folks avoid my problems.

What to do now. :-/
Sadly I have one caliper painted OK. And the other three have hammerite hand painted, done when too cold so a bad finish needs rubbing down, so I am scared proper caliper paint might react.

The sensible thing would be to wait 3 day and rub this down and then do a very light coat of hammerite and wait 2 days. Then clearcoat. Thats a real pain doing it outside. Circa 3 days a caliper

Or waste the 3 cans of hammerite and buy calliper paint. Patch test to see if it reacts and follow that either rubbing it all off or overcoating with calliper paint.

Feeling a tad SAD!

 

[John Laidlaw]

Sorry to hear this , lot of work and some bad luck!
Think if it was me I'd bite the bullet and buy the calliper paint from Halfords ...
I'm trying to find the time to do my hubs and when eventually I do that's what I'm using ( not the faces obviously !)
Was going to do it at the same time as the pad change but just no time

 

[Submariner1]

Sorry to hear this , lot of work and some bad luck!
Think if it was me I'd bite the bullet and buy the calliper paint from Halfords ...
I'm trying to find the time to do my hubs and when eventually I do that's what I'm using ( not the faces obviously !)
Was going to do it at the same time as the pad change but just no time

Think you are right John.
For me it was a lot of work and looked great till the reaction. The masking is a freaking nightmare well t do it perfectly ... dont want paint on my piston seal rubbers or The sliding surfaces or pads.

I would bit the bullet in a heartbeat IF it wouldn't react with the hand painted hammerite ... thats on all of them.

I really do want the lacquered look. Both cosmeticslly but also as it sheds brake dust perfectly.

Question is how long to wait to rub this down. 24hrs ar a few days.

Think I may abort this till I have had my dust seal replaced by my Indy. As Ai dont want a calliper piston corroding.

Too many variables with this incompatible paint system. Could even be that the previous first laquer coat, was thinner and dried off delivering a sort of reaction proof barrier.

 

[Submariner1]

Spoke to Hammerite today.

After I hour too many solvents coming off. Reacts with acrylic.
After 4 hours less solvents coming off so OK , but a bit risky if the final curing process starts
After 12 hours you are into the final curing process, so lots of solvent residue starts to exude out of the paint

To be safe leave for 2 to 3 days, then no more solvents coming out, they even suggested washing it off.

The good news is I can overpaint a partially rubbed off surface with Hammerite and it will bond.