Chassis black paint chipping off easily

[ProjectBobcat]

Hi all,

Looking for a bit of advice on where I;ve possibly gone wrong with painting some components with e-tech chassis black.

I've sand blasted back to bear metal, wiped over with thinners and then primed using red oxide primer, using a heat gun to gently warm the parts both before and after painting. Then after half an hour, brush painted with e-tech chassis black followed by a second coat within an hour, again using the heat gun to warm the parts. I left the painted parts for a couple for a couple of weeks in an unheated garage afterwards and now I've found that the slightest knock chips the paint off revealing the red oxide underneath. I don't think it'll last 5 minutes in the harsh environment underneath the car.

It seems that the chassis black hasnt adhered to the red oxide at all well. I tried contacting the manufacturer but no luck. It does say on the tin that its suitable for painting bare metal, but also that aluminium parts should be primed with a suitable primer, so I'd hope its capable of bonding to a primer based on that latter bit of info (all my parts are steel).

[ferny]

What brand of red oxide? I brushed some Screwfix branded stuff on my van sills and NOTHING will cover it. No matter what is used, it turns to dust and flakes off like dandruff.

[ProjectBobcat]

It's simoniz red oxide in spray can form, but the red oxide itself seems very durable. I've used the same stuff as a temporary measure where I've done some welding on another project, it's holding up well despite no top coat. I cant rule it out, but it isn't flakey like you've experienced.

[ant260z]

If your serious about protecting under body components properly I'd use this stuff Epoxy Mastic

It's not cheap, but you get what you pay for and it's as good as, if not better than powder coating.

[indyz12]

you will probably need to key the red oxide surface for the e-tech to properly stick. Most things suitable for bare metal fall into 2 categories - self etch or mechanical bond. I have a feeling its the mechanical bond type.

[ProjectBobcat]

Feb 24, 2022 18:19:12 GMT ant260z said:

If your serious about protecting under body components properly I'd use this stuff Epoxy Mastic

It's not cheap, but you get what you pay for and it's as good as, if not better than powder coating.

Thanks, it's comparable in price to the e-tech stuff so I'd be up for trying it instead.

[ProjectBobcat]

Feb 24, 2022 22:53:37 GMT indyz12 said:

you will probably need to key the red oxide surface for the e-tech to properly stick. Most things suitable for bare metal fall into 2 categories - self etch or mechanical bond. I have a feeling its the mechanical bond type.

Thanks, it might be the issue. The guidance suggesting aluminium should be primed first suggested otherwise, but perhaps there is a difference. I'll try keying the next part and see how it compares after letting it cure for a similar time.