Overpainting Gravitex

[Paulfc]

As I work around the underside of the car I use Gravitex on wheel arches, chassis etc. overpainting whatever is there having first cleaned away oil, grease and the like. The car doesn’t get a huge amount of use and this approach suits my driving regime and, I have to say, I find Gravitex really good. It does dry matt black.

I have some minor damage to the black stonechip that’s exposed bare metal on the lower sills which I may cover with Gravitex. Can anyone please advise me if I do this, and maybe also the entire under sill, can I overpaint it, and with what, to achieve a gloss finish? 
 

Thanks

[chrishawley]

Opinions may vary; but here's my experience....

Overpainting: Gravitex or indeed another other non-waxy stone chip protect can be overpainted with pretty much anything provided it is absolutely fully cured and this takes a long time at winter ambient temperatures. The consequence of overpainting a not-fully-dried stonechip can be a crazed sticky mess as the thinners in the overcoat 'wake up' the stone chip.

Two pack paint over stone chip gives a gloss surface which can be made more so by going over with primer first. Primer will also help with colour match/blend esp. if the finishing colour is a light shade. Single packs (e.g. rattle cans) might need several coats to get a gloss surface. I've  found brushable enamel (from Paintman) to work well on less visible areas like wheel arches and undersides of sills.  

Application: Applying stone chip over previous stone chip or body colour is fine provided the area is degreased and keyed up. But it would do just to confirm that the previous coating is not a bituminous or waxy underseal. The instructions for Gravitex say it can be applied to bare steel but that seems a bit optimistic and it's probably better that any bare metal recieves a primer first (etch, bondaprimer or whatever is one's favourite).

Pretty much any coating adheres better if the base is scrupulously degreased and keyed up and I'd give emphasis to that with stone chip as much as anything else.

[dougbgt6]

Yes fully cured, I use salt, sugar and dill. It does smell a bit so overpainting is a good idea.

Doug

 

[Paulfc]

Hi Chris,

Thank you for the advice.

Paul