Painting epoxy primer over old original paint

[Arin]

As the title says, I'm going to repaint my engine bay, the original factory paint is good.

Can I use green scotchbrite pads to scuff the surface before applying epoxy primer, the reason i ask, is because the engine bay is not easy to sand with paper and the pads are more maneuverable into small nooks and crannies.

is the grit enough?

i believe green equates to about 320 (any bare metal will be prepped with a coarser grade sandpaper - 120).


but to scuff original paint , is green pads enough for the epoxy primer to stick?

thanks for the help

 

[Swift&Bold]

Epoxy primer needs to be applied to bear metal prepared to SP2 to be totally effective

 

[Arin]

sorry, what is sp2? I thought epoxy primer could be applied over old paint!?

 

[norsa]

Cant say I've heard of bear metal or SP2. Not sure what grade green is but the standards are red and gray. Red will be perfect for your engine bay.
Nick

 

[zx9]

sorry, what is sp2? I thought epoxy primer could be applied over old paint!?

If the old paint and metal behind it is good you can use epoxy as an isolator so yes you can, obviously bare metal is best but it is not always practical / economic to go to all the effort.

Edit: added word you

 

[steveo3002]

yep red scotch pad is fine , and obviously the epoxy and new paint will only be as good as whats underneath , so all long as it truly is sound and good condition then fine , roar anything suspect back to bare clean metal

 

[Swift&Bold]

SP2 is the industry standard for metal preparation by machine, e.g shotblasting and abrasives.
You can apply it over whatever you want but for it to have any chance of being totally effective it needs to go back to bare metal as advised by the various manufacturers. If in a years time the metal underneath starts degenerating and you try to play the 'under guarantee' card they will not entertain it without the necessary preparation.

http://www.blastal.com/images/SSPC_Chart.pdf

 

[norsa]

I am obliged. I would not advocate shot blasting car body panels though. Ever

 

[langy]

SP2 is the industry standard for metal preparation by machine, e.g shotblasting and abrasives.
You can apply it over whatever you want but for it to have any chance of being totally effective it needs to go back to bare metal as advised by the various manufacturers. If in a years time the metal underneath starts degenerating and you try to play the 'under guarantee' card they will not entertain it without the necessary preparation.

http://www.blastal.com/images/SSPC_Chart.pdf

I agree that it should be used on bare metal but for years people have been using it as an isolator coat without any problems, it's more important in a specific application, on cars it's fine.
I once split a drip on a windscreen, it was a devil of a job to remove as it not only mechanically adheres but chemically as well.
As for shot blasting car panels they won't be very straight after

 

[Swift&Bold]

Hehe......Yeah, I should've made that clear regarding shotblasting