conor1n
Member
- Messages
- 556
- Location
- London/Ireland
Hello,
Interested in peoples thoughts here.
I am of the understanding that when it comes to adhesion of paint/primer etc .. shot blasted steel is best. But what do you do when you can't blast, for various reasons.
It's too easy to clean up metal with a wire wheel on some kind of grinder .. the steel comes out super clean but is "polished" and stuff won't adhere to it. In the past for parts here and there, I just lash on some etch primer and hope it's fine as you get chemical adhesion via the etch.
But what is a better way?
* Sand paper seems hit and miss when it comes to crevices etc.
* If i'm not using etch primer, I will sometimes use a maroon scuff pad. Is this or green ok?
* I have also noticed that putting a wire brush on a drill (low speed) seems to scuff up the steel good and not polish like the high speed tools.
FWIW...
When I did the underside of the Clio as seen below .. the factory underbody was kept in tact.. but the bare steel was prepared using high speed brushing .. so it's all effectively polished. If you see the rocker panels on each side, the bare steel there... well, when I was prepping the car for paint, the epoxy mastic stared peeling off there with my masking tape. Which was quite a painful discovery tbh.
I now believe that if I was to go around with some masking tape on any of the polished areas below, then the mastic would come away in sheets as described. I'm going to continue to build the car, and can revisit the underside coating later on.
Interested in peoples thoughts here.
I am of the understanding that when it comes to adhesion of paint/primer etc .. shot blasted steel is best. But what do you do when you can't blast, for various reasons.
It's too easy to clean up metal with a wire wheel on some kind of grinder .. the steel comes out super clean but is "polished" and stuff won't adhere to it. In the past for parts here and there, I just lash on some etch primer and hope it's fine as you get chemical adhesion via the etch.
But what is a better way?
* Sand paper seems hit and miss when it comes to crevices etc.
* If i'm not using etch primer, I will sometimes use a maroon scuff pad. Is this or green ok?
* I have also noticed that putting a wire brush on a drill (low speed) seems to scuff up the steel good and not polish like the high speed tools.
FWIW...
When I did the underside of the Clio as seen below .. the factory underbody was kept in tact.. but the bare steel was prepared using high speed brushing .. so it's all effectively polished. If you see the rocker panels on each side, the bare steel there... well, when I was prepping the car for paint, the epoxy mastic stared peeling off there with my masking tape. Which was quite a painful discovery tbh.
I now believe that if I was to go around with some masking tape on any of the polished areas below, then the mastic would come away in sheets as described. I'm going to continue to build the car, and can revisit the underside coating later on.