Following the steps in part 1, the results at this stage should be,
well… an ugly mess. Don’t fret. This is where the fun begins…
Generally speaking, I like to prime right over the raw, untouched
bondo and gap sealer before I sand. Personal preference I guess.
If you want to do some additional Bondo work, glazing putty and sanding,
before primer, go right ahead. It’s YOUR helmet.
Obviously, the white spots are low spots, whereas the primer is “middle”
and the pink is the bondo high spots.
For those new to surface prep, you want to sand down the high areas without
digging too much into the lower areas.
Since you are using anything from 40 to 100 grit to sand down the bondo,
it’s easy to tear into the plastic and mess things up quickly.
If you do gouge a chunk of plastic out, it’s not a huge problem.
You can mix up some Bondo, or if it’s a really bad chunk,
mix some plastic shavings in with some plastic weld and apply to the spot.
When you are done sanding, you should see smooth transitions from your surface
to the bondo. It’s okay to run your hand over the surface a few times.
Since you used a very rough grit to knock down the primer, you’ll want to
move up a few stages and get the heavy scratches out.
If you started with 40-60 grit, move up to 100/120, then 180/220, then 320.
If you started with 100/120, move up to 180/220, then 320.
If you want, you could sand with 400, but you’ll be wet-sanding with 400 soon anyways.
As you sand, you may want to, from time to time,
clean the surface with a tack rag and apply a fresh coat of primer.
Be careful not to apply too many coats of primer.
Wait about an hour after applying primer before sanding, no matter what the can says.
At this stage, between sandings you really only want to be applying a light
“dust coat”, otherwise you’ll develop problems later on from too many coats of primer.
After a few coats of primer, you may want to wet-sand the primer with 400 grit
sandpaper, and then wet-sand with 600 grit in order to start
smoothing things out for the color coat.
Personal Preference, as some wait to wet-sand after the first coat of the color.
In part 3 we’ll do final surface prep, color coat and weathering.