I have taken some pictures especially for this to show how we do this at work where we restore many classic cars and never had an issue with this technique.
VW Karmann Ghia
This one is not a full restoration, just a tidy up, but still gives the same idea.
All of the repair panels were welded in on the vehicle like so.
Around the repairs, the edge of filler/ paint was feathered out using a DA and p80 grade discs.
Has had repair panels all around the vehicle, here is filler applied and shaped around the front end.
The filler has the top knocked off with p40 on a block, then p80 then is lightly DA'd off with p180 before final stopper/filler etc
It is roughly masked just for primer.
Now for the etch. This is blown over the bare metal areas like so, even though some has gone onto the filler this is ok!
Once dry, high build primer was applied straight over the top.
The red/pink on the primer is the guide coat to show imperfections when flatted down, hope this helps you.
Heres some examples of the work done to show you wont have an issue.
Dan.
