I had my 100S frame dipped (not acid but caustic) and I am glad I did. Put
in some extra drain holes and then put Waxoyl in the frame. I didn't put the
primer on for years as I had to remake the superstructure and rivet it on.
Quite different than a stock Healey. This time period allowed plenty of time
for excess chemical to leach out and be wiped away. The frame was a pleasure
to work on and no excess sand hit me in the face or the painter when air
pressure was applied to a corner. So the risk is chemical leaching after
primer/paint has been applied.