Questions by R. B. Kаvinoky, Bechtel Corporation, San Francisco, California:
Did electrical resistances measured after one minute, 24 and 48 hours immersion offer as good correlation with the observed durability of the coatings as the resistances measured after several days or weeks immersion? Also, have the studies mentioned been extended to include coatings applied over irregular surfaces such as welds? If so, did such tests result in the elimination of coatings which might have appeared acceptable when examined on smooth steel plates?
Our own experience tends to confirm the merit of the electrical resistance test described, but we suggest that equipment capable of measuring higher resistances at lower voltages might extend the usefulness of the method.
Replies by R. W. Flournoy:
Electrical resistance measurements at one minute, 24, and 48 hours are sufficient to determine whether coatings are poor because of porosity, pinholes, and holidays. Coatings which are relatively free...
