Capstrips have to have holes debured, and scotch brite. After several cleanings they are ready for the acid bath. The felt markings will not survive the acid. I have some alodine markings that should survive. Just in case I place a placed a couple of rivets to align the match drill sets (front and back). I then sand a unique pattern in the end while taking a picture allowing the set to be identified as a backup plan. The trough for the etch alodine process was made for the Main Spar capstrips. I already had the parts but it still takes time to level the split 4 inch pipe. One trough is water,one trough is acid,and the final trough is alodine. There are other ways of alodining capstrips, this is just my preference.