Tigerdude asked:
> Will electrolysis damage the lead sheathing on the iron?
Yes and no.... the answer depends on whether you think completely removing the nice white patina from the lead qualifies as damaging the lead.
Electrolysis removes metal oxide. Rust is oxide. Lead-Patina is oxide. (Brass patina is mostly copper oxide, etc.)
Electrolysis won't eat the lead itself (such as the cannon's rifling-groove marks on the sabot), but it will strip every bit of white lead-oxide patina off.
No, unfortunately, it doesn't help to try to apply a protective coating to the lead on your Sawyer artillery shell fragments to protect the patina during electrolysis. The only "coating" I ever was able to apply to protect the patina on a Hotchkiss lead sabot that actually turned out to work was to wrap it thickly in duct-tape. But after the electrolysis process finished, the duct-tape tended to try to physically pull off the patina when I unwrapped the tape from the sabot.
I know other people have tried coating the lead with wax. Some said it worked, some said it didn't... but everybody said getting the wax off the lead afterward tended to mess up the white patina.
Around 40 years ago I managed to find a few Sawyer shell fragments at the Port Hudson LA battlefield. Ultimately, I wound up meticulously cleaning the rust-crust off my own Sawyer frags "by hand." I used the claw-end tip of a hammer to chip off every bit of rust-crust, and then applied three light-to-moderate coats of Satin-finish Polyurethane.
I can't close this post without also saying Congratulations on your extremely rare civil war artillery find. Yeah, some will say those are just fragments... but they are from a shell whose rarity is rated at 8 on a scale of 1-to-10 (with 10 being rarest).
