This week we’re taking a detour from your usual Turret updates for some Dry Ice Blasting! After quite a bit of research we figured out the best settings for Dry Ice Blasting on cast iron (previously we’ve only treated wrought iron with this method) and our first application is for the treatment of a pair of British guns from The Revolutionary War. These guns were part of the armament on transport vessels supporting General Lord Cornwallis’s British army during the Yorktown Campaign. The guns were sunk when Cornwallis ordered the transport vessels to be sunk as obstructions, to prevent the nearby French fleet from coming to the aid of General George Washington’s troops.
The guns were raised from the York River in 1934 through a joint effort by The Mariners’ Museum, National Park Service, and Newport News Shipyard, and they’ve lived happily on and off display at both Yorktown and The Mariners’ Museum. But as you can see, they need a little TLC before they can be displayed again.
When they were last treated, a protective coating of paint was applied to the guns, which worked for a number of years to prevent corrosion, but has recently started to peel off of the surface and corrosion has formed where the paint failed. The old paint now has to be removed because it can trap salts within the iron. I’m sure many of you remember from previous posts that salts are the bane of any object (and conservator’s) existence, and will cause metals to corrode. Removing the paint will allow the salts to flow freely out of the guns during desalination.
We applied a solvent to the paint to soften it, and then used Dry Ice Blasting to quickly remove it.
The blasting treatment was so much fun and worked even better than I’d imagined. In only a matter of hours I was able to remove the paint and active corrosion from the surface. You can really see the difference!
Now that I’ve had all my fun Dry Ice Blasting this week, the guns are ready for Electrolytic Reduction and Desalination. You may see them again in a month or two for another round of Dry Ice Blasting, so stay tuned!