Savannah River Cannon Cluster Site

Cannon Conservation

At CRL, all cannon were photographed and measured, and this documentation was repeated throughout the conservation process; additionally, all cannon were scanned with a FaroArm, which allowed for an accurate 3D model to be made for each. After documentation, the first step in conservation was to remove the thick layer of concretion that had accumulated.

Notably, 12 of the cannon had a wood plug, called a tampion, in place at the muzzle, nine of which were mostly intact. This was common for cannon used on ships, in order to prevent water from getting into the bore and damaging the gunpowder in loaded guns. The intact tampions were also beneficial for conservators because they both prevented the formation of concretion in the bore (which can be difficult to remove in such long, enclosed spaces) and protected the organic contents from being damaged by erosion or pests. Conservators unloaded the cannon, noting the distance from the muzzle of each artifact removed. Most cannon had a similar loading pattern: tampion, junk wad, two cannon balls, junk wad, powder cartridge. The contents were labeled and separated into groups for different treatments.

All cannon were conserved using electrolytic reduction; they were sealed with a combination of tannic acid, microcrystalline wax, and black matte alkyd paint.

Cannon Identification

All 17 cannon sent to CRL have been identified as muzzle-loading smooth-bore cast iron 6-pounder guns. Once the concretion layers were removed, conservators could view details that could help narrow down where and when they were manufactured. There are four distinct styles present in the collection:

• Types 1 and 2: The three longest guns. Type 2 guns are etched with weight measurements near the vents and have markings on the trunnions, but no marks indicate a foundry or country of origin.
• Types 3 and 4: Short guns, primarily differentiated by presence of muzzle flare (Type 4 has a more prominent muzzle flare). Notably, all 14 of these guns were cast with two vent platforms, 180 degrees apart on the breech end. There are also inconsistencies in the casting of these cannon, such as trunnions that are not parallel and uncentered bores.

Many of the cannon had etched or embossed markings on them. To preserve them, conservators made silicone rubber molds, then epoxy casts. If the marks became clearer as treatment progressed, conservators made another mold. The most identifiable markings were:

• Conjoined HP: found near the vent of 8 of the short cannon. Likely to be the foundry marking, but the foundry is yet to be identified.
• 11’2”7: marking near vent of Style 2, indicating the original casting weight of the two guns (11 British hundredweight, two quarter-hundredweight, and seven additional pounds, for a total of 1,295 lbs).

Ammunition

In addition to the 27 six-pound balls removed from the cannon, 12 pieces of ammunition from the Cannon Cluster Site were sent to CRL, all of which matched the diameter of the cannon bores: two balls, four bar shot with hemispherical ends, three bar shot with cylindrical ends (hammer shot) one bar shot with spherical ends, and two expanding bar shot with hemispherical ends. While cannon balls were more effective in damaging the hull of a ship or fortifications on land, bar shot were largely used to disable sails and rigging.

Like the cannon, conservators first used air scribes to remove the concretion from the ammunition, then conserved them using electrolytic reduction; they were sealed with tannic acid and microcrystalline wax. One of the pieces of expanding bar shot was in a very good state of preservation, and after conservation, the two arms can expand and compress.

Junk Wads and Tampions

Nine of the 17 cannon contained relatively intact tampions; these bores were sealed well enough that the junk wads (bundles of rope) and powder cartridges within remained relatively intact. Most of the rear junk wads, further protected by the cannon balls, have retained their original shape. The organic materials in the bores with fragmentary or no tampions did not survive as well.

Over time, all of the organic material inside the bore had turned black from the presence of gunpowder mixing with the water that had made it into the bore, so the first step in conservation was rinsing, followed by chelation to reduce the iron residue that could interfere with treatment chemicals. The wood and rope were pre-treated with polyethylene glycol (PEG) in water, then freeze dried.

Eight of the cannon vents contained fragments of the wicks that would have been used to ignite the gunpowder. Because of their size (the largest is about 2cm in length) and fragility, conservators chose to limit their time in wet treatment: they were carefully rinsed, then slowly dried in a controlled environment.

Powder Cartridges

14 of the 17 cannon contained powder cartridges, nine of which are mostly intact, or have enough fragments that together would closely match the size of an intact cartridge. They were originally assumed to be a textile because: they survived in a damp environment for so long, the existence of cannon treatises recommending various textiles dating to at least the 17th century, and the presence of what was thought to be a warp and weft pattern in cleaner patches of the cartridges. Conservators discovered, once the gunpowder had been mostly rinsed out of the first cartridges, the cartridges were in fact made of paper.

The intact cartridges were in an impressive state of preservation: during pre-treatment photography, conservators were able to unfold the cartridges under the camera so that the folding pattern could potentially be replicated on models.

After photography–and removal of any large clumps of gunpowder–conservators rinsed the cartridges in water, using a stiff mesh (window screen) to support the paper. Under the direction of a conservator who specializes in paper, CRL conservators then dried the paper between sheets of blotting paper. Once dry, the remaining gunpowder was removed using eraser dust, revealing the more natural (though iron-stained) color beneath the black powder. The paper is currently under the care of a paper conservator, who is using wet cleaning methods to un-wrinkle the paper and perform repairs.

External Resources

Carpenter, Alyssa. 2025. Conservation and Artifact Analysis of 17 Cannon: Cannon Cluster Site 9CH1552 Savannah, Georgia. Master’s thesis, Department of Anthropology, Texas A&M University, College Station, TX.

James, Stephen R., William Wilson, and Gordon P. Watts. 2022. Submerged Cultural Resources Data Recovery of Site 38JA1178 and Artifact Recovery of Site 9CH1522 Savannah Harbor Expansion Project Savannah, Georgia. Report to U.S. Army Corps of Engineers Jacksonville District, Florida, from Commonwealth Heritage Group, Inc., Memphis, Tennessee.