Conservation of a gun carriage

The guns recovered from the Mary Rose are highly significant. They include some of the earliest cast bronze muzzle loading guns made in England, as well as a suite of wrought iron breech loaders. Finding these together has completely revised our understanding of the use and longevity of wrought iron guns.

Over the course of the eleven-year excavation of the Mary Rose hull, from her discovery in 1971 until her lifting in 1982, an unprecedented arrangement of 16^th century guns were found, most of them still on their wooden carriages. These carriages and others found on shipwrecks are, with a few exceptions, the only evidence of carriages. The ones found with the Mary Rose are among some of the earliest examples.

On the upper deck a bronze muzzle-loading gun called a culverin was found; this particular culverin would have been loaded with iron shot five inches in diameter. It was found on its carriage, the muzzle pointing out of an unlidded gun port and with a shot still loaded in the barrel. One of my jobs as a Conservation Intern at the Mary Rose Trust in the summer of 2024 was to, with the help of another intern, clean and conserve the gun carriage.

Gun in position in the Main Deck context gallery

The carriage had previously been treated with Polyethylene Glycol (PEG), an inert bulking agent that is used in everyday products like toothpaste. This replaces the water within the structure of the wood and reduces the shrinkage as it is dries. But excess PEG can be left on the surface of the object so removing this was our first task. We started with the two cheek pieces, working on one each and using dental tools, scalpels, brushes and a vacuum. The aim was to take the surface layer of PEG off without damaging the wood, but this proved harder than we thought, as the wood was spongy in places. Iron ions from the fixings used to hold the wooden pieces in place had also changed the structure of the wood and caused a black powder to form known as iron sulphide. Iron sulphides can convert into salt efflorescence or sulfuric acid which can result in chemical and physical damage, as the process leads to degradation of the cellular structure weakening the wood. The plan was to remove as much of the iron sulphides as possible without compromising the structure of the object.

Slowly, we moved across the surface removing the PEG until we were both happy our pieces were as clean as they could be. Then we washed the surface using a very small amount of water on a brush and dabbed with a cloth. This removed any PEG left in the cracks and took any excess dirt off the cheeks. The final stage was to recoat the surface with a layer of PEG to seal and protect the wood.

This process will be repeated across each piece of the gun carriage and finally the carriage will be reassembled and reunited with its gun in the museum.

The conservation of an object is an ongoing process, so despite the fact the carriage had been treated before, more work was needed. This is because we cannot stop the deterioration process only slow it down. Nothing is designed to last forever, so our job as conservators is to care for these objects the best we can so that future generations can appreciate and enjoy them for as long as possible.