In some places, it’s completely legal to search for and recover artifacts from shipwrecks. Once you get these items to the surface, it’s important to care for them properly, whether you plan to keep them for your own collection or loan them to a local museum or dive shop for public display.
What Air Contact Does to Artifacts
Many items that have been submerged for a long time begin to oxidize (break down) immediately upon contact with open air. This mostly applies to reactive materials including steel and other metals, which will start rusting as soon as they reach the surface and dry off. To prevent your artifacts from breaking down prematurely, soak them in a tub of water until you can begin the preservation process.
Long-term Soaking
Many items, particularly metal ones, need to be soaked in fresh water for about a month to allow all the salt and chlorides to exit the artifact. Use a large plastic bin to soak your artifacts, and change the water as it becomes cloudy. Professional preservation experts sometimes skip this step in favor of a process known as electrolysis, in which an electric current is passed through an electrolyte solution. This is a fairly complicated procedure, however there are many great sources describing how to set up for and conduct electrolysis.
Silver, gold, tin, and lead typically require less soaking, although you may need to scrub them or gently pick away tarnished or corroded areas. In some cases, picking or excessive scrubbing will damage an artifact; depending on the item, you may consider taking it to a jeweler for professional cleaning and preservation.
If you have a porcelain, pottery, or china artifact, don’t use electrolysis. Instead, give the item a good soak, leaving it submerged in fresh water for about eight weeks and changing the water daily. You can also soak deeply stained china in lemon juice, which helps to eliminate salt and is not likely to harm any gold trim on the items you are preserving. Soak glass bottles for just a few days before moving forward with preservation. Some very old bottles will crack after drying out – this usually occurs when glass dates back to the 1700s or earlier.
Leather items need to be soaked for up to two weeks before preservation. Wood items need to be soaked for weeks or even months, depending on their age, size, and thickness. Both leather and wood will degrade rapidly if not soaked before preservation.
Preservation Techniques
Preservation techniques vary depending on the item you have collected. Glass, precious metals, china, and glazed pottery often respond well to long-term soaking and careful display. Some divers take the extra step of using a clear polyethylene spray to preserve items, however it is vital that they are completely dry before this step is taken.
Because wood and leather are porous, organic materials and time underwater completely changes their cellular makeup, they must be impregnated with polyethylene glycol, which helps to keep cracking and shrinkage to a minimum. After soaking long-term, submerge them in a bath of polyethylene glycol long-term. Small items such as boot soles or deadeyes take about six months to fully impregnate; larger artifacts can take years to preserve.
If you’ve found something you’d like to preserve but are not capable of taking care of it on your own, contact a local maritime museum for assistance. Not only will they have the facilities, chemicals, and storage space required for preservation, they will appreciate the opportunity to share your finds with the public. Serious about treasure hunting and artifact preservation? There are many wonderful books on the topic. Invest in one and be sure to follow step-by-step instructions for preservation to the letter. This will ensure that the treasures you have found will be enjoyed for many years to come.