by Ty Grabowski
As a technology developer and lifelong scientific diver involved in crime scene preservation and artifact preservation I have on several times come across the problem of preserving bronze that has corroded or diseased. It appears I may have found a solution for bronze disease. Objects of bronze that are afflicted when polished or cleaned chemically or physically always continue to degrade or corrode. I suspect this is caused by physical changes to the metal on a microscopic level. Moisture and oxygen as well a nitrogen in the metal and surrounding environments. The solution or treatment that appears thus far to be the best treatment follows.
I used electricity and commercially available degrease agent to clean the objects, then rinsed each artifact in distilled water to remove any chemical residue. I removed the object from the water and placed it directly in a bath of medical grade acetone to remove any remaining moisture from the metal. Once removed from this bath the acetone remaining on the object quickly evaporates leaving only .0001 percent trace residue. I then grounded the artifact to the electronic plating machine and plated it with pure nickel until the object was covered with a microscopic layer of nickel. I then plated the nickle surface with a layer of fresh bronze plate. The layer of nickel seals the metal from oxygen and nitrogen at a microscopic level and prevents any further corrosion of the original metal while the layer of fresh bronze serves to protect the nickel and restore the artifact to its original color.
Nickel is the only metal that can be plated directly to copper. Bronze is arsenic enriched copper with at least .04 percent arsenic, though this process works on antique brass (copper/zinc) or modern brass (copper/ tin). Once the object is plated with nickel it can be plated with chrome, gold, zinc, copper, silver, bronze, platinum, radium, or zirconium.
All of these would likely work. a layer of gold or zirconium would provide even greater protection though they are more costly.
Done properly it is not physically possible to tell on sight that the object has been treated. The plating is thin enough for scratches and fine details to show through. I.e., if we took two identical gold coins and plated one with nickel then with gold and left the other coin alone. with out scratching the coins or weighing them—no one would be able to tell them apart.
I have thus far treated numerous test pieces including severely afflicted bronze swords from China that spent hundreds of years in salt water, several Ming dynasty bronze statues, and numerous coins that where buried or lost in soil. Two years after treatment I am still finding no signs of further bronze disease.
All materials used are affordable enough that a sword can be treated for around 25.00 dollars and the reusable plating machine required runs around 2,500 dollars. A small price to pay to save something like the liberty bell!
A mysterious wasting event of numerous species of sea stars is currently occurring in parts of Central California. Scientists at UC Santa Cruz have created a couple pages to track the event. They are encouraging divers to fill out the Sea Star Disease Tracking log if you notice the presence OR absence of wasting disease, and include the GPS coordinates.
Interested readers and divers may also be interested in my old friend Chris Mah’s recent post on the phenomenon.
Reef Check Foundation is searching for a Southern California Volunteer Coordinator. This position may be a perfect fit for a person with extensive California diving experience who wants to do research diving and has a passion for working with volunteers. We are looking for someone who is highly motivated with strong leadership skills and, ideally, has a background in marine biology. Preference is given to candidates that are professional dive leaders.
Also see here.