Eighteen years ago: Covering the curating of SS Central America treasure

One of the biggest stories Coin World has covered in its long history is the saga of the SS Central America. Our first article appeared in 1989 and it would be followed by dozens of others. The 2014 recovery of new treasure resurrected the story and collectors have been eagerly awaiting the sale of the new coins, gold bars, gold dust and other treasure recovered from the wreck site. The hobby will get its first look at the new treasure at the Feb. 22 to 24 at the Long Beach Coin, Currency, Stamp & Sports Collectible Expo in California when the "Ship of Gold" is resurrected with the new treasure.

During the 1990s, much of our news coverage focused on the legal battle to determine ownership of the treasure. Insurance companies that had paid off claims for the gold lost in the 1857 shipwreck claimed the treasure belonged to them, something that the salvors strongly disputed. Ultimately, most of the treasure went to the salvors and only a small portion, around 8 percent, was award to the insurance firms.

When the legal battles ended and the numismatic community began learning details about what had been recovered, attention was turned to the condition of the material. In the summer of 2000, I went to the Long Beach Expo to meet with Robert Evans, chief scientist of the Columbus-America Discovery Group, the Ohio-based firm that found the shipwreck and recovered the gold.

What follows is my news article from the July 3, 2000, issue of
Coin World reporting on what Evans showed me. The article has not been updated, other than minor formatting. And it is clear that the market has embraced the coins and ingots recovered from the shipwreck, despite some initial skepticism in 2000 about the coins being curated. The article has not previously appeared online:

The first thing you notice is the stink — the smell of rotten eggs.

From this inglorious and odoriferous beginning comes the sweet smell of success and a beautiful end — the SS Central America’s  gold coins freed of 14 decades of encrusted rust and limestone. And, according to the salvage expedition's chief scientist and historian, without affecting the actual gold surfaces of the coins one iota.

Robert Evans is the Ohio geologist, paleontologist and amateur historian who was a central figure in the Columbus-America Discovery Group, which found the shipwreck, located in the Atlantic Ocean off the Carolina coast. He is also the man who devised the process for removing more than a century's worth of the sea bottom's biological detritus from the tons of gold bars and coins recovered from the wreck site.

Coin World got a hobby-exclusive look at the process being used to separate decades of incrustration from the shipwreck gold, during a visit with Evans behind the SS Central America display at the June 8-11 Long Beach (Calif.) Coin and Collectibles Expo. Evans took Coin World through the process systematically with two 1856-S Coronet $20 double eagles, allowing photography of each step and explaining what was happening to the coins and the materials encrusting them.

The process being used is at the heart of controversy, at least in the eyes of its detractors. Many of them label it cleaning and therefore forbidden under the old school of thought that a true collector never cleans his coins. How, they ask, can a company like Professional Coin Grading Service grade and encapsulate the Central America coins when they've been cleaned? Shouldn't they have been returned in "body bags"? the detractors ask. Is this a case of the "big boys" getting preferential treatment from PCGS?

To Evans, the process is a means of uncovering the true beauty of the coins, hidden not by a discoloration or toning of the coins themselves, but by physical incrustations generated by several biological processes. Evans does not like to use the word "cleaning" to describe what he has been doing to the coins, because of all the negative connotations improper cleaning techniques engender. He prefers to call the process "curating.

What to call the process is more than a simple exercise in semantics. While it's true that what is done to the coins falls under a dictionary definition of cleaning, Evans is adamant that the coins themselves are not changed by the process. He insists that what he does differs from the negative forms of cleaning that involve physical or chemical changes to the coins themselves.
That's why he was eager to explain to Coin World, and its readers, what is being done to the 
Central America gold.

What they found

The "curating" of the coins was made necessary by their state when recovered from the wreck site. When the Nemo — the Columbus-America Discovery Group's robotic submersible used to search the wreck site and recover artifacts from the ocean floor — first found the gold, it "found a mysterious tower of 300 double eagle gold pieces standing alone unsupported," wrote CADG founder Tommy Thompson in his book, America's Lost Treasure. "The coins had been cemented together by a light glaze of sea salts and rust, a miniature, golden, organic architecture resisting the constant push of gentle seafloor currents."

While gold is one of the least reactive of metals (seawater alone can destroy silver coins given enough time), biological activity surrounding the wreck site left its mark, however temporary, on the coins. The coins were encrusted with varying thicknesses of rust, limestone and other minerals. The rust was from the ship's iron engine and boilers, with the deposits on the coins due to iron-fixing bacteria in the surrounding water. The limestone, or calcium carbonate, was composed from the shells of dead plankton on the seabed.

The gold was encrusted with a particular form of iron rust called goethite, or alpha-FeO(OH). The SS Central America carried 750 tons of iron aboard, including its engines and boilers. After the ship sank in a September 1857 hurricane, the natural processes that cause iron oxidation began. This process was aided by iron-fixing bacteria, which metabolize the iron; a form of the iron ended up on everything in the shipwreck's vicinity, including the coal used to power the steamship and the gold coins and bars for which the treasure salvors spent millions seeking and recovering.

Other materials were also found attached to the coins and bars, including wood fragments (the wood was slowly rotting away, food for bacteria and wood-boring worms). Most of the wood used in the crates and boxes that originally had held the coins and ingots was gone after 140 years. In many cases, however, stacks and rolls of gold coins retained their original shape, as though the walls of the wooden boxes still held them in place, the result of the organic glaze that cemented them together.
All of the gold was encrusted with some rust, calcium carbonate or other deposits, to a lesser or greater degree. Evans said that limestone tended to form in enclosed places, such as among the coins found in rolls. Overall, rust was more prevalent than limestone, Evans noted.

Photographs taken of the coins and ingots at the bottom of the ocean and after they were brought to the surface show an unlimited range of encrustation. On many coins, their golden surfaces still glittered under Nemo's lights, with even their dates visible; they were only lightly coated. The rust turned many of these ingots and coins beautiful colors not normally seen on gold coins. Other pieces shown in the photographs, however, were so incrusted with rust, wood fibers and limestone that it was difficult to determine what they were. Many of the ingots looked more like masonry bricks rather than cast gold bars. Photographs show incrusted coins were that were recognizable as coins, but unmarketable and likely unattractive to a majority of collectors.

The Columbus-America Discovery Group had spent millions to recover the gold, which was not in a saleable state. Something had to be done.

Finding a solution

Having found the Central America’s gold and brought it to the surface, Evans and the Columbus-America Discovery Group faced two major problems: gaining legal title to the treasure, and removing the encrusting materials from the gold without harming the surfaces underneath.

The legal battle, which took more than a decade and was appealed all the way up to the U.S. Supreme Court, already has been the subject of thousands of words within the pages of Coin World. It was fought out in courtrooms, with centuries of maritime law, briefs and depositions the weapons of choice.

The battle to restore the coins and ingots to their original appearance was fought in the laboratory, with science the weapon of choice. As does any good scientist, Evans researched the literature and experimented before determining what removed the encrusting materials without changing the gold itself.

Evans found that there is not a lot of literature on the subject of rust on gold. Much of his research is original, exploring new scientific territory. He first tested his process on the ship's coal, which like the gold, was encrusted with rust. Once he was certain that the process safely worked, he began using it on the gold.

To illustrate how he removed the rust and limestone, Evans brought with him to Long Beach two 1856-S Coronet double eagles (probably the next coins to be offered to collectors). He also brought with him the tools and special agent used in the curating process. While Evans was forthcoming in showing Coin World what he does to the coins, he wants to keep the exact process proprietary. Others may find the process useful; if so, it may be worth a lot of money.

To perform his demonstration, Evans took Coin World behind the scenes, literally. He unlocked a hidden door in the Central America display on the bourse floor, just to the side of the freestanding display holding an 80-pound bar of California gold, the largest of its kind ever found. As he shut the door behind him, he held it shut with a simple wooden wedge.

Like the façade of a Western movie set, the SS Central America display is strictly one-sided. While the public sees a replica of a 19th century steamship from the outside, inside one finds unfinished wood. Wooden boxes are fastened to the walls to support the platforms on which rested the gold coins and ingots that the public could view through the "portholes." A plastic jug of distilled water and cardboard box of plastic peanuts rested on the floor. A simple table rested in the center of the enclosed space (which is small and not for the claustrophobic, by the way).

To begin his demonstration for Coin WorldEvans brought out his vessel of choice in which to soak the coins — a No. 11 Rubbermaid container, the kind one finds at Kmart. It is the perfect size to hold 10 double eagles, Evans explains, the coins resting flat at the bottom of the container. He buys them by the case, which keeps his costs down to $1.80 or so each.
Evans placed the two coins he brought with him into the Rubbermaid container. One of the coins was already fairly clean; it had already been through two soakings. The other was more encrusted, so coated with iron rust that it was hard to see a lot of detail; it had been through one soaking.

Evans opened a bottle and poured a clear liquid over the coins. As he poured, he explained that he starts with distilled water, to ensure that it is free of chemicals that might affect the process he was about to demonstrate. The solution also contained two sodium salts, "One of which is baking soda and the other's not," Evans said cagily. He wants the "other" ingredient to remain a secret to protect his process. The baking soda buffers the process and keeps it from going too far.

Evans then opened another container, which like the Rubbermaid container is an everyday object one might not expect to find as a scientist's tool — a plastic 35-millimeter film canister. As he opened the container, a sulfuric smell, the odor of rotting eggs, invaded the tiny enclosed room. Evans apologized, noting that some find the smell overwhelming. He also declined to identify this ingredient, again to protect his proprietary process.

He dumped the white powder into the Rubbermaid container holding the coins and the solution. When the white powder hit the liquid, the solution rapidly began to foam, and the sulfuric smell intensified. One could only think of the television commercial for the bathroom cleanser that uses tiny "scrubbing bubbles" to clean soap scum from shower walls, although it is doubtful any company would market a product that smelled like the agent used to clean the coins. The foam quickly dissipated, as did most of the smell, and the solution became clear again. Now it was time to wait.

Nothing terribly exotic

While waiting, Evans explained more about the process. He said there is "nothing terribly exotic about the chemistry." The solution has a neutral pH of 7.2, Evans said. Dipping his fingers into the liquid, he rubbed them together and commented that it feels slippery (he usually wears latex gloves when using the solution). Normally, he said he snaps the Rubbermaid container's lid into place to limit the amount of oxygen that is exposed to the agent. However, he left the container open during the demonstration.

Evans explained that the process breaks down the rust physically, and in no way affects the surface of the coins. Technically, iron ions are being sequestered or "complexed," not dissolved. The iron ions become bonded to another part of the agent, taking them away from the surface of the gold. He reiterated that the agent caused no chemical reaction in the gold, and noted that after the surface incrustations have been removed, they have found 140-year-old fingerprints on some of the coins (another indication that the gold itself is unaffected by the process).

Evans explained that it is important to understand that the gold itself has not toned, that the colors seen on the coins and ingots are the result of physical incrustations, not changes to the gold itself. Seawater pitting has not been a problem, either. While Evans is not sure why that is the case, he said it is possible that the alkaline nature of the surrounding environs might inhibit the chemical processes that cause gold to pit when immersed in seawater. He said the chlorine in the seawater will only attack the gold when a low pH is present. The pH of the surrounding water at the wreck site was 7.2. Ironically, the coating of rust and limestone may also protect the coins somewhat, Evans noted.

The solution in which the coins soak remains active for 12 to 20 hours depending on the amount of oxygen that gets to it, Evans noted. He often lets a container of coins soak overnight while the agent does its magic work on the rust and calcium carbonate deposits.

After letting the coins sit for a while, he picked up a small brush with red handle and white bristles. Evans explained it is important to choose a brush whose bristles are softer than the gold. Otherwise, one can imagine the coin becoming hairlined while being brushed.

Using the brush, Evans gently brushed the cleaner coin. Small flakes of rust became dislodged and floated away from the surface. He picked one up on the end of the brush to illustrate that it truly is a physical incrustation and not some sort of toning on the gold.

While most of the rust that flakes off takes the form of small particles, he has encountered a few coins with a really thick coating of rust that, after soaking in the agent, lifted free intact.

Evans showed Coin World one such piece. It formed a perfect mold of the obverse of the coin it had encrusted. The portrait of Liberty and the stars were as clear as a darkened die. While the piece was not completely intact, even a portion of the date could be seen at the ragged bottom of the chunk of rust.

Evans turned it over and explained that fibers of wood embedded in the rust gave that particular piece added strength and allowed it to be lifted from the surface virtually intact.

He also showed something remarkable. The inner surface of the rust even duplicated the luster of the coin it had once obscured. As Evans tilted the piece of rust in the light, the cartwheel effect of a lustrous Mint State coin reflected from its surface.

Evans noted that prooflike coins clean faster. He found it took longer to separate the rust from circulated coins because the rust was able to bond tighter to their surfaces.

For the purposes of the demonstration, Evans let the coins soak for 24 hours. He and Coin World checked on them after they had soaked for six hours. At that point, he was able to dislodge more of the rust.

After the 24 hours had passed, the coin that had just been through its third soaking was virtually free of rust. He brushed at it a few more times, then picked it up and held it over a rectangular oven-proof baking dish. He got a small plastic bottle of distilled water and squirted water over the coin, using a bit of "kinetic action" to remove the last of the rust. The product was, in Evans' estimation, an About Uncirculated 58 specimen.

The second piece, which had just been through its second soaking, was much cleaner than it had been when it began, but it was not ready for sale yet. Evans said it needed at least one more treatment before it was ready.

Evans said that back in the laboratory, the coin that was done would be bathed a final time in distilled water, then in alcohol to prevent water spotting. Finally, it would be dried under a hair dryer at cool heat.

Evans might have 300 coins soaking in the lab at any given time, he said. At that time, he said he had a slightly smaller number being processed.

Some collectors have been critical of reports that PCGS has graded and encapsulated the SS 
Central America coins. That especially has been true for those collectors who have had coins returned in "body bags" as ungradeable because they had been cleaned. Some collectors writing to Coin World have questioned whether a double standard exists for small collectors and big dealers.

Evans hopes that by sharing much of the process, critics will have a better understanding of what is being done to the coins.  He believes that there is a difference between the harsh level of cleaning that will result in a coin being returned in a body bag, and what he does.

The discovery of the SS Central America and the recovery of its treasure worth millions of dollars is one of the major numismatic stories of the century almost past. However, the story of how these coins and bars are being freed from their coatings to again shine is one that should also be remembered by collectors in the years to come, not only for the controversy that surrounds the process but for the science behind it. It seems clear that without Evans' research and scientific skill, the 1857-S Coronet double eagles that were recently sold on the market might be so much rust-coated bullion and not the prize of someone's collection.