Among the many encrusted objects and artifacts found during the 1999 dive season, one of the more interesting was an ordinary cargo hook, tag number 42982, from the Cannon Wreck Site of the 1715 Fleet. When it was delivered to the laboratory by Captain Greg Bounds of the salvage vessel Bookmaker it was an unremarkable E.O., somewhat recognizable as possibly a cargo hook, it along with many other E.O.’s, was relegated to it’s proper container. When the time came to break it out of the encrustation, the hook itself was found to be badly deteriorated and so was the thimble that is typically linked into the eye of the hook. This was the bad news, so often associated with the recovery of iron artifacts. Little of the original pieces are intact, and the remainder is so soft or fragile we are fortunate to have even a shell encrustation of the object left over for casting purposes. There would be no casting made of this hook.

During the removal of the rock surrounding the iron hook and thimble it was noticed that the thimble still had fragments of the canvas chafing material around the outer rim. This canvas was used as a protective measure to prevent the rope, which encompassed the thimble from becoming worn or frayed. As the crust removal progressed and more of the canvas was exposed, the decision was made to recover and preserve as much canvas as possible. This would mean most or all of the thimble may need to be sacrificed in order to keep the fabric. The decision was much easier to make than the preservation was to accomplish. The thimble was still linked to the hook and the canvas was thick with rock through and through. To make matters more interesting, the whole conglomerate of rock and canvas was firmly and completely attached to the thimble.

The first step following the removal of rock manually with the air scribe was soaking the piece in Aracon. This is an acid so mild that it removes the minerals only, while doing no harm whatsoever to the base metal or fabric. The acid was replenished a few times and when no more rock was left to be dissolved, the piece was placed in distilled water to soak and to remove the acid. Several fresh baths of water later, the object was put into a bath of approximately 30% hydrochloric acid to remove the remaining iron and rust on the fabric. This last treatment with HCL, was effective in removing the bulk of the remaining rust and crud. The canvas was slowly and carefully peeled away from what remained of the thimble.

The canvas was intact, untorn and still in the circular shape of the thimble. A few lumps and bits of iron and rock were removed with dental tools and the canvas was again soaked in several baths of distilled water. Because the fabric was badly stained by the rusty thimble and the tar used to coat the rope when it was new, the canvas needed to be bleached in a weak solution of hydrogen peroxide. This treatment brought the canvas back to a color much closer to the original light brown. Once again, back it went into the water baths until the peroxide was removed.

So now we have the canvas with all of the impurities removed, the stains taken out and still in the original shape of the thimble. An examination of the piece shows that this is not a single thickness of fabric but a piece folded in half, forming a double thickness along the length. This looked like a good place in the conservation process to examine the construction of the fabric. The weft and the warp are at right angles and the thread count is 30 threads per inch. The fabric is tightly woven with thread that is not fuzzy like wool would be, but with an almost waxed appearance. It was a quality, machine made cloth.

The rest of the conservation effort at this stage is fairly basic. The ring of canvas was placed in a small container of heated polyethylene glycol. This treatment would be the same basic treatment used on wooden artifacts, but the PEG treatment of a piece of fabric this size is done in a matter days, rather than months required for wooden artifacts. The sides of the cup-shaped container were round, and the same diameter as the thimble, so the canvas was kept in the same original shape while in the PEG. After a few days of this final treatment the canvas was removed from the solution and placed over a form made of a few loops of stainless steel wire, matching the dimensions of the thimble. Simple air drying only took a day or two and the whole process was completed. The canvas retains it’s shape nicely, and is stiff enough to be handled due to the PEG penetration of the fabric.

This entire process took about a month and was worth the effort. It serves as a reminder that perhaps the only thing slower than the correct and proper conservation of shipwreck artifacts is continental drift.

Because our little ring of canvas began life as sailcloth, it should be noted that sails and rigging constituted a major expense in shipbuilding. More in fact, than the cost of the wood, although the sails were the lesser part of the cost. The canvas was priced by the yard and was supplied in narrow strips to be sewn together. This process of sewing strips of cloth together to make sails continued as long as sailing ships were made, well into the 20th century. As a rule the lower sails would require a heavier canvas than the topgallants and mizzen but cloth supplies and other factors were the determining element in the weight of sailcloth used. The cost of sailcloth varied considerably especially since it was subject to wartime disruptions in supply.

Much of the sail canvas was imported from Holland and France, and Spain was, at various times, at war with both of these countries. Supplies remained available, even though at a higher price during wartime. The cost of sailcloth was 81% of the total cost of sails. In 1668 the price for canvas of all types ranged in price from 1.25 to 2.25 reales per yard. Using the formula provided in Six Galleons for the King of Spain. The Johns Hopkins University Press, U.S.A. 1986 pg82, we can estimate a 500 ton ship requiring 4 yards of canvas per ton, and canvas costing 2 reales per yard, would cost approximately 4,000 to 5,000 ducados to equip with a full set of sails. Ships normally carried two full sets of sails.

Recycling of equipment saved money and made the most efficient use of the available materials. Cables, anchors, certainly artillery, ropes, lines and any other gear that could be reused, was. The man in charge of the crown equipment in Cadiz registered even tattered sailcloth in the warehouse accounts as he took it in, just as he registered the other sails he distributed. Some sails would be used to cover storage boxes for biscuit, powder, and other sails, to protect from rats. We know also, that sailcloth was used on cargo hook thimbles to prevent the rope from chafing. Sails made up such a large portion of the cost of a ship, that whenever possible, the sails along with other rigging and materials were salvaged from sunken vessels. Everything of value was salvaged, and inventoried, to be distributed to the other ships in the fleet (Six Galleons for the King of Spain, pg.199).