Preservation Methods

Stopgap Measures and Permanent Solutions 

After the Neuse was taken to its present location at Caswell Memorial Park in the spring of 1964, it was mounted on oaken supports and pressure washed to remove sand and mud. The ship was then treated with a five percent solution of pentachlorophenol and polyethylene-glycol. Two applications of this solution, consisting of 1,500 gallons, were sprayed on the vessel. This treatment prevented the attack of wood-eating insects, but did not penetrate the wood well enough to combat the ravages of constant exposure to weather. Deterioration continued, with large chunks of wood flaking off and crumbling.

The roof over the ironclad's remains provided only partial protection against the elements. Blowing rain and snow, along with fluctuations in temperature, continued to speed the rate of decay. It became apparent that the vessel would need further treatment.

Blocks of wood were selected from various parts of the ship for analysis and treatment. These test blocks revealed that some "heart" areas contained a large quantity of moisture. The surface areas of the blocks, however, appeared relatively dry, with textures ranging from a powdery state to loose flakes.

When the vessel lay submerged in sand and water prior to the salvage operation, natural saps and resin were leached from these surface areas. After removal from the water, these areas dried rapidly and began shrinking and separating from the more solid cores. As rain fell on the ship, surface areas became saturated with water, which dissolved more sap and caused swelling. During dry periods, moisture and sap evaporated, causing the surface to shrink. This constant drying and swelling of wood fibers already damaged from submersion increased deterioration daily.

Selecting a Method of Preservation

Several preservation methods were considered to help slow the decay of the Neuse. Painting or impregnating the wood surface with a plastic resin was considered—a process used on another gunboat similar to the Neuse. This approach was abandoned, because large amounts of moisture in the water-logged areas near the stern would have become trapped with the seal of resin. Other factors against this method included the inability to completely seal the cracks between timbers which resulted from improper drying.

The hull remnant needed an impregnating solution with the following qualities:

1. Resistance to weathering (evaporation, moisture, temperature, etc.)
2. Protection against efflorescence and disintegration.
3. Resistance to insects and fungus.
4. Penetration depth sufficient to reach all affected areas.
5. Versatility for allowing the addition of future treatments.
6. Prevention of the hull from assuming an altered or distorted appearance.

Using test samples from the hull, experiments were conducted at the Fort Fisher underwater archaeology facility in Kure Beach, North Carolina. Impregnating solutions tested included polyethylene-glycol, hydrozol, ceresin wax, and linseed oil. The tests were carried out under conditions in which the ship itself might be treated. After evaluating the results, state conservationists chose linseed oil as the best solution for treatment. This agent, when diluted, offered a greater depth of penetration and retainment than other materials tested. The linseed oil proved moisture resistant, combined well with insecticides, and could be applied without the use of expensive equipment.

The remaining hulk of the ship contained approximately 5,000 metal spikes and pins, with varying degrees of oxidation. The majority of these were found to contain heavy surface rust with some pitting. Several of the spikes were removed and treated with various rust removers and inhibitors. A solution known as Manganese-Phospholene #7 proved to be the most useful in removing rust from the exposed parts of spikes and pins which could not be removed from the wood. This material requires no washing or neutralization. It does not harm wood and acts as a paint primer after drying. An inorganic zinc silicate coating, known as Dimetcote #4, was selected as a final protective coating for the iron spikes and pins. Past use of this coating has yielded excellent results on other metallic artifacts in similar condition.

Determining Quantities of Materials Needed

Test results indicated that the entire surface area of the Neuse's remains would retain an average of approximately one quart of linseed oil per 10 square feet when applied as follows:

• First application - 50 percent linseed oil with mineral spirits.
• Second application - 50 percent linseed oil with mineral spirits.
• Third application - 100 percent linseed oil.

The surface area of the Neuse's remains was calculated to be approximately 15,000 square feet. At the rate of one quart of linseed oil per 10 square feet, 400 gallons was a sufficient quantity for the application process. One-half or 200 gallons of linseed oil was diluted with 200 gallons of mineral spirits to form a 50 percent solution for the first applications. Concentrated pentachlorophenol (insecticide) was added to the first two applications of linseed oil and mineral spirits. Forty gallons of 50 percent pentachlorophenol formed a 5 percent solution, which is recommended by the manufacturer. As a final precautionary step to prevent runs and surface beading, a light spray mist of diluted wood sealer was applied.

An estimated 4 gallons of Manganese-Phospholene #7 (rust remover) and six gallons of Dimetcote #4 (coating) were needed for all exposed spikes and pins on the vessel. Other materials such as paint brushes, drill brushes, and containers were purchased locally in reasonable quantities.

Application of Preservation Treatment

Linseed oil treatment of the Neuse was begun on February 10, 1971. Efforts to clean to gunboat with small vacuum cleaners and air compressors were unsuccessful. A large commercial air compressor was then employed. A two-foot section of pipe, one-half inch in diameter, was connected to the compressor hose. This attachment allowed penetration into the vessel's cracks and crevices where most of the sand and foreign materials were found. The debris was systematically blown from the sides of the ship, and the bottom of the vessel was swept clean. It took three workers a total of nine days to clean approximately five cubic yards of sand, leaves, and decayed wood from the remains of the Neuse. During this process, several small artifacts were found on the ship, including a marble, two brass buttons, and two bullets.

A decision was made to treat only the exposed areas of the spikes and pins, as their removal would jeopardize the soundness of the ship's structure. The work crew adopted the most practical method of treating the exposed portions of the metal fittings:

1. Each was given a sharp blow with a flat-faced hammer to loosen flakes and particles of dust.
2. Electric drills, with course cup brush attachments, were used to remove scale and rust particles.
3. Manganese-Phospholene #7 was brushed onto all exposed metal to complete the rust removal. Dissolved rust was wiped away with a clean cloth after application. Two hours were allowed for the rust removal solution to dry before the protective coating was applied.
4. The prepared metal parts were then coated with Dimetcote #4. Care was taken to prevent runs or dripping. Four weeks were allowed for the coating to cure. Four days would have been sufficient, but inclement weather and conflicting work schedules interrupted original plans.

A centrifugal pump, driven by the power-take-off of a small farm tractor, was selected for applying the linseed oil. This pump, commonly used on farms for applying insecticides and plant nutrients, proved to be quite effective in spraying the viscous impregnating solution. An ordinary garden hose and spray nozzle were sufficient to obtain the proper coverage of the spray.

The moisture for the first application consisted of 100 gallons of mineral spirits, and 20 gallons of pentachlorophenol. The solution was sprayed on the gunboat at a rate of approximately one gallon per 70 feet of surface area. Areas which appeared to be overly dry received a larger quantity than areas in a better state of preservation. One week was allowed for evaporation of the excess mineral spirits.

The second application was mixed and applied as the first, a process which consumed two working days. The third application, consisting of 200 gallons of linseed oil, was begun after a waiting period of two weeks. The third application was accomplished in one working day.

After allowing nine weeks for maximum penetration of the impregnating solution, and evaporation of the mineral spirits, the ship was sprayed with 30 gallons of wood sealer diluted with a 25 percent solution of mineral spirits. This final stage consumed two working days.

Remarks

Several factors must be considered in seeking the most effective means of preserving any valuable artifact. These include the condition of the artifact, its composition, where it was recovered, size, shape, and where the artifact is to be displayed. Before preservationists can apply permanent treatment, they must know what the results of the treatment process will be. This is absolutely imperative when dealing with a one-of-a-kind artifact such as the Neuse.

In many cases, where fool-proof methods of preservation cannot be found or financially afforded, temporary measures may be taken to stabilize the condition of the artifact until a permanent solution can be reached. This proved necessary in preserving the remnants of the Neuse. Linseed oil impregnation was intended as a conditioner against weathering. It was applied to replace saps and resin which had been previously lost by water and climatic conditions. This material softened the wood fibers and made them more pliable, thereby reducing crumbling and breakage in the presence of dry air or moisture.

In late 1996 site staff, at the recommendation of state preservationists, began using Tim-bor (sodium borate) as a preservation treatment for the remains. This treatment has replaced the use of linseed oil and mineral spirits. Tim-bor is an insecticide, fungicide and wood preservative for the protection and treatment of lumber against fungal decay and wood destroying insects. Tim-bor is a water soluble, inorganic borate salt with insecticidal and fungicidal properties. It is an effective treatment for wood to kill and prevent infestations of decay fungi including white rot, brown rot (i.e. Poria) and wet rots. The treatment has been sprayed onto the remains as needed to slow deterioration until the Neuse could be moved into a more stable, climate-controlled environment.

In 2012, the remnants of the CSS Neuse were moved to a new, fully enclosed and climate-controlled facility in downtown Kinston. Temperature and humidity within the space are controlled, and conditions are monitored as the remains continue to acclimate to the new environment.

Artifact Preservation

Artifacts from the Neuse were delivered to the state's Underwater Archaeology Unit at Fort Fisher for treatment in 1965. Considering their 100-year residence underwater, they were in a remarkably good state of preservation. The lack of water salinity and the ship's having been covered in sand and mud for much of this time accounted for their good condition.

In 1965, the science of preserving artifacts from underwater environments was in its infancy. Typically, lack of funds and the urgency of the Neuse's supporters to display the items dictated, in many cases, the method of preservation.

Artifacts from the Neuse were generally divided into three categories: metallic, organic, and compound. In most cases sturdy metallic artifacts were sandblasted to remove scale and rust. They were then dried in an oven at 212 degrees for 48 hours, after which they were coated with polyurethane, or epoxy resin. After the initial coating dried, iron filings were mixed in a second coating to eliminate gloss. Fragile metallic artifacts were cleaned by electrolytic reduction. The objects were suspended in an electrolyte solution of five percent sodium hydroxide. The negative pole of an electrical current rectifier was attached to the artifact, and the positive pole to metallic plates also suspended in the electrolyte. When the current (approximately 10 amperes per square foot) was passed, hydrogen gas evolved, softening and removing the corrosion layer on the surface. Drying and coating were carried out as described above.

Organic artifacts were cleaned by manual washing or brushing, or with diluted phosphoric acid when foreign matter persisted. They were then soaked for one to two weeks in polyethylene-glycol of various molecular weights, ranging from 400 to 4,000. The higher weights were diluted 25 to 50 percent with water in order to keep them in solution. The organic materials were then air-dried for two to four weeks before an insecticide was applied. After drying two to four additional weeks, a clear diluted wood sealer was applied. Additional coatings were applied until no more could be retained. In some instances a flat vinyl coating was applied to prevent the appearance of glossy surfaces.

Compound artifacts—those composed of both metallic and organic materials—were disassembled before or during cleaning. Diluted phosphoric acid was employed to aid this process. The separated materials were then treated in the manner described above. Ceramic and glass items were manually cleaned only. The absence of stains prevented the need for further treatment.

Photographs and scale drawings of objects pulled from the Neuse were made at the lab, and other pertinent data was recorded throughout the treatment process.

Adapted From:

CSS Neuse: A Question of Iron and Time, by Leslie S. Bright, William H. Rowland, and James C. Bardon (North Carolina Office of Archives and History, 1981).