Tank treatment

Turco Product Division, Purex Corporation. When combined with vapor degreasing and alkaline cleaning, this process offers very high-strength bonds on titanium. Plasa Jell is also a proprietary chemical marketed by Semco Division, Products Research and Chemical Corp. This formulation is available either as a thixotropic paste suitable for brush application or as an immersion solution for tank treatment. 

On February 21, 1959, an exhibition with 20-30 sculptures from the Wasa was opened at the maritime museum in Stockholm. Those sculptures were brushed with PEG solution before, during, and after the exhibition. Later in 1959, the lion figurehead and a few smaller sculptures were preserved with PEG by tank treatment. 

Tank Treatment. Tank treatment followed the schedule recommended by Moren and Genterwall (5), which prescribed a 10% PEG concentration and a temperature of 30 °G as the starting point. The concentration was successively raised by adding a 10% PEG solution to replace evaporated water. The temperature was raised according to a preset schedule as the PEG concentration went higher until it reached 70 °G. The PEG concentration was brought to 100% thus most of the water was removed from the wood. 

After the laboratory tests, all the tank treatments were started by heating the material in water with only the boric acid-borax mixture, before adding any PEG at all. An individual schedule was adopted for each batch of material that was to be tank-treated. These schedules specified the end-point concentration of PEG and the daily increments during various parts of the preservation process, depending on the status of the material and the status of knowledge. 

The treatment of the Wasa material, both pine and oak, was performed at 60 °C. PEG 4000 was used for the tank treatment. The schedule for the pine had a higher end-point concentration of PEG in the solution and a faster pace of raising the PEG concentration than that used for the oak material. 

Difiusion processes are encouraged when a PEG solution in water is brought into contact with pure water or with a PEG solution of a different concentration. The obvious difiusion situation is tank treatment. The almost continuous spraying of the Wasa hull was an attempt to create a similar situation without a tank. 

The preservation solutions used for the spraying of the Wasa hull and the tank treatments of disconnected material have consisted of solutions in water of PEG, boric acid, and borax. The concentration of PEG of each solution has been brought from a low level at the beginning of the process... 

Painted waterlogged wooden objects present a problem because the paint layer or patches of paint are prone to come off during tank treatment with PEG. This has occurred with the very insignificant paint residues on the Wasa sculptures. If, on the other hand, the wood is not treated with a dimension-stabilizing agent, the paint layer normally comes off because of the shrinkage of the wood. 

Both liquid/gaseous ammonia and metaUic sodium are widely used in industry, but not for treatment of hazardous wastes. A Subtitle X permit is required under RCRA for processes that treat wastes regulated as hazardous in nonstandard ways. (Standard treatment processes, such as incineration and tank treatment, are permitted under other RCRA subtitles.)... 

The 163-N facility contains demineralization equipment, including ion exchange units, regeneration tanks, treatment tanks (for pH adjustment) that are part of the elementary neutralization unit (ENU), acid and caustic-materials storage tanks, a heater, and a degasifier (DOE-RL 1990). 

Pasa-Jell (www.bergdahl.com/PasaJell.htm) is a proprietary chemical marketed by Semco Division, Products Research and Chemical Corp., Glendale, CA. This formulation is available either as a thixotropic paste suitable for brush application or as an immersion solution for tank treatment. Pasa-Jell 107 is a blend of mineral acids, activators, and inhibitors, thickened using inorganic agents, to permit application in localized areas. The approximate chemical constituents are 40% nitric acid, 10% combined fluorides, 10% chromic acid, and 1% couplers, and the balance is water. The immersion process requires nonmetallic tanks made of polyvinyl chloride (PVC), polyethylene, or polypropylene. A recommended mixture uses 1 1 dilution for 12 min. With the thixotropic Pasa-Jell paste, a reaction time of 10—15 min assures durable bonds. ... 

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