The Los Alamos National Laboratory tested twenty leading solvent substitutes.
Why aren't any these products distributed by ICI-and why isn't Delta
using any of them.I'm sure these companies do thier DD.
Napier is patented.
It found X-Caliberr to be the most efficient and versatile, an excellent paint stripper, as well as a good substitute for methylene chloride and acetone. The only limitation noted was that X-Caliberr has a slower evaporation rate then acetone, requiring an extended drying time. At $5.70/pound, X-Caliberr costs more than methylene chloride ($0.43/lb). However, because X-Caliberr is ten times less volatile than methylene chloride, it's use cost is only $0.57/pound. In addition, X-Caliberr has a contaminant-loading capacity 4-6 times greater than methylene chloride.
Citrexr is another of Inland's terpene-based strippers. This cleaning and stripping agent can remove a variety of contaminants, including paints, coatings, carbon, grease, fuel residues, and resins. Its stripping performances equal those of traditional cold-tank compounds, such as methylene chloride and dichlorobenzene, but Citrexr has none of the toxicity and disposal problems associated with them. Citrexr contains no chlorinated solvents. Its components are not listed on the EPA's TRI, nor are they SARA reportable. Citrexr can be safely used on both ferrous and non-ferrous metals, as well as sensitive metals such as aluminum, magnesium, and titanium. It sells for $5.70/pound; however, like X-Caliberr, its high level of cleaning efficiency makes its price comparable to other stripping agents.
Gaylord Chemical (Slidell, LA), is the world's leading producer of dimethylsuloxide (DMSO), which is derived from natural raw wood lignin, or black liquor, a byproduct of paper milling. Gaylord manufacturers DMSO from lignin produced by Gaylord Container's pulp and paper mill in Bogaluse, LA. DMSO is a powerful organic solvent that is used for stripping paints, coatings, and adhesives. It can replace listed petrochemical solvents such as methylene chloride, n-methyl pyrrolidone (NMP), and dimethylformamide (DMF). DMSO is not listed on the TRI, nor as a hazardous air pollutant (HAP). It costs $0.96/pound, comparable to solvents of similar strength, such as NMP and DMF ($0.83-$1.85/lb). DMSO also has a low toxicity, creating a safer work environment.
Blasting Technologies Using Natural Materials
CAE Electronics (Alpharetta, GA) patented an abrasive stripping process, EnviroStripr, using wheat starch as the blasting media. Using low-pressure air, the process propels particles of crystallized wheat starch at a painted surface. The coating is stripped away by a combination of impact and abrasion. Wheat starch blasting can remove a variety of coatings, paints, adhesives, sealants, and composites. Its gentle stripping action can remove individual coating layers, such as removing a topcoat while leaving the primer intact.
Wheat starch-blasting has several advantages over chemical stripping. It uses non-toxic, biodegradable media derived from a renewable agricultural product, rather than petroleum, reducing the consumption of non-renewable resources. A completely dry stripping process, wheat starch-blasting generates no wastewater. Furthermore, the wheat starch can be collected and reused for numerous blasting cycles. When the media is finally spent, it can be disposed of via landfilling, incineration, or biological treatment. If a biological treatment process is used, the waste requiring subsequent disposal is estimated to be only 5% of the original volume. The cost of biological treatment is estimated at $0.75/pound for 50,000 pounds, and $0.50/pound for 150,000 pounds or more. Biological treatment is the most economical when the spent media volume is greater than 50,000 pounds.
Capital costs for a wheat starch-blasting system vary, depending upon applications, but a plastic media-blasting system can be modified to utilize wheat starch for approximately $10,000. Wheat starch media costs between $1.60-1.70/pound, and can be reused in the system for 15-20 cycles. The operating costs for wheat starch-blasting systems have been estimated to be 50% less than chemical paint stripping (e.g. methylene chloride). Wheat starch-blasting also produces 85% less waste sludge as chemical stripping, substantially reducing disposal costs.
Walnut hull-blasting is another paint removal process that uses a naturally-derived abrasive media. This process is used primarily for specialty paint-removal applications, such as automotive restoration. To strip paint from its rare Porsches, Aase Bros, Inc. of Anaheim, CA, prefers to use walnut hull blasting rather than chemical stripping because it does not distort the metal. Although the process is slower and rather dusty, it produces significantly less waste than does chemical stripping. Typically, less than 10% of the dust generated by walnut hull blasting requires a special disposal method (i.e., landfill), thereby reducing disposal costs. Walnut hulls cost between $0.47/pound (50lb bag) and $0.007/pound (2,000lb bag). The blasting system costs $1,000-25,000, depending on the size of the unit and type of application. For example, a 53 ft3 blasting unit costs approximately $25,000.
Carbon dioxide (CO2) blasting, another alternative stripping process, converts liquid CO2 to dry ice flakes (or pellets), which are then projected by compressed air onto a targeted surface. As the dry ice pellets strike the surface, they induce a thermal shock between the coating and the underlying substrate, weakening the bonds between the two layers. Immediately after impact, the pellets vaporize, releasing CO2 gas along the surface and dislodging the coating (or contaminant) from the substrate. CO2 blasting effectively removes paints, sealants, carbon, grease, oil, flux, and adhesives. Waste disposal is minimal, because the CO2 pellets disintegrate. Thus, only the coating or contaminant residue remains after blasting. Also, the CO2 stripping is 80-90% faster than chemical stripping.
CO2 pellet blasting systems can be purchased for $25,000-$50,000, or rented for $1,500-$2,500/month. The pellets cost $0.10/pound to $0.50/pound (price based on delivery distance). For $50,000-$130,000, a manufacturer can purchase a pelletizer and make pellets on-site, reducing the cost of the pellets to $0.10-0.15/pound.
References
1. Product information provided by Eric Lethe of Inland Technologies.
2. Product information provided by Rod Willer of Gaylord Chemical.
3. U.S. Dept. of Defense, "Wheat Starch Blasting", Pollution Prevention Technical Library, June 1995.
4. Information provided by Phil Hicks of MC Abrasive Cleaning Equipment.
5. NFESC, Pollution Prevention Technical Library, "CO2 Blasting Operations
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