Royston A-51 & A-51 Low VOC
Thixotropic brush applied coal tar coating
Royston Roskote A-51 is a time proven coating technology for providing corrosion protection to metal fittings, flanges, valves, tanks, mechanical couplings, anode connections and other difficult and irregular configurations. It is also designed to protect concrete surfaces from adverse environments and is easy to apply by brush or rubber glove. Due to the thixotropic nature, it resists drips and sags during application but will become more flowable the more it is brushed.
The A-51 Low VOC has a VOC content of <327 g/l (2.73 lb/gal) and shares all other properties with the regular A-51 and TC Mastic.
• High electrical resistivity designed to protect underground steel pipes, tanks and other structures against corrosion particularly in soils saturated with oil and gasoline.
• Excellent above ground coating for protection against severely corrosive atmospheric fumes and against moisture and salt in coastal areas.
• Bonds firmly to steel surfaces without the use of primer.
• Forms a tough coating which becomes resistant to oxidizing, crazing, alligatoring, cracking, checking, loosening or scaling.
• Endures over a long period of time because of its resistance to soil stress and to attack by alkalis, acids, salts, moisture, gasoline and oil.
Surfaces should be dry and cleaned of all rust, scale, soil, mud, oil, grease and other contaminants in the field by wire brushing. Sand blasting or chemical treatment may be more convenient for in-plant surface preparation. No primer is required.
Royston Roskote A-51 should be stirred thoroughly before using. Thinning is not required except for cold spray at temperatures below 60oF. The heavy mastic is specially formulated to obtain a thick protective coating. If excess thickening occurs because of solvent losses from opened containers, restore to original viscosity with Royston Thinner No. 70 or a mixture of equal parts of toluene and MEK.
Apply cold by brush, glove or booster-pump spray. Apply to cover 65 to 70 square feet per gallon, which will provide a dry film thickness of about 12 mils per coat. When the first coat has dried to the touch, which will usually require less than an hour, apply a second coat at the same thickness.
Brush and Glove Application
Apply liberally with a generous amount at all times. It should never be applied thin. However, a wet film thickness of .040 inches is maximum per coat to reduce the possibility of mud cracking.
Booster type spray equipment is required because of Royston Roskote A-51's heavy consistency. It may be sprayed with minimal thinning at temperatures above 60 F. It is usually necessary to thin with one quart of thinner to each five gallons of Royston Roskote A-51 in temperatures below 60oF. Use high boiling (250oF) mineral spirits for spray thinning.
Either air type or airless spray equipment commercially available from several manufacturers may be used. The following equipment procedures have provided satisfactory results, but alternates may be equally successful.
Good spray results can be obtained with an airless high volume 10:1 pump with air cap assisted atomization, e.g., Binks Model 98-792 outfit or equal.