A new colorant which fades from purple to clear may solve the problem of uneven coatings on the outsides of tanks.
The fugitive colorant, Series 44-500 Skip-Saf™ from Tnemec, is designed to help facilitate uniform application of clear protective finishes to water storage tanks and vessels.
Added in the field to Tnemecs clear urethane topcoats, Skip-Saf is a translucent-colored tint that "dyes" the urethane topcoat purple, allowing the applicator to clearly see the work in progress. This helps prevent skipping of areas, aids in the application of correct film thickness and makes apparent any runs or sags.
Within four to 72 hours? exposure to direct and indirect sunlight, the purple tint disappears, allowing the substrate to retain its original colors while leaving a clear topcoat that protects the coats beneath from ravages of the weather.
?A uniform application of topcoat provides better overall protection to underlying pigmented coatings from weathering and fading,? Bauer said. ?If clear coats are applied unevenly, the skipped areas will begin to fade over time, resulting in an unsightly water tank and an unhappy owner.?
According to Walt Neumann, president of Neumann Company Contractors, Inc., Romeoville, Ill., the colorant has made it easier for his employees to apply clear coatings to water tanks.
?When using a clear coating, the applicator is prone to miss spots that won?t appear for three or four years,? said Neumann. ?On bright, sunny days it?s extremely difficult to see where the coating is being applied due to glare.?
The Series 44-500 Skip-Saf is patent-pending and currently available for use with Series 76 Endura-Clear, a clear polyurethane coating from Tnemec. The colorant is packaged in a pre-measured vial and sealed in a Mylar packet that is included with Endura-Clear.
Addition of the colorant to shipments of the coating has added three percent to the total cost of the clear coat, Bauer said. But, he added, ?A slight three percent increase to product cost will have minimal effect on the total job cost and is more than outweighed by the money it will save on costly repairs in the future.?
Tnemec coatings are certified under ANSI/NSF Standard 61 for coatings to be used in direct contact with drinking water. The coatings can be used for interior and exterior of tanks.
About the coating:
Endura-Clear, the polyurethane clear coat that includes the fugitive dye, is used as a final coat which enhances the finish and extends the long-term weathering qualities of pigmented Endura-Shield, another coating from the same company. The high gloss clear coat resists most graffiti. It is designed to be sprayed on, but can also be rolled on. The clear coat can be applied over base coats from 7 to 21 days after the base coat is applied. The clear coat is dry to the touch after 1/2 to 1 hour, dry enough to handle after 2-3 hours, and dry enough to recoat after 3 hours. It is dry enough to resist moisture condensation after 3 hours.
