PAINT

Problem Solving

Paint

• Touchstone conducted a microscopic examination of paint and plaster samples. The analysis identified the unknown fibers in the specimen as human hair. The practice of using hair collected from barbers was historically a common way to increase plaster strength in “plaster and lathe” construction before rocklathe or standard drywall sheet were invented.
• Touchstone performed evaluations of a paint system for roof deck application for a roofing sheet manufacturer. The tests included 100 hour ASTM B117 salt spray testing.
• A metallographic study was performed for a coil coating company concerning the variability and total paint film thickness.
• An analysis was performed on paint chip samples taken from a bridge. The chips were analyzed in accordance with the ASTM methods for the determination of metal content of organic materials to determine whether lead or other metals were present.
• The purpose of this investigation was to determine the source of the black streaks on the surface of sheet steel and to determine if these black streaks were contributing to the blisters found on the as-painted steel surface. It is believed that these silicon-based particles were rolled into the surface of the steel sheets. The fact that they are elongated into ‘streaks’ rather than existing as ‘spots’ supports this thinking. Also, more importantly, they are not found at any location across the thickness of the sheet nor are they found on the opposite steel surface. It was shown that the black streaks did contribute to the paint blistering.
• A manufacturer of roll formed painted roofing materials was experiencing crazing and poor adhesion during roll forming. Touchstone performed an investigation and determined that pre-heating of coils increased the formability of the coatings which eliminated the crazing and adhesion problems. The procedure was incorporated into the manufacturing process and the crazing problem was eliminated.
• A water treatment plant, which services a coil coating line, experienced substantially more sludge than normal. Touchstone was asked to investigate. Samples were taken back to the laboratory from various locations in the plant as well as from the wastewater treatment facility. It was determined that a change in product mix from processing cold rolled steel and galvanized sheet to cold-rolled steel only increased the volume of sludge generated by the water treatment plant.
• A manufacturer of oil filters encountered a paint adhesion problem with their oil filters. It was thought that the tin-plate sheet from which they are formed was contaminated. Problem steel samples and samples of “good” tin-plate were supplied to Touchstone for comparison. Both suppliers of tin-plate were found to be in a clean state as-delivered. The company continued its investigation of the problem inside its plant.
• A steel company which supplies steel to an after market automotive parts supplier contacted Touchstone with a problem. When the automotive parts company had painted the steel with their normal process, major paint defects developed and samples of the product were returned. Touchstone evaluated the problem via scanning electron microscopy and metallography and found that alkaline cleaner salts had not been properly removed in the steel plant. This led to a poor phosphate pre-treatment. After forming and painting, the paint would not adhere well to this poor phosphate coating.
• A manufacturer of galvanized electrical conduit contracted with Touchstone to perform a study to compare powder paint coatings of the otherwise unprotected threaded area to metallizing for corrosion resistance. Salt fog tests were performed and it was found that the powder paint coating protected the steel threads as well as metallizing in salt fog exposure.
• A coil-coater developing a new coated, roll-formed steel product requested that Touchstone determine whether the higher than normal operating temperature of the curing oven had any affect on the brittle, zinc/iron layer always present in galvanized steel. The results of a laboratory-scale study of the process performed at Touchstone found that there was no increase in the size of the zinc/iron layer due to the change in thermal processing.
• A truck manufacturing plant was experiencing peeling of the paint on the exterior of roof panels. An investigation at Touchstone found that the zinc substrate lacked an effective pre-treatment coating.
• Touchstone regularly performs numerous failures of prepainted steel and aluminum building products such as roofing, siding, gutters and many others. Problems with dross, scale, “orange peel,” hardness, improper cure, off-color appearance, and adhesion are often discovered. Touchstone has a complete paint evaluation laboratory including: pencil hardness, microhardness, various abrasion tests, solvent wipe tests, scanning electron microscopes with X-ray microanalysis, etc.
• Touchstone evaluated 5 different water-based coatings for a square tubing manufacturer to determine their resistance to condensation-type rust. Samples of each were placed in a Cleveland-condensing cabinet and periodically examined for the presence of rust. The results of this study helped the manufacturer to choose the best coating for their products.
• The paint system used for the solid fuel boosters of the Space Shuttle was evaluated to determine resistance to corrosion after experiencing launch conditions. Panels were prepared according to NASA procedures, heated and quenched in salt water to simulate launch use conditions, and tested according to ATM B117 Salt fog exposure resistance.

The above examples are only a sample of our work in this area. We would be pleased to provide any additional information you may require. We also invite you to review examples on our website of work that we have performed in support of other business sectors.