Starch media blast cleaning of artificially aged paint films

Starch media blast cleaning is an environmentally benign coating removal pr ocess increasingly used as an alternative to traditional coating removal te chniques. The main objective of this work was to provide a method for predi cting the paint stripping rate of an aged paint system, through a knowledge of some fundamental physical properties of the paint/substrate system (e.g . hardness and modulus of elasticity). It was shown that aging of the alumi num panels painted with polyurethane significantly increased the hardness o f the coatings, but did not have a significant effect on the coating modulu s of elasticity. It was also shown that the coating became more erosion res istant as it aged, and that it was possible to predict the paint removal ra te by in situ measurement of the coating dynamic hardness and coefficient o f restitution. It was concluded that coating erosion resistance increased w ith increasing coefficient of restitution. The relative erosion resistance of the aged coatings was explained on the basis of differences in modulus o f elasticity and dynamic hardness. As expected, for a constant modulus of e lasticity, a higher dynamic hardness gives higher erosion resistance. (C) 2 001 Elsevier Science B.V. All rights reserved.