Paint appearance is one of the most important property required by automotive industry. It is affected both by painting process and surface substrate. The aim of this paper is to link the steel substrate and painting appearance with regards of painting process.
Helped by Wavelet transform technique we point out the levelling power of each paint layer. Thus it appears that only substrate waviness affects paint appearance.
A waviness criterion is developed in this paper. It permits to highlight the influence of cure position and spray movement. This criterion is also able to help steelmakers to control the temper rolling steps as it is show in a last part.