Support from technical specialist helps refinishers avoid pinholes and other small surface defects
Spies Hecker, one of the premium refinish paint brands of Axalta, a leading global supplier of liquid and powder coatings, knows that even a seasoned refinisher can sometimes run into issues with tiny defects such as pinholes appearing in the clear coat.
Tony Mitchell, International Training Leader, for Axalta’s Refinish business in Europe, Middle East and Africa, says, “These types of defects are not only annoying but also costly, especially in busy bodyshops. Our tried and tested advice can help refinishers avoid them happening in the first place.”
1. The right surfacer shade
The most frequent cause of defects, such as pinholes, in the clear coat is overloading the base coat during application. This can easily be avoided by ensuring the right surfacer colour is used as this will mean less base coat is needed. Refinishers can find the recommended surfacer colour for every base coat colour in the Phoenix colour software.
2. Adjust the base coat correctly
Another common mistake is that users do not adjust the base coat correctly to match the climatic conditions in place at the time of application. Mitchell says, “Always check the Permahyd Hi-TEC 480 Base Coat Technical Data Sheet (TDS) and climate guide to find the information on adjusting the base coat for the conditions in your bodyshop.” This will help make application easier and prevent overloading of the basecoat.
3. Reduce process errors
Spies Hecker Permahyd Hi-TEC Performance Component WT 455 has been specifically developed for use in solid colours to help reduce process errors. Mitchell says, “It improves the handling of the basecoat, offers a smoother surface and will enable easier application and improved appearance of the clear coat. We recommend using this in hot conditions where the Relative Humidity is below 50 percent.”
4. Don’t forget the spray gun
“When trying to avoid defects, everything matters, even the spray gun set-up, so choose an appropriately sized nozzle and the recommended inlet pressure. Please follow the guidelines in our Spies Hecker TDS for the best results,” says Mitchell. A larger nozzle means more product is being applied and that increases the risks of defects including pinholes, mottling and of course problems with colour. If the pressure is too low, the film thickness will be higher, again leading to problems. “But don’t get caught in the trap of having too high an inlet pressure as that will mean more air being trapped in the wet surface, which may lead to pinholes,” Mitchell adds.
5. Flash off
Refinishers can use a hand-held Venturi when drying the base coat, but not when the base coat is activated. Care, however, should be taken with the inlet pressure – Spies Hecker recommends a maximum of two bar – and with the distance from the surface – the recommendation here is a minimum of one metre.