Who is correct in using different spray guns for the topcoat and undercoat?

Using different spray guns for the topcoat and undercoat is important for achieving the best finish and ensuring proper application of each type of product. Different materials often require specific spray gun designs and operating parameters to perform optimally. For instance, undercoats, which are designed to promote adhesion and provide a foundational layer, may need a different nozzle size or air pressure compared to topcoats, which are typically formulated for a smooth, aesthetically pleasing finish.

Technician B is correct in using different spray guns because the properties of the coatings (like viscosity, drying times, and chemical compositions) may necessitate different application techniques. Using the appropriate spray gun for each layer not only helps in achieving the desired thickness and coverage but also minimizes issues such as runs, sags, or an uneven appearance in the final finish.

In addition, using the right spray gun can facilitate easier cleanup and maintenance, as the residues from different compounds may require different cleaning procedures. Overall, Technician B demonstrates an understanding of the specific requirements for effective paint application in autobody work.