TROUBLESHOOTING GUIDE — METAL SPRAY
SOLVENT POP IN THE BASECOAT
Solvent pop appears as small “pinhole” or crater-like defects in the basecoated surface. It occurs when the basecoat layer is applied too thick and dried too fast.
As the basecoat dries, a “skin” forms on its outermost surface. In the presence of excessive heat, solvents trapped underneath this skin force their way through, resulting in a solvent pop.
We purposely induced an extreme example of solvent pop by applying an excessive amount of basecoat to a practice tile, then drying the tile under intense direct heat from a heat lamp.
The solvents on the outermost surface evaporate quickly, causing a “skin” to form. The lamp’s intense heat causes the solvents trapped underneath the skin to flash into a gas. These gas bubbles burst through the skin, leaving a permanent crater or pinhole.
If you follow the recommended two-phase drying procedure as described in the Drying the Basecoat section, you will never have a problem with solvent pop.
After applying the basecoat, immediately place your parts in the warm space (with the heater turned off) and let them air-dry overnight — allowing the solvents to evaporate in a controlled manner.
The following day, the volatile solvents will have dissipated. Now you can turn on your warm space heater and bake-dry your basecoat with no risk of solvent pop occurring.