Tiny holes in the finish caused by surface porosity or other imperfections in the substrate. Pin holing is sometimes confused with, or inaccurately described as, solvent popping.
Imperfections in the substrate
Substrate surface porosity
Insufficient amount of reducer
- Clean surface with Awlgrip Wipe-Down Solvent (NA/AP: Awlprep T0008 or Awlprep 400 T0170; EU: Surface Cleaner T0340).