Patent ID: 7648603

Claim:
A method of joining PVC or CPVC plumbing pipes, comprising: applying a primer composition to plastic plumbing pipe joints made from PVC or CPVC to condition the joints, wherein the primer composition is formulated to comply with the NSF 61 standard for safe drinking water system components and comprises a solvent component comprising a combination of between about 5 to about 15% (w/w) tetrahydrofuran, between about 5 to about 15% (w/w) cyclohexanone, between about 35% to about 45% (w/w) of acetone and between about 35% to about 45% (w/w) methyl ethyl ketone and a colorless dye component that appears colored when illuminated with black light; applying adhesives to the pipe joints; and joining the pipes with the adhesive at the joints, the primer composition formulated to appear colorless under incandescent and fluorescent light, and appearing colored under black light.