Quick quiz – what is going on in this picture? Important clues include air masks, rubber gloves, two guys squatting around a partially filled neck mold like a couple cub scouts taking a break around a camp fire, Nate’s phone inside a plastic sleeve running what looks like a music app, a wire connecting the phone to the black box under the neck mold.

Here is another hint – the black box under the neck mold with the wire plugged into it is a compact amp/speaker.

Okay, so yes this is a Ridgewing neck being molded, and the black goo is West System marine epoxy with a lot of carbon black mixed in that forms the matrix of the neck. But why are Nate and Jay just sitting there looking at it? The answer is bubbles, those cursed enemies of molders everywhere. Music is being played from Nate’s phone to the amp under the neck mold loudly enough to vibrate the liquid epoxy. This reduces the viscosity of the epoxy immediately in contact with the bubbles and allows them to float upward, away from the back of the neck. Dirty little secret: It is OK to have bubbles in the epoxy of your finished neck, even lots of bubbles, as long as you can’t see them. Suitably encouraged by the musical vibrations, any small bubbles in the black liquid epoxy only have to float upward a couple of millimeters to disappear forever.

After a suitable wait, the mold continues to be filled. A fairly massive carbon fiber beam incorporating a 2-way adjustable tension rod is laid in and more epoxy is added until the mold is slightly over-filled. When the mold box is closed and clamped, the excess epoxy is forced to ooze out through a network of sprues surrounding the part in the mold. Just in case the sprues get over-filled, the mold is equipped with a couple of plastic tubes extending down through the lid through which the excess epoxy can escape.

At the lower left in the mold box is a fixture for directly molding into the neck the brass-lined holes which will receive the headstock’s mounting pins. The two vertical threaded rods visible in the mold box support a simple fixture where two horizontal brass sleeves are fitted over a pair of precisely-spaced stainless steel dowels. When the cured neck is taken out of the mold, the twin dowel fixture is pulled out, leaving a pair of shiny brass-lined, perfectly dimensioned and perfectly aligned headstock mounting holes.