Q: lacquer "potting"?

[Helmholtz]

I can't comment on lacquer potted Fender PUs, because I haven't seen one yet (not saying there aren't any). But the '66 and '68 strat PUs I examined definitely were wax potted. The wax sometimes has a black or even blue hue.

In his book "The Fender Telecaster" A.R. Duchossoir shows a Fender factory blueprint dated Dec. 1965(revised 1967), which specifies the lead PU assembly procedure. Step 1: Core assy to be dipped in clear lacquer BEFORE winding. Step 4A: Dip in molten paraffin wax after wrapping with string.

Traditionally lacquer meant dissolved nitrocellulose. The nitro solvents are likely to melt the magnet wire insulation, when wet lacquer is applied to the coil.

[Telemachos]

I was referring to Stratocaster Pickups of that era. Late 60ies went w. lacquer. I've seen 72 Strat pickups that were lacquer dipped too.

[Helmholtz]

I was referring to Stratocaster Pickups of that era. Late 60ies went w. lacquer. I've seen 72 Strat pickups that were lacquer dipped too.

These observations:

I can't comment on lacquer potted Fender PUs, because I haven't seen one yet (not saying there aren't any). But the '66 and '68 strat PUs I examined definitely were wax potted. The wax sometimes has a black or even blue hue.

referred to strat PUs.

Late 60ies went w. lacquer.

Obviously not all of them.

[Joe Gwinn]

Although yes lacquer IS used on motor and transformer windings, those things tend to use much heavier gauge wire than a pickup does. So if the lacquer shrinks over time and tugs at the wire of a motor, the wire wins and the lacquer loses. In a pickup coil when #42 or #43 wire and lacquer-shrinkage duke it out, I gather that lacquer wins and the wire likely loses, hence the coil fractures I was asked to fix.

The "lacquer" used on motor and transformer windings is designed for the purpose, and doesn't shrink a lot. Motor windings are usually double-dipped, to ensure that the winding is totally solidified, so that mechanical vibration cannot cause the windings to rub against one another and eventually cause shorts. Also improves heat transfer out of the winding. Transformer windings are also double-dipped, if necessary. The magnet wire insulation is impervious to the solvents used in this kind of lacquer.

For #42 wire, I'd use one of the thin epoxy potting agents designed for such things. One coat, and no shrinkage. Use heavier wire for the leads, and embed then in the now-solidified winding.

[Possum]

P13's were lacquer potted. But these were air coils with no core. As I stated above, lacquer does not penetrate the coil, just a couple outer layers. This is how the vintage Tele neck pickups were potted.

[Joe Gwinn]

The "lacquer" used on motor and transformer windings is designed for the purpose, and doesn't shrink a lot. Motor windings are usually double-dipped, to ensure that the winding is totally solidified, so that mechanical vibration cannot cause the windings to rub against one another and eventually cause shorts. Also improves heat transfer out of the winding. Transformer windings are also double-dipped, if necessary. The magnet wire insulation is impervious to the solvents used in this kind of lacquer.

For #42 wire, I'd use one of the thin epoxy potting agents designed for such things. One coat, and no shrinkage. Use heavier wire for the leads, and embed then in the now-solidified winding.

One thing I forgot to mention: Epoxy potting of coils is often done in a vacuum chamber, ensuring total penetration of epoxy into the coil, which becomes solid as a rock.

[Rog_B]

I've only ever built Tele neck pickups with lacquer potting. It has always been fine. It's how they used to do it, not saying it's better but it works. I got the idea from some Ron Ellis pickups I had. They sounded great and are, for better or worse, a "cult" item.

I built quite a few Strat sets with lacquer dip and one set is on my #1 swamp ash/1-piece maple Strat and they are staying there. Lovely-sounding guitar, that one. I tried exactly the same wind with wax and I preferred the nitro. More open with cleans and I haven't found any problems with higher gain that a shuffle of the feet didn't cure.