A look inside a Lane Poor MM5.

[Possum]

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Are the coils completely solidified?, It looks like it from the top, if they are he was using something water thin to pot the whole pickup, I've never encountered anything like that, maybe he vacuum baked them?

[belwar]

yeah they are nice and potted to the core, but not with wax, nor with the same black goop. I'm thinking its either bondable wire, or some form of laquer. I wonder if you could use an oven to bond the wire.. hmm

[David King]

They were vacuum baked.
Furnaces are used to fuse bondable wire.
Typically when AC motors are rewound they are dipped in a vat of varnish which is then baked for many hours until all the windings are fused together.
This varnish isn't like the wood coating varnish as it's all oil and resin without dryers or volatiles. It's the same stuff used to coat power transformers.

[Joe Gwinn]

I'd really like to know what the inner compound is. The outside IIRC was epoxy.

Joe, do you mean silicone rubber (I've never heard of silicon rubber)? If that's the case, how would you tell?

Yes. Burning will still yield sand.

I'm still looking for an RTV potting compound.

RTV is a silicone rubber. It's pretty easy to get, but one must go to a plastics supplier.

[Possum]

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Micromark has RTV silicon mold stuff and any jewelry supply place will have the baking type and RTV, there are many kinds of the stuff. I used a see through silicone mold material that you baked so you could see when cutting the mold apart without damaging the wax model.

Lacquer makes a really crappy potting liquid, it doesn't penetrate more than a few layers deep, probably why Fender only used it a short period, plus on some insulations its like putting an expiration date on it because it will degrade the coating, I've rewound a fair amount of vintage Fender ones like that. It does have a unique tonal thing going though.

[David Schwab]

Fender still uses lacquer on the bass pickups.

I use vanish. I don't have a vacuum setup yet, but it does get all the way to the inside.

And vanish and plumbers tape work really well together.

[Joe Gwinn]

Typically when AC motors are rewound they are dipped in a vat of varnish which is then baked for many hours until all the windings are fused together. This varnish isn't like the wood coating varnish as it's all oil and resin without dryers or volatiles. It's the same stuff used to coat power transformers.

The traditional varnish for motor and transformer windings is Glyptal Home Page.

Motor windings are dipped and baked twice, to ensure that the windings are mechanically solid and so won't fret (and thus short) from vibration while running.

Transformers are usually dipped once, unless intended for severe vibration service, in which case they too may get the double dip. Small high-voltage transformers (such as TV flyback transformers) were sometimes double dipped as well, to eliminate all voids where corona discharges could happen.

Glyptal is and was also used as a threadlocker, long before loctite was invented. Glyptal is a dark red color, and you often seen fasteners in electronic equipment daubed with glyptal so they won't loosen in use.

GC sells Glyptal in small bottles for touch-up and repair.

[Possum]

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You use "vanish?" Is this paint on stealth material? Did it? They still use lacquer on bass coils? On poly coils its probably not a problem, PE though are the dead ones I've seen too many of.

[Mike Sulzer]

Motors and power transformers are subject to high temperatures as well as vibration. The varnishes, etc., are designed for this type of environment. If pickups need to be potted, is the usual mixture of waxes not good enough?

[David Schwab]

If pickups need to be potted, is the usual mixture of waxes not good enough?

I don't want to deal with wax, and varnish works great.

Some pickups are potted in lacquer, and Rick Turner uses shellac, so I figured why not varnish?

[David King]

I think the issue here is that longer coils will see some significant stretching and shrinking due to ambient temp changes. If you encase the wires in something solid you have a higher probability of failure over time as the wire can no longer slide around a little as it reacts to temp changes.
Wax works but it clearly changes the tonality of the pickups in some cases according to folks around here. The question is whether there is a happy medium, a goop that's stiff enough to keep the sonic purists happy and gummy enough to keep the wire from breaking when the guitar spends 10 hours in the hold of a transatlantic flight at minus 20º and then gets warmed up to 105º at the other end of the trip...

[belwar]

Motor windings are dipped and baked twice, to ensure that the windings are mechanically solid and so won't fret (and thus short) from vibration while running.

That would explain why Lane baked the pickup twice..

Glyptal is and was also used as a threadlocker, long before loctite was invented. Glyptal is a dark red color, and you often seen fasteners in electronic equipment daubed with glyptal so they won't loosen in use.

GC sells Glyptal in small bottles for touch-up and repair.

The wire is relatively dark red. It looks like motor windings. It looks darker than standard polysol. Can you tell me what GC is ?

[David King]

SPN soderon is red. I'm pretty sure that's what this wire was. I doubt very much that any Glyptal was used in these pickups. That stuff makes a mess and stinks to high heaven. It's intended to penetrate larger wire gauges and fill the voids between them, much too thick to get through a 42 awg coil I bet.

Lane baked twice because the first bake solidified the windings and the second bake solidified the black epoxy shell. There were never any injection molded shells, too many shapes to recreate.

[Joe Gwinn]

The wire is relatively dark red. It looks like motor windings. It looks darker than standard polysol. Can you tell me what GC is ?

GC is GC Electronics, a widely distributed distributor of chemicals for electronics.

This is not glyptal, but it's a varnish for another purpose: GC Electronics - 10-5002 - Allied Electronics

GC may no longer carry glyptal.

A call to the Glyptal Corp should yield a lead. Glyptal 1201 appears to be the original Glyptal.

[Possum]

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If he was baking it for the coil then its obviously bondable wire. I wonder what temp that stuff fuses together. I think I had a Korean pickup I took apart once that was bondable and it was on a plastic bobbin so couldn't be too hot....