potting and inductance

[Rosewood]

Does potting a pickup affect inductance? If I had a meter I would just test it. I do remember one of the first coils I wound I potted in shellac and it was darker sounding to me, maybe the shellac was not dry inside. I haven't compared a before and after with wax but surely there's more going on than just loose windings.

[Possum]

No it doesn't affect inductance but it does affect other things. When you embed a coil in a substance the major thing is the dielectric rating of what its embedded in. Wax is around a 3 rating, this is for paraffin, just quoting from memory. 3 is pretty low so minimal effect. Pure bees wax has a bit higher rating so you get more interference between each strand of wire, so maybe a tad darker tones. Shellac potting is confusing alot of hobby winders out there; I read on some website a guy claims he has a secret shellac and "other ingredients" that gives a "vintage tone." When you pot with shellac what happens is the outer layers dry first and seal the inner layers from drying out. Shellac has alcohol and water in it, both which have a high dielectric rating, so it shorts out some treble frequencies, which sounds really great. Trouble is, six months later the coil finally manages to dry itself out and all those effects disappear. And yes you're right about potting stabilizing the wire in an unpotted coil. Basically the other thing that happens when you pot a coil is you solidify the windings so they can't vibrate on their own, otherwise known as "microphonics." This is good and bad. Some vintage pickups don't sound right if they're NOT microphonic, P90's and PAF's are the best known. But you can partially pot coils by not leaving them in wax too long. Old P90's and PAF's weren't potted in the factory BUT over a time of aging, they have an unintentional form of potting, because the adhesive from the paper tape turns into sticky goop and seeps into the coils a slght bit enough to change microphonics a little bit. My advice is don't listen to what anybody says on this subject, write down as many ways you can think of to test what different ideas you have and test each and every one of them. Thats the only way you'll find your own truths and what works for you.

[Rick Turner]

Dielectric plastics (Barry L. Ornitz)

Good old Google...

Seems like paraffin is indeed one of the best potting compounds you can choose...if you so choose...for its low dielectric constant.

I used to use shellac, but I've mended my ways.

[David Schwab]

I use paraffin now as well. I actually use one of those paraffin warmers made to stick your hands in. The paraffin is mixed with paraffin oil, so it doesn't get too brittle.

[LtKojak]

I use paraffin now as well. I actually use one of those paraffin warmers made to stick your hands in. The paraffin is mixed with paraffin oil, so it doesn't get too brittle.

Do you know why it's considered good a mix of paraffin and bee wax to pot p'ups? I think the source was some article about potting by Lindy Fralin...

[Rick Turner]

Bees' wax has a higher dielectric constant than paraffin so the pickup will have higher capacitive losses...if that's what you want. Less highs...

[big_teee]

I use paraffin now as well. I actually use one of those paraffin warmers made to stick your hands in. The paraffin is mixed with paraffin oil, so it doesn't get too brittle.

I do wax potting nearly the same.
I use Pure Canning wax, and add a little pure unscented Paraffin Lamp oil.
That keeps it pliable.
I've taken a lot of old pickups apart and it looks to me like just old brittle wax is what the imports use.
The imports like to fill everything up with wax.
I pot mine about 10 minutes and try to drain all the wax off as possible.
When doing humbuckers I do pot the p/u after it is totally assembled without cover.
I do some finally Nylon taping after it cools.
Don't know if I'm doing it right but thats how I do things.
I also like the wax around 150f.
If it is cooler than that it doesn't seem to do as well.
Terry

[David Schwab]

I wrap some paper tape around the bobbin first, but it's narrow so it doesn't cover the whole thing, but secures my finish wire. Then I put a rubber band around it and drop it in the wax for 10 minutes. I let it drip a bit when I remove it, and then squeeze any extra wax out with a paper towel and let it cool down. The wax goes all the way to the center of the coil, and it's not to much. You almost can't tell it has been potted by looking at it, unlike those import coils. After it's cool I use some wider paper tape to cover it up.

[J M Fahey]

Do you know why it's considered good a mix of paraffin and bee wax to pot p'ups?

The mix is less brittle than either of them.
I reload gun cartridges and have tried a ton of different mixes as lead bullet lubricants, (even some "Far West" types based on tallow), including many based on paraffin.
Paraffin alone ends up being too brittle, specially on cold days; wax is more forgiving, besides smelling really good. (real beeswax, that is).

[big_teee]

The mix is less brittle than either of them.
I reload gun cartridges and have tried a ton of different mixes as lead bullet lubricants, (even some "Far West" types based on tallow), including many based on paraffin.
Paraffin alone ends up being too brittle, specially on cold days; wax is more forgiving, besides smelling really good. (real beeswax, that is).

I had a hard time finding the Canning Paraffin.
I don't have a clue where to buy bees wax.
Did you try the Lee Liquid bullet lube.
I use to coat my muzzle loading bullets with it.
I went to Sabots the lube to messy!
Terry

[Rick Turner]

I melt in a crock pot. Use the same paraffin wax used in some of the home canning methods. I also use a vacuum chamber to assure getting the wax into every last nook and cranny. Another trick...remove the handle on the lid of a crock pot and replace it with a vacuum fitting. Then get or make a rubber seal for around the lid. The ceramic crock pot itself becomes the vacuum chamber.

[big_teee]

I melt in a crock pot. Use the same paraffin wax used in some of the home canning methods. I also use a vacuum chamber to assure getting the wax into every last nook and cranny. Another trick...remove the handle on the lid of a crock pot and replace it with a vacuum fitting. Then get or make a rubber seal for around the lid. The ceramic crock pot itself becomes the vacuum chamber.

I tried the double and triple potting, and I think you can over do it.
I really don't mind if it doesn't get all the way through the coil.
I do want anything loose on the surface to be incapsulated and nailed down, so to speak.
So do we really need it vacuum potted?
I put mine in the wax pot, and shake the pickup around every minute or so, and when the last bubbles are gone, I take it out.
I drain all the wax off that will run off, then when it cools, I wipe off the wax from anything that is going to show.
Terry

[David Schwab]

I had a hard time finding the Canning Paraffin.
I don't have a clue where to buy bees wax.
Did you try the Lee Liquid bullet lube.
I use to coat my muzzle loading bullets with it.
I went to Sabots the lube to messy!
Terry

Amazon.com: Paraffin Wax Refills - Unscented - 6 lb pkg: Beauty

[J M Fahey]

Hi bigtee/Terry.

I had a hard time finding the Canning Paraffin.
I don't have a clue where to buy bees wax.

I think "canning paraffin" is plain paraffin by other name.
The only difference between different batches is the melting point, which if I don't remember wrong is around 59ºC.(better Google it) There is a small variation in commercial samples, not more than 2 or 3ºC.
There are *many* shops in Buenos Aires which cater to "healthy people" which sell natural honey, beeswax and other bee products, try the equivalent US version, not the "health food" section in a Supermarket but rather some Mom and Pop or Health nut small shop. At worst, they can order it for you.
I use Lee equipment but Alox Liquid Lube is hard to find here, I mix some Molykote paste into it (excellent) or at least some graphite powder.
Messy is part of the fun ... or so they say ¿¿¿¿????
Thanks for the vacuum pot tip, I'll try it.

[jason lollar]

thats funny i have the same set up Rick turner describes but I use a piece of 1/2" lexan for the lid with a vacumme fitting screwed into it- 10 seconds to 1 minute 30seconds is all it takes wwith the vacumme and its ver consistant- pick your time setting for whatever level of potting you want.
Wax helps hold fender pickups together and it keeps the coil from shifting if it getrs bumped- thats a problem with alot of vintage pickups "my pickup became microphonic all of a sudden" We did a story on it in our blog about other aspects of potting.
Even 10 seconds in the opotter will help keep the coil from shifting down the road and you still have plenty of the good microphonic sound.
Oh- you can buy one of those medical vacuum pumps they use for- pulling beans out of kids noses or sucking out ear wax?? I dont really know what they use them for but there are always alot of them on ebay.