Encapsulating Epoxy

[SpareRibs]

Hello,
Could someone please tell me what type and where to obtain epoxy to encapsulate pickups, I know excessive expansion, contraction, and heat created in the chemical process of curing can cause damage. I am at a loss with the descriptions of some of the products, as they are not produced with guitar pickups in mind.
Thank You in advance for any help provided.

[rhgwynn]

http://www.ebay.com/itm/EPOXY-RESIN-...-/310186942108

David Schwab knows, he uses it all the time.

-Rob

[Bruce Johnson]

I encapsulate all of my pickups with West Systems epoxy, using the 105 resin and the 206 Slow Hardener. With the slow hardener, it doesn't build up any noticeable heat. It takes 6-12 hours to cure.

Here's an older series of pages showing my whole pickup making process, if you haven't seen it already:

Building Scroll Basses- Pickups 1

[SpareRibs]

Hello,
I would like to thank both of you, now at least I know more about the type of epoxy I am looking for. When I just look up epoxy I get swamped with all the different types with a lot of information pertaining to marine applications or how to apply it to space modules and the like. I had not thought to ask pertaining to electrical applications, that narrows the search a lot. Thank You once again.

[David Schwab]

Epoxy Resin Circuit Board Potting Compound Casting 48oz | eBay

David Schwab knows, he uses it all the time.

-Rob

Wow, that's cheap. I use this:

832B 3L Epoxy Black Encapsulating and Potting Compound | eBay

They sell smaller kits as well.

MG Chemicals 832B 375ml Black Epoxy Encapsulating Potting Compound in 2 Parts | eBay

But they aren't worth it for the amount of pickups I do.


I tried some cheaper epoxy once from Aeromarine Systems. This is what I ended up with:



My advice is thoroughly test what you buy.

[David King]

Cool, looks like a whammy bar on the pickup. How long did you mix that stuff for? Must have been a mess to clean up.

If I were potting a lot of pickups I'd want a system like the mixing tip caulking guns. TriggerBond® Dispensing System ? Adhesives & Potting Compounds

[Bruce Johnson]

I've been encapsulating my pickups with the West Systems for about 8 years now, and I don't remember ever having any type of failure like non-cure or cracking. It seems to work just fine for that job. I use enough of the West Systems all around my instruments that I buy the gallon kits, which are about $140.

What is it about the commercial "electronics encapsulation" epoxies that makes them better, and worth all that extra money? I'm just curious. Some years back, when I worked in an electronics lab, we used the commercial stuff (I think it was 3M) with the little spiral tip mixing guns. And we frequently had non-cure failures, which were a real mess to clean up the boards and parts. The epoxy had a really short shelf life and it was very fussy in the mixture.

[David Schwab]

Cool, looks like a whammy bar on the pickup. How long did you mix that stuff for? Must have been a mess to clean up.

If I were potting a lot of pickups I'd want a system like the mixing tip caulking guns. TriggerBond® Dispensing System ? Adhesives & Potting Compounds

I mixed it for at least the time specified by the maker. I even called them and he gave me some tips for a way of mixing it, which is totally unnecessary for any other brand of epoxy I have used. Like Bruce said, most just work. The weird part is I did a bunch of pickups from the same mixed batch of epoxy, and most were fine, but somehow this one had a section that didn't cure.

Uncured epoxy cleans right up with isopropyl alcohol.

[David Schwab]

What is it about the commercial "electronics encapsulation" epoxies that makes them better, and worth all that extra money?

Don't know if it's better, but the MG epoxy is nylon filled, so it doesn't shrink, not that I've had a problem with that.

I've used West System epoxy for gluing basses together.

[Hugh Evans]

I worked in the adhesives and sealants industry for a number of years and have a suggestion that could be very useful to anyone potting coils with epoxy. Check out Titebond 531 (avoid 531+ as it will kick over too quickly and is a bit more of a challenge to emulsify as well.) It is available in both quart and gallon containers, yet it is much less expensive than most other epoxies. The reason for the lower cost is simple: Since it is marketed as moisture control product to decrease vapor transmission through concrete floors prior to hardwood installations there is no need for UV inhibitors... and UV inhibitors are bloody expensive to say the least. I've even known a few kayak builders who use the stuff for their initial sealing coats and use the higher-end UV resistant stuff from West System on the last couple of coats, which literally saves hundreds in a typical build.

If anyone is interested in a proof of concept test, I'll make a couple of calls and get a sample of it. Off the top of my head I believe a one gallon kit costs around $70 to $80. Of course, these can be kept separate and mixed in smaller batches as well.

[David Schwab]

If I were potting a lot of pickups I'd want a system like the mixing tip caulking guns. TriggerBond® Dispensing System ? Adhesives & Potting Compounds

Those look very cool, but they even say it's for small potting applications. Even with the biggest tube they have, you might only get a few pickups.

I've seen video of Duncan's factory where they use a similar mixing nozzle, but with larger containers of epoxy. It might be similar to that company's "Shot Gun" system.

Check out 3:06 in the video.

I also have to say I have never gotten all covered in epoxy. It's not that messy. I use a scale to mix in a single plastic cup, and after mixing it and letting it sit for 30 minutes (as per the instructions to let the air bubbles rise to the top). I usually mix up two cups, and then I put it into a plastic squeeze bottle (one at a time) and get to work. I try and do about six or more sets of pickups at a time.

[Joe Gwinn]

Those look very cool, but they even say it's for small potting applications. Even with the biggest tube they have, you might only get a few pickups.

I've seen video of Duncan's factory where they use a similar mixing nozzle, but with larger containers of epoxy. It might be similar to that company's "Shot Gun" system.

I also have to say I have never gotten all covered in epoxy. It's not that messy. I use a scale to mix in a single plastic cup, and after mixing it and letting it sit for 30 minutes (as per the instructions to let the air bubbles rise to the top). I usually mix up two cups, and then I put it into a plastic squeeze bottle (one at a time) and get to work. I try and do about six or more sets of pickups at a time.

I worked in a plastics lab in the late 1960s, as a summer employee. We were gluing the electronics of the moon lander together. That technician would not have lasted. The process was weigh components out into a plastic mixing bowl, mix thoroughly by hand, vacuum degass, put a small sample in a little aluminum foil cup and bake it at 180 F for 5 min, verify that the sample cured. If OK, pour the mix into an applicator and proceed.

Even with NASA-qualified materials, we would have a cure failure a few times a week.

As for the spiral-in-tube mixer, I've had problems with bad mixes and cure failures. I think you have to discard the initial mix output to get to the well-mixed stuff, so for small batches this would be very wasteful. The mix in cup approach will work better. Just buy slow-cure materials, so one need not be rushing about.

[Tom Phillips]

...That technician would not have lasted...

It's a shame that they goofed up the video with the ridiculous "before" method scenes. Bad marketing if you are targeting intelligent people.
However, thanks for posting the video. It was interesting to watch. Systems like that seem to be advantageous when the labor costs would far outweigh the cost of the material and the mixing tips.
Regards,
Tom

[David Schwab]

I worked in a plastics lab in the late 1960s, as a summer employee. We were gluing the electronics of the moon lander together. That technician would not have lasted. The process was weigh components out into a plastic mixing bowl, mix thoroughly by hand, vacuum degass, put a small sample in a little aluminum foil cup and bake it at 180 F for 5 min, verify that the sample cured. If OK, pour the mix into an applicator and proceed.

Even with NASA-qualified materials, we would have a cure failure a few times a week.

As for the spiral-in-tube mixer, I've had problems with bad mixes and cure failures. I think you have to discard the initial mix output to get to the well-mixed stuff, so for small batches this would be very wasteful. The mix in cup approach will work better. Just buy slow-cure materials, so one need not be rushing about.

Oh, well I guess I'm doing it the right way then. I basically do the same thing, I pour in the hardener and resin, which is 1 to 2 parts, and I do it by weight. Then I hand mix for a good five minutes. Then I let it sit for 30 minutes to degas, and then pout it into the squeeze bottle.

It's slow curing epoxy. Takes 24 hours at room temperature.

[Joe Gwinn]

Oh, well I guess I'm doing it the right way then. I basically do the same thing, I pour in the hardener and resin, which is 1 to 2 parts, and I do it by weight. Then I hand mix for a good five minutes. Then I let it sit for 30 minutes to degas, and then pout it into the squeeze bottle.

Yes, but there is one missing step - the little sample in the cup, cured at 180 F before using the batch.

I always do something equivalent, or at least keep the mixing board, so I can tell if I've a bad batch.


Even if I'm not making stuff that will go to the Moon.