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Potting Ideas

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Patrick

Fri Jul 09 2010, 01:24AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

what do you mean dissolve? does the wax help melt the glue sticks, then the glue sticks are poured on to the target device?

or,

does the wax and hot glue get poured into the target device?

quicksilver

Fri Jul 09 2010, 02:20PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Use the glue sticks straight from the gun (hot) and use something like a small paper cup with some wax in it. The hot (HOT glue) will then melt the wax - and you stir. I tried it. I found that the hot glue that is NOT translucent is best (the flat opacity type). Once mixed completely; then you pour it into what you have.

803

Fri Jul 09 2010, 02:39PM

Registered Member #2807 Joined: Fri Apr 16 2010, 08:10PM
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Posts: 191

realy? I would think the wax would be hotter than the glue.

IntraWinding

Fri Jul 09 2010, 07:20PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

How much do the glue sticks increase the viscosity of the mix compared to pure wax?

Patrick

Fri Jul 09 2010, 08:32PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

ok i will try this with my mother's "tea light" candles, and some of my hot glue sticks.

quicksilver

Sat Jul 10 2010, 06:58PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

When I tried it I had two basic "types" of hot glue. One was translucent and did not work that well. That type has moderately stronger and hotter features than the flat off-white type. But it's the flat white that works well. I simply got a paper cup put some candle wax within and used the glue-gun to drip the hot glue onto the wax. You need to mix it quite well, however.
It was hot enough to melt it. But you're correct in assuming that you need to keep it hot or use it ASAP because it will melt the wax and solidify within about 10-15 seconds. I used the paper cup to pour the material as it was convenient to make a "spout" and pouring neatly into what I needed to cover. A hot water bath (near boiling) will barely keep it at liquid point.....You have to prep your insulation project & go for it.

"How much do the glue sticks increase the viscosity of the mix compared to pure wax?"
Assuming you're using candle wax/bee's wax: my opinion about 50% when hot and pouring as compared to either the liquid hot glue alone OR the wax. It would be interesting to try a heavier form of wax but then I think you're spending $ & that defeats the purpose.

Sulaiman

Sun Jul 11 2010, 08:13AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

For hobby use it's best not to pot anything if possible - any part may need replacing!
sometimes several dips in polyurethane varnish is all I need,
If something needs potting then I like plain candle wax which is hot and shrinks on cooling and is soft, has loads of problems BUT it can be easily removed/re-applied,
for a guaranteed first-time-working option
(e.g. one bag of the part I mentioned above would be enough for 3" x 1.5")

- low viscosity mix-in-the-bag 2-part potting compounds are the best I've ever used.

If I had a useful vacuum pump I think that my answer would be different.

IntraWinding

Sun Jul 11 2010, 08:57AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Here's a quote from Wikipedia:

Pure Paraffin Wax is an excellent electrical insulator, with an electrical resistivity of between 10^13 and 10^17 ohm metre. This is better than nearly all other materials except some plastics (notably teflon).

But I think most plain white candles are a mix of Paraffin Wax and Steric Acid (Octadecanoic Acid). Apparently Steric Acid is also an insulator (which surprises me since I thought acids where ionic conductors) but since I can't find anything as specific as the quote above about Paraffin Wax, I'd feel on safer ground with pure Paraffin wax. Apparently it comes in different hardness grades too. You should be able to buy it as supplies for the candle making hobby.

...

Sun Jul 11 2010, 05:29PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

One word of warning with hot glue--some of it is slightly conductive (this is relatively easy to test for), but some of it also causes havoc at high frequencies. I am not 100% sure of the mechanism, but I have had several projects which were working fine before hot gluing them into a project case to find the circuit has stopped working. I suspect that it has a high dialectic constant, although I never did track down exactly what the problem was.

quicksilver

Sun Jul 11 2010, 05:47PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Apparently there are several "hot-glues" and they have differing dielectric constants. I had used the translucent type on a flyback that "jumped" it's arc from pin to pin and it didn't insulated that well at all. {What's more that type is tougher and more of a pain in the ass to pull off.} That is also where I learned a lesson about silicone sealant or caulking. I used a acetic acid type of common caulking (stunk like vinegar) & noticed that after several day the adjacent pins did suffer for it. Had they not been thick there would have actually been an issue of sever corrosion.

There is a "red paint" type insulation available at electronic stores that is very effective. But it's quite pricey. Occasionally I find that I can get by with something that has a relatively thin but effective barrier & need not pot the thing.
I was making a toy from a HV unit (from a laser-printer) & had thought of potting it. But then if a little thing goes (like a resistor from higher input current) you can't fix what would have been a two minute job. I once made a coil with a ferrite bar that took several hours of winding super fine wire. It worked and I potted it fast as it was delicate "naked" & you can better organize the leads with potting.

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