Cheap potting compounds?

[Whales]

I also didn't know 'caulk' could be specific in another context.  The verb 'caulking' in particular feels like a "squishing anything out of a tube" word and I probably mentally extend the noun from there.

Acrylic paint does not re-dissolve after it has dried, but I don't know how conductive it is or if it does something nasty like trap water.   Pros however: easy to apply, easy to see any areas you have missed, washes up afterwards with water.

[yamajason]

I know you are in England but this stuff is outstanding and is extremely cheap compared to the electronic branded stuff. His site is extremely informative on all epoxies.   

http://www.ebay.com/itm/EPOXY-RESIN-CIRCUIT-BOARD-POTTING-COMPOUND-WATERPROOF-MASKING-SEALANT-96-OZ-KIT-/310368256789?pt=LH_DefaultDomain_0&hash=item484363c315

Price: $43.43
Shipping: $73.39
Lol

That is 3 quarts for about $39.00 a quart including shipping.

This MG chemicals on Mouser works out to 89.40 per quart before shipping

What do you think about adding Aluminum Oxide Pigment to increase the Thermal Conductivity of the Potting Compound?  Got the idea from MG Chemicals 832TC Thermally Conductive Epoxy Encapsulating and Potting Compound
I am not sure how much to add or the ratio?

[Cliff Matthews]

Pity, this stuff seems cheaper this side of the pond. http://www.amazon.co.uk/MG-Chemicals-Encapsulating-832B-375ML-components/dp/B005T8PYZ4

[Chris Wilson]

This is what I am using currently, I have it down to a fine art and 500 grammes pots ten of my circuit boxes, so I build ten at a time.

http://uk.rs-online.com/web/p/potting-compounds/1991430/

[yamajason]

Found that you can add Calcium Carbonate Powder to increase Thermal Conductivity of the Potting Compound
see http://www.ebay.com/itm/EPOXY-FILLER-LOW-COST-EXTENDER-HIGHER-THERMAL-CONDUCTIVITY-ELECTRICAL-RESISTANCE-/220513516394?rd=1
http://www.ebay.com/itm/EPOXY-RESIN-CIRCUIT-BOARD-POTTING-COMPOUND-WATERPROOF-MASKING-SEALANT-96-OZ-KIT-/311412419001?

[unitedatoms]

Just to warn you. I worked at factory with batteries for military robots being potted into compound. The process was cheapest possible, but nevertheless, the guys who made potting put together the separate shack outside the main building to keep fumes away from people.

The epoxy was some very runny black liquid. Stay away of it by all means. It will ruin your health

[tehmagicsmoke]

Don't know if it will suit your purpose but clear spray paint or clear nail polish may work. And if you can get it I have seen liquid electrical tape in the clear flavor, I think for about $10 for a small container about 6oz.

[Munsterfield]

Regarding potting electronic components, I'm really curious about masking off areas such as what Falcon69 did on his boards, by creating molds.  Falcon69, if you are still following this thread, what was your experience in that mold that you created?  What worked?  What didn't?  What material are you using for the mold, and what are you using for the potting compound?
Thanks!

[Raj]

There's something called reenterable potting compound

[Smokey]

What are you guys using these days for potting compound?
It looks like I'm going to have to pot in a couple hundred little modules so I'm looking for something inexpensive that is hopefully also in stock somewhere and doesn't have a terribly involved mixing/dispensing process.

[wraper]

There are electronics grade neutral silicones. However they come in 300+ ml tubes which are very expensive, and usually you'd waste most of it due to short shelf life. However you can buy 70x (701-708) electronics grade silicones in 45ml tubes from China. They have different properties such as viscosity, self leveling and strength but all are very good IME. 708 type is the most interesting IMHO, and is what I suggest for fixing capacitors to PCB. It has quite low viscosity, even lower than most semi-flowing silicones, so easy to apply, however it does not flow by itself at all, so will stay exactly how you applied it. For potting something  use 701-705 which flow/self-level. I suggest placing them in moisture barrier bag with dry silicagel pouches (of which you should have plenty if order components from major distributors), rolling an open a few times and and fixing closed with clothespin or something similar. It will prevent curing thus extending their life many times.

[Smokey]

For the units I'm looking at now, there is a little less than 14mL that needs to be filled.
If I get the 450mL tubes of something like this(MG 832B) for about $60, then that's about $1.86 of epoxy per product. 
https://mgchemicals.com/products/potting-compounds/epoxy-potting/black-epoxy/

That's sort of my price to beat at this point.  While I know it's more expensive, I do like the self mixing tube dispenser for the listed product.  I'm not sure how much I should worry about the mixing dispensing process from a cost/labor standpoint.  I would probably have my CM do the potting and anything that has an involved process is going to increase the cost.