cheap fluid potting compound - Page 1
Forum section: electronics / projects

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: February 29, 2016, 12:39:18 pm
content: Does anyone have any ideas or views on a cheap runny potting compound?Back in the 80s I used potting compounds regularly- mainly slate-loaded epoxy which was a very hard and permanent system, but also some rubbery compound whose name I forget. If I needed a plain epoxy I would visit the electricians workshop and rob some black stuff from a cable-jointing pack.These days I have occasionally used neutral-cure silicone sealer for personal projects.Recently I seem to have had a shoal of ignition modules from 80s and 90s American outboard motors to repair. I need a source of cheap fluid potting compound that is preferably a similar consistency to silicone seal when cured but fluid when mixed to pour into the case.What about hot-melt glue sticks?I have searched EEVblog- RayTech Magic Gel looks wonderful, but the price is way beyond 'hobby' level.Regards, BT.

author: ruffy91
author_rank: Regular Contributor
timestamp: February 29, 2016, 01:01:41 pm
content: The RayTech Gel doesn't really seem to be that pricey.just look at how much potting compound you need, most of the times you can get away with 50-100ml for something like a ignition module.In such an environment something like this:http://www.electrolube.com/products/polyurethane-epoxy-resins/er2162/resins_epoxy/seems reasonable, you can get it in 250g packs. Most of the resins from Electrolube cost about 15-25$ in 250g packs. There are also special variants for maritime and high-temperature usage and usage near fuels.I don't think you can use something like hot-melt glue for potting, I doubt it will conform to the components. Most probably it will turn brown before it's hot enough to be runny.Edit: As an alternative use colorless 2-Part epoxy resin, which is used to laminate fiberglass, 1kg with 0.5kg curing agent should cost about 20-30$.Do not use anything black, as it will most probably be electrically conducting (carbon black is used for the color).

author: RobertBG
author_rank: Regular Contributor
timestamp: February 29, 2016, 09:43:52 pm
content: I've used Polycraft clear resin on several projects with good results.I wanted a clear end product so that limited my choices some but I think it would work well for your needs.http://www.mbfg.co.uk/polyurethane-casting-resin/sg2000.htmlChances are you can find something similar locally.

author: Someone
author_rank: Super Contributor
timestamp: March 01, 2016, 12:22:36 am
content: Quote from: ruffy91 on February 29, 2016, 01:01:41 pmThe fibreglass epoxies tend to be exothermic, setting 100g in a solid block can emit smoke and be rather unpleasant.

author: Unknown
author_rank: Unknown
timestamp: March 01, 2016, 12:42:06 am
content: Chemtools PCT-7000? Pours well, sets like hard silicone, reasonably cheap. Should be available or orderable through your local fastener/engineering/fabrication supplies places, but IIRC Altronics has small packs at not-too-exorbitant prices.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: March 01, 2016, 06:25:57 am
content: Thanks for the info-I wanted to avoid a compound that was rock hard as I worry about expansion damaging components, plus it is near impossible to remove in the future.I hadn't thought about the exothermic properties of resins- I remember casting a prototype inlet manifold years ago which got VERY hot indeed!The Magic Gel looks like AU$200/litre from the UK which is too expensive for hobby use.Thanks Xilef for the info on the Chemtools product- it looks good, and $27 isn't the end of the world + free shipping too.A quick story about the slate powder-loaded epoxy of yesteryear- My colleague and I wanted to de-pot a commercial module to repair and clone it. A rep for a chemical supplier reckoned that he could supply some chemical that would dissolve epoxy so we ordered some. We dunked the module and left it over the weekend. We rolled excitedly up to work to find a grey goop in the bottom of the container, and a wavy glass fibre mat with chips and foil and carbon bits standing on legs. We looked at each other and burst out laughing- "That went horribly wrong..." my colleague observed.BT