Bonding epoxy to PVC for water proofing

Thanks Ed, this stuff is too small to abrade manually. The wires cores are ~0.3mm diameter.

I did read that to seal some potted sonar assemblies a couple of tight large section o-rings are placed on the cable inside the potted volume.

The o-ring material is selected to bond well to the potting material.

The theory is the o-ring tension provides a seal against the cable sheath and the potting compound to o-ring bond seals the ingress path around the outside.

It sounds viable but I'm a little skeptical about long term sealing.

I needed to contain internal pressure that expands the O ring while you have external pressure compressing it. It sounds like you found a proven solution.

10 meters deep is the same pressure differential as a vacuum, which these are thick enough to resist:

nk I read that somewhere. But you can find epoxy that will adhere sold for glueing copper plumbing together.

bonding to surface oxide. Depending on the metal and the thickness and natu re of the oxide, this results in weak joints in stainless steel, aluminum, copper alloys, and, of course, anything containing lead. There are other pr oblem metals.

le it's coated with the mixed epoxy. This is sometimes called "scratch-in" preparation. I use it all the time, and it works great on stainless and alu minum.

I never tried it or looked into it, but I suspect it will be the same as f or other metals.

aluminum aircraft wing skins being a prime example. To work fast and to get more reliable results, industrial users have worked out various conversion coatings and etches for specific metals that need to be bonded with epoxy and other adhesives. On aluminum, for example,they use phosphoric acid anod izing, PAA, and I've heard there are newer, better conversion coatings for aluminum.

st call 3M or Loctite, or whomever, and ask to speak to an engineer. Or I d id. I was a trade magazine editor and I could use that leverage to get thro ugh. Now that I'm retired, they might just tell me to go piss up a rope. d8

-)

I get started on this subject and off I go on a tangent. Yes, I realize it probably wouldn't help your situation. The point is that no, epoxy won' t bond to solder unless you take special steps.

There's nothing wrong with the tangential stuff - it might come in handy some day & it costs nothing to carry the knowledge around!

Am I understanding correctly? You think a smidge of thick vacuum grease on the embedded wires might block the water?? Thats an interesting idea.

Or maybe chain lube. Perhaps you could adapt pipe fittings to compress on one end of a wire sample, apply likely diluted or melted greases to the other and see if they block bubbling when pressurized.

-jsw

Ok, then I wonder whether epoxy will bond to the urethane enamel of solderable magnet wire instead, used in the same way.

I bought some UV sensors from this Australian company:

and they came with stranded gel-filled cable IIRC.

They seem to be a small company so maybe they will sell you some cable if the minimum order quantity is too large from usual suppliers.

I'm not sure I would take their advice on waterproofing though: one of the UV sensors went intermittent and then stopped working not long after it was installed outdoors.

nk I read that somewhere. But you can find epoxy that will adhere sold for glueing copper plumbing together.

bonding to surface oxide. Depending on the metal and the thickness and natu re of the oxide, this results in weak joints in stainless steel, aluminum, copper alloys, and, of course, anything containing lead. There are other pr oblem metals.

le it's coated with the mixed epoxy. This is sometimes called "scratch-in" preparation. I use it all the time, and it works great on stainless and alu minum.

I never tried it or looked into it, but I suspect it will be the same as f or other metals.

aluminum aircraft wing skins being a prime example. To work fast and to get more reliable results, industrial users have worked out various conversion coatings and etches for specific metals that need to be bonded with epoxy and other adhesives. On aluminum, for example,they use phosphoric acid anod izing, PAA, and I've heard there are newer, better conversion coatings for aluminum.

st call 3M or Loctite, or whomever, and ask to speak to an engineer. Or I d id. I was a trade magazine editor and I could use that leverage to get thro ugh. Now that I'm retired, they might just tell me to go piss up a rope. d8

-)

I wonder, too.

Urethances are formulated in so many different ways that I can't begin to g uess. FWIW, the conventional wisdom is that epoxy will bond to urethane (an d to polyester and methacrylate) better than any of them will bond to epoxy . Just watch out for the extreme elongation (ductility) of most polyurethan es, compared to the low elongation of epoxy. The difference can result in s hear failure right where they're bonded.

Thanks Charis, I'll have a look.