[marozie]

I looked up "allergy to epoxy resin" and found this article on DermNet NZ (NZ as in New Zealand):

Allergy to epoxy resin
Epoxy resin is a chemical that is part of an epoxy resin system. Epoxy resin systems are used widely in industry because of their strong adhesive properties, chemical resistance and toughness. Common two-part epoxy resin systems contain epoxy resin, catalysts/curing agents, and diluents and/or other additives. Any of these chemicals on their own may cause irritant and/or allergic contact reactions. Cured epoxy resin (the fully hardened combination of the epoxy resin system chemicals) should be non-irritating and non-sensitising.

What are the reactions to epoxy resin allergy?
Typical allergic contact dermatitis reactions may occur in individuals allergic to epoxy resin or other components of an epoxy resin system. The uncured epoxy resin, hardener and diluent are powerful irritants and potent sensitisers. Skin contact with the hardening agent may cause severe burns. They can also cause a severe allergic contact dermatitis characterized by redness, swelling and itching. Skin should be washed with soap and water if any contact occurs. In addition, hardeners and diluents are more volatile than resin and may cause allergic reactions from breathing in fumes. Cured epoxy resins are seldom a problem but it has been found that measurable amounts of uncured reagents may remain in the "cured" resin after 1 week.

So, as I guessed, the cured form of the epoxy shouldn't be hazardous, but the last sentence explains why I developed contact dermatitis.

 

[pdupiano]

I'd second the nail polish idea or perhaps you can check on something called liquid skin. Liquid skin is supposed to be a liquid bandage and I know some even come in the form of a spray can, so it might be easier to plug up the sound holes and just apply a coat or two on the iems. Good luck and I hope the irritation goes away.

 

[SilverCans]

what do UE, JH, and hearing-aid companies use? whatever it is should be obtainable, no?

 

[SuryA]

Thats just cyanolite (superglue), I don't think you can get a smooth coating with that and it will probably chip quite fast.
I'd say the irritation probably comes from the acrylic rather than the epoxy though..

 

[marozie]

Quote:

Originally Posted by SilverCans /img/forum/go_quote.gif what do UE, JH, and hearing-aid companies use? whatever it is should be obtainable, no?

Well, again, the bases that they use are no different that what we have access to, like acrylic and urethane, as far as I've been able to gather. It's the solvents that are hazardous and they might have access to formulations that have fewer irritants, or just go through additional steps to remove them before they send the IEMs out. Professional manufacturers I'm sure cure the product in a vacuum chamber, which in addition to preventing bubbles in the final product would also suck out the solvents speeding up this process.

Quote:

Originally Posted by SuryA /img/forum/go_quote.gif I'd say the irritation probably comes from the acrylic rather than the epoxy though..

So, I never mentioned this, but the acrylic (Krylon) was taking way too long to dry in between coats and I was having to put on a ridiculous number of coats to achieve a smooth finish, so I ended up just grinding it off, preparing some more epoxy in a little pool, and dunking the IEMs in it. This left a perfectly smooth finish, but I started using them right after it cured, and apparently even though there's a 90 minute "de-casting" time it says on the container that it takes 2-3 days for the compound to fully cure. Again citing the "uncured reagents may remain in the 'cured' resin after 1 week" statement.

 

[SuryA]

Then maybe in a couple of days it'll be just fine!

 

[SilverCans]

Anyone give Star Micronics BAs a good listen?

 

[piotrus-g]

Quote:

Originally Posted by SilverCans /img/forum/go_quote.gif Anyone give Star Micronics BAs a good listen?

Have you listened to ER6i? I have. Very detailed but flat sound in terms of soundstage and response. Lack of bass and definition.
I have like 10 different Star Micronics drivers (incuding ER6i-like-drivers but I cant give them a listen. I'd have to make a shell for this purpose. It would take great amount of time and money.

 

[SilverCans]

piotrus-g you might be able to get away doing what the orignal poster of this thread did, wire them up and place them in a foam tip to give them a quick eval. What do you think? Never heard er6i btw.

 

[marozie]

Quote:

Originally Posted by MaoDi /img/forum/go_quote.gif Can someone figure out how to make shells from Polycarbonate...

Why polycarbonate? It seems like it's mostly used for extrusion molded stuff, soda bottles, etc.

 

[FYJX]

Quote:

Originally Posted by marozie /img/forum/go_quote.gif Why polycarbonate? It seems like it's mostly used for extrusion molded stuff, soda bottles, etc.

Because it's one of the strongest polymers out there. Why not use it?

 

[marozie]

Quote:

Originally Posted by MaoDi /img/forum/go_quote.gif Because it's one of the strongest polymers out there. Why not use it?

Well, the only reason would be that since it's usually used in extrusion molding I would assume that requires getting it really hot so that it's in a "molten" state. Ah, I'm looking on Wikipedia: "Polycarbonate has a glass transition temperature of about 150 °C (302 °F), so it softens gradually above this point and flows above about 300 °C (572 °F). Injection moulding is more difficult than other common thermoplastics owing to its non-Newtonian fluid flow behaviour."

So, you have to get it really, really hot for it to be "liquid." I don't know how practical that would be, not to mention that it could damage any number of the electrical components, or the mold itself depending on what it's made out of. Plus, why do you need indestructable IEMs, just in case you run them over with your car?

 

[FYJX]

Well yes! you never know!

 

[DCinLBV]

I found a clear acrylic nail polish gave a safe, glossy final coat without any polishing or buffing, but apply it lightly and give it at least a day to fully harden. I also let my epoxy cure for 5 days before applying it.

If you want hollow shells, you can use an old-school method of tumbling. Just prep your molds with some scrap tubing and wire bent into the shape of your sound ports. Lightly coat them in vasoline, or mold release. Put 20-30 ml of slow (at least 1 hour to set) curing resin in the molds and use painters tape, or something, to seal the backs of the mold. Double seal the mold in ziploc bags. Insert everything in a foam package (a small pillow works great) and place in a dryer. Run it without heat for a hour. Then you just have to carefully cut open the backing to insert everything.

 

[marozie]

Quote:

Originally Posted by DCinLBV /img/forum/go_quote.gif I found a clear acrylic nail polish gave a safe, glossy final coat without any polishing or buffing, but apply it lightly and give it at least a day to fully harden. I also let my epoxy cure for 5 days before applying it.

I just picked up some clear acrylic nail polish last night. You're a more patient man than I -- waiting 5 days?! But now I'm paying the price for my impatience: itchy ears pretty much blows. It's almost subsided, but still there. I imagine this will be followed by some skin sloughing at some point, which should be pretty fun.

Quote:

Originally Posted by DCinLBV /img/forum/go_quote.gif If you want hollow shells, you can use an old-school method of tumbling. Just prep your molds with some scrap tubing and wire bent into the shape of your sound ports. Lightly coat them in vasoline, or mold release. Put 20-30 ml of slow (at least 1 hour to set) curing resin in the molds and use painters tape, or something, to seal the backs of the mold. Double seal the mold in ziploc bags. Insert everything in a foam package (a small pillow works great) and place in a dryer. Run it without heat for a hour. Then you just have to carefully cut open the backing to insert everything.

That's brilliant! How do you like the sound of your TWFK - ED setup by the way? What are your impressions?