Covering silver wire for use as a speaker cable

If it's "very fine", I assume you mean very 'thin', as oposed to very 'pure', so just how are you going to layer and bundle it to make large enough conductors for speaker cable? And will you be using a two or four conductor configuration? And how will you twist it uniformly?

And that's all before you figure out how to jacket/insulate it so it is protected from air and tarnishing. If you can do all that, you won't have to worry about shorting ;-)

Ozzy, so, you were referring to the quality of the wire (although 26 AWG isn't exactly heavy;-) The problem with silver is it tarnishes rapidly when exposed to air; and if you want to bundle/twist several together strands together, they need to make good contact, which they won't if they begin to tarnish. So it's essential to either coat each strand with some kind of high temperature polymer ike Paul Speltz's Anti-Cable (not generally a DIY operation) or enclose the wire(s) in an airtight jacket of some kind.

I think you could probably do the latter using 4 foot lengths of shrink tubing (clear would be nice ;-) and then covering the joints with another short length of shrink tubing. An inexpensive heat gun makes shrinking the tubing pretty easy. I'd also recommend you make the cable in two separate runs for each speaker. That way you virtually eliminate the capacitance and inductance problems of 2 conductor single jacket cable.

Shink tubing is available at electronic parts stores (B+M or online.) It comes standard in 4 foot (or maybe it's 5 foot) lengths. I suggested it because you can get it large enough (in diameter) to easily snake the wire through, and then it will heat shrink to 50% of its original diameter.

It is made of polyolefin which I have to assume has great dielectric properties since it's used to insulate wire ;-)
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Oz -- ERS cloth can be a problem if you use too much of it. If you want to play around with some let me know. I have a small, but dwindling stash of ERS (and some 50%Stillpoints too ;-)

My favorite solution for temporarily keeping bare wire away from other things and each other, is to thread the runs through foam swimming pool noodles. (Very festive!)

They also make great cable lifters cut into 6" lengths and threaded onto the speaker cable. (Yes, they can be spray painted ;-)

Ozzy, don't bother with the pipe foam; been there! It's a nicer color granted, but the split down one side makes it difficult to work with in this application.