I wouldn't bother. I use silver solder for special occasions (Felder stuff) but it's too expensive to use all the time. You're probably fine with 60/40 loctite multicore. Just keep your parts, iron and boards clean and it's no harder.
Decent soldering station + correct and well taken care of soldering tip + thin multicore 60/40 + tools and supplies to clean your board + a bit of soldering training. There is lots of really good instructional videos on YouTube which is how I learned to solder.
It really depends on what you are building. If you're building a HAM transmitter then it is very useful.
The main use cases are certain alloy joints. I’ve seen it quoted as having better mechanical strength but that’s not what’s solder is for!
That depends. Back in the day when I did this work large end stages were built pretty much 'in the air' and in the stuff I worked on there were trimmers and coils that were pretty heavy and that were only supported by the solder. So we used silver for those joints, and they held up pretty good.
Hefty => 1KW and up...
As for the skin effect, that is the reason we did it in the first place, but I never had access to the kind of gear that would have allowed me to test in practice what the difference was and I've long ago stopped doing this sort of thing.
Skin effect makes sense. Hence why I use silver plated stuff in my VHF stuff.
Where do you buy this stuff? I’ve looked everywhere and I can’t find it. Amazon doesn’t have it, Mouser doesn’t have it, Digikey doesn’t have it. Seems like it might be discontinued!
https://www.digikey.com/en/products/detail/kester-solder/24-...
https://www.newark.com/w/c/tools-production-supplies/solderi...
Also, Amazon appears to have it, per this listing:
https://www.amazon.com/MULTICORE-LOCTITE-3096525-M-SOLDER-WI...
Looks like you can get it from Digikey as well:
https://www.digikey.com/en/products/detail/multicore/386824/...
Note that part of the problem might be if you're searching for "Loctite Multicore" and not just "Multicore". I think the brand might have been sold off, or something of that ilk, so you may not see it with the "Loctite" branding everywhere. I don't know the backstory on that entirely, but it's something I've noticed (being a big fan of Multicore solder!)
And since this whole sub-thread started with a mention of "silver bearing" solder IIRC, I'll point out that there are a couple of decent options there. I actually like the Radio Shack brand silver-bearing solder, but I don't know if it's still available or not. But Chip Quik have a product in that space[2] and they are a pretty reputable brand so I would expect it to be fine. That said, I don't think the whole "silver bearing" thing is terribly important and I rarely use the stuff myself these days. YMMV.
[1]: https://www.aliexpress.com/i/2251832830340296.html?gatewayAd...
[2]: https://www.amazon.com/Solder-Wire-Lead-Silver-no-clean/dp/B...