My 2 cents on this old thread:
My 'm' fingernail splits as soon as it's beyond the nail-bed. This is due, I believe, to a deep cut I suffered years back on the distal phalanx, between the knuckle and cuticle. So I need something artificial on 'm', for sure.
I've had good results from visiting salons, once with built up acrylics (back in my chicken-picken tele-playing days); probably not a good sound for classical; and more recently with silk-wraps for classical playing.
I've had quite good results doing the following simple silk wrap technique at home, modified from the salon processes.
1. Scratch up the nail with a sanding board - no need to file too hard; you don't want to lose thickness.
2. Clean nail with isopropyl alcohol - acetone works well too but is stronger than needed and leaves the nail white, "dusty"?
3. Put a coat of thick superglue on nail - seems to me hardware store thick/gel super glue and made-for-nails cyano-acrylate brush-on glue are equivalent.
4. Dry. - The salon used a little fan, I wave my finger around til dry.
5. Put on silk wrap (about 2/3s of nail) - The salon covers the full nail, but leaving some nail uncovered seems healthier, if not so fancy
6. Wet silk with thin super glue, tapping down with tip of tube for coverage and contact. Don't use too much glue.
8. Repeat 5,6,7 one or two times, for 2 or 3 silk layers.
I can count on the wrap staying in place at least 2-3 weeks. I've never had a fungus or thinned the nail so bad that I can't easily replace the worn or loose silk wrap. (My wife told me not to leave a separated wrap in place for long, as that will invite fungus.)
While the wrap works well, I have found that the silk does sort of fray on the nail tip after multiple filings. Also if the nail takes a hit, it can crack - it'll continue work OK for a while, but the wrap will be prematurely doomed. Adding a bit of thin superglue to the edge and to any cracks seems to mitigate these problems.
It's tough to get a strong, clean edge on this split nail with the wrap. If the real nail contacts the string, it's got that gap, so it's not got a smooth edge. If the silk overlaps the real nail and contacts the string, then the fraying is worse.
Anyway, I've got IBD Gel Builder and a UV lamp on its way from Amazon. Seems some of you went the other way, from gel/UV to silk wraps. We'll see. (Wow, talk about First World problems