After years of using false nails I have finally been able to get acceptable nails. I tried a lot of things but what worked for me is the Mavala nail hardener along with a treatment I made by myself with jojoba oil and horsetail dry leaves. Beware, Mavala contains formaldehyde, but it is what makes it work (formaldehyde crosslinks proteins, so it crosslinks the nail keratin). My nails quickly became harder, but very brittle, so technically not better at all. The jojoba/horsetail mixture did a fantastic team job with the formaldehyde, now my nails are stronger and no more brittle, they don't break anymore and don't wear out when I play.
For the jojoba/horsetail mixture I put crushed horsetail dry leaves and jojoba oil in a glass vial and soak the vial in water at about 180°F for 1 or 2h. I hydrate my nails daily with a drop of the oil
Benoît Raby, Engelmann sp/Ziricote
11-strings alto guitar by Heikki Rousu, sp/indonesian RW