100 grit, on NATURAL nail!? I couldn't have read that right. 240!! 240!!!!! I still hear people say 180 around sometimes but even that's considered outdated and way too low now.
Heck my natural nails are super buffed to high gloss shine and I still don't take a 240 to them for gels or gel polish I just do amazing prep for everything else...
Cuticles, cleanse, dehydrate,
NO bonder. And my gels stay on perfectly. Then when I remove them, my nails are still mirror smooth underneath.
No 100 grit file!!! You will destroy people's nails.