My nails have never looked better since I stayed using this last year. The whites are white and my nails are strong. I'd only use it if you have thin weak nails. At first I used it 3x per week and I'm down to once or twice per week. Be careful not to get this on your skin. Best litmus test for me: I'm prone to somehow bending my nails backward (ouch). Since using this product, not only do they not break, they just snap right back in place. I love this hardener!