Castor oil is a penetrating oil and also a fungicide. I always wondered what the old machinists meant by a penetrating oil. When i first applied Castor oil, the first effect was that the thickened popcorned nails shrunk back to normal thickness. This had never happened before with anything else. I kept at it. It took a while, but what i learned to do finally was to apply a thick layer and allow it to actually penetrate. This takes a full twenty minutes and it will be absorbed. Doing this after a few days of repetition the cuticle separated leaving a fresh skin contact zone. Again, take your time with this and be generous with the oil. No one can guaratee a result, but I do think that my nails will finish off clean. They appear clear right now while I wait for the nail to carry off damaged nail portions. If not, I can simply do a do over anytime it shows up. This is definately superior to having an infected nail. My take home is that it impacts immediately and