Georgia asks…I’ve seen three types of nail strengtheners advertised: formaldehyde; protein; and, calcium floride. Is one of these better than the others? Which would be best for my nails, which are thin, weak, and break at the sides? The Left Brain responds: There are two basic kinds of strengtheners: Hardeners and Hydrators. By understanding the [...] Read more: whats-the-best-product-for-brittle-nails