I know there is a mayo thread on here and I actually posted this on it; however it is multiple pages long so I thought I'd make it easy to find. On rare occasions when making homemade mayo it will fail and separate into an unusable mess. Rather than throw it out and start over and waste everything, fix it. Add an egg yolk, start beating it and slowly drizzle in some more oil. Mine fixed like magic. Also if you've ever wondered about doubling the recipe, I tripled it yesterday and it did great.