http://www.iloveshelling.com/blog/2011/02/09/how-to-restore-color-to-your-seashells-tutorial/ Caution: Muriatic acid has controversy as to the damage it can do to shells (and humans if handled incorrectly). Please use with caution and read the blog post for more information. Tutorial on how to restore color to your seashells using muriatic acid solution to make them look bright, shiny and colorful! Mary from Sanibel Shell Crafters gave us some quick tips and hints to clean your shells then we had to try it. It works!