I teach Lost Wax Casting in my High School Jewelry classes, and we have a high success rate. The one flaw we consistently have is “bubbles” which sometimes form in recessed areas of the casting. These are later removable with ball burs (in silver), but you can usually detect where that happened. Do you recommend a solution or treatment to the wax model before casting in order to prevent such “bubbles” from adhering? Thank you!