Sea Buff is an excellent product for use on all new masks, or masks that have been in use or storage for a while. The manufacturing process leaves new masks with a silicone film on the inside of the lens. Masks that have been in use or storage for a while may also generate a build-up of film from other materials. Masks with this film build-up will usually have issues with fogging... even if mask defog is applied. Sea Buff is a safe mild abrasive that will remove film build-up and prime the lens surface so that mask defog, such as Sea Gold, will be completely effective.