Paint plugs and masks are used to cover areas of part that need to be protected from getting painted or coated. These plugs and masks are often used many times until the coating build-up becomes too much to be effective as a protectant.
It can be expensive to replace plugs at this point as they are often custom shapes and designs made specifically for a particular part. While chemical strippers can be used, this poses the problem of chemical disposal (often of a hazardous solvent). Abrasive blasting is also an option, but this only works best on hard surfaces rather than softer, rubbery parts.
Vibratory tumbling works very well to remove the paint and produce a clean-as-new plug. The process can take some time depending on how many coats of paint are on the plug. It is a single-step process using an abrasive Ceramic Media and a solution of the Kramco 1010 General Purpose Liquid Compound. After just a few hours, the parts can go from the coated ring shown to a ready-to-use plug!