Black specks are a form of injection molding machine contamination, produced by carbon build-up. Black specks can be a nuisance for companies processing thermo-sensitive resins. It is important to remove the carbon before too many layers of degraded material form on the screw. After a certain point of carbon build up the only way to truly clean the screw is to pull it and manually clean it. Ultra Purge purging compound is designed for purging black specks from multiple types of machinery, across several different applications.