Roofing shingles are made in a continuous web process. Large rolls of glass mat are unwound and fed into the coater. At the coater, coating (asphalt with air blown through it) is applied to the top and bottom surfaces of the sheet. Mineral stabilizers are added to the coating which improve the shingle’s fire resistance and weatherability. Next, granules are applied to the top surface of coating. Granules are ceramically colored crushed rock; the granules give the shingle its color, but more importantly protect the coating from ultraviolet light. Backsurfacing is then applied to the sheet to prevent it from sticking to the machine and to other shingles when packaged. The release tape is also applied to the back of the sheet to prevent the sealant buttons from sticking to the next shingle in the package. The granules are then pressed into the topcoating. Once the sheet is cooled, sealant buttons are applied. The sealant buttons allow one shingle to bond to the overlying shingle on a roof, to prevent wind uplift. The roofing sheet is then measured and cut into shingles. At this stage, the two pieces of laminated shingles are adhered together. The shingles are wrapped into bundles and stored in the warehouse until they are ready to be shipped to the appropriate location.