Content of crystalline silica phases in porcelain stoneware

Kitchen and bathroom countertop is a demanding application, where high aesthetic standards must combine with durability, ease of maintenance, and resistance to heat, stain, scratch and chipping. The hard materials and composites used for high-end countertops usually contain crystalline silica phases that can be inhaled by workers during drilling and cutting operations. The occurrence of silicosis and other respiratory diseases in machining workers makes it important to know exactly how much crystalline silica is present in countertop materials. This paper collects over 300 quantitative determinations of quartz and cristobalite in porcelain stoneware products and compare these contents with other countertop materials. The sum of crystalline silica phases in porcelain stoneware is on average 21 ± 5 % by weight (mostly quartz). This content is lower than granite (∼30 %) and much lower than engineered stone (∼90 %). Possible ways to reduce the amount of crystalline silica phases in ceramic slabs are overviewed and critically discussed.