Grout joints 1/8″ or smaller are typically recommended for glossy wall tile, polished stone, glass tile, delicate glass tile and mixed material mosaics. Choosing a narrow grout joint on a floor with rectified-edge porcelain can help to achieve a more monolithic appearance. When grouting joints 1/8″ or smaller, typically an unsanded grout such as MAPEI Keracolor U is recommended. However, MAPEI Flexcolor CQ grout uses a special type of coated sand and MAPEI Ultracolor Plus FA grout uses a unique fine aggregate. Therefore, MAPEI Flexcolor CQ and Ultracolor Plus FA grouts can be used in joints as small as 1/16″ wide and with most installations where an unsanded grout is recommended. Still, a test is always recommended to confirm compatibility.