What grout is best for polished light colored porcelain stoneware on a warm floor (kitchen) to make the joints shiny? I know epoxy won't work because it's rough.
MULTIFILL SMALTO 1-8 is a colored polymer cement grout for filling interstitial joints, with a smooth and glossy texture. It has high mechanical strength, excellent color stability and excellent water resistance. Contains special antibacterial components, protecting the seams from the accumulation and growth of bacteria. Used for filling joints from 1 to 8 mm in width. Classified as type CG2 WA grout according to EN 13888.
Specify whether you want a glossy or smooth surface. If you want a smooth grout, choose Mapei kerscolorFF, but it also needs to be diluted with an acrylic additive.
For hallways and kitchen aprons, epoxy grout is highly desirable. It will make it much easier to clean in the future.
Actually the epoxy looks more glossy than any cement-based epoxy.