Solving a Mysterious Porcelain Tile Problem

The Italian-made 12-by-18-inch tiles were just what the homeowner wanted. White with light streaks of gray, they complemented the white base cabinets and grey quartz countertop and contrasted with the dark wood uppers and tall cabinets. The homeowner chose porcelain for its durability and stain resistance, but he wanted a matte finish to avoid any glare and reflections. With the tile laid and awaiting grout, the floor looked exactly as he had imagined it, even in shallow-angle light from the surrounding windows.

But the day after grouting, the floor looked entirely different. The crisp uniformity of the matte surface now appeared splotchy, with slight but noticeable shiny spots here and there on each tile. The tile sub said it was just grout haze, but after applying a mild acid cleaner, the problem seemed worse. A second and third cleaning did nothing to improve it.

The homeowner was referred to design-build remodeler Alex Dean of The Alexander Group, in Bethesda, Md., who visited the site and agreed that the surface of the tiles on the floor was splotchy compared with unused tiles in the box. He wasn’t sure about the cause, but agreed to take a sample to his long-time tile vendor, Jason Brunetti. Brunetti is branch manager at Mosaic Tile Co., in Rockville, Md., and porcelain tile is something of a specialty for him. He looked at the unused sample tile Dean showed him and offered a clue as to what might be going on.

I followed up with a phone call to Brunetti, who explained that at the factory, large porcelain tiles are boxed flat, face up, with the top surface of one tile facing the back side of the tile above, which has a rougher texture. “So you have to provide a spacer between tiles, but it’s difficult to incorporate paper or some other material into the assembly-line process,” Brunetti said. Instead, a short, thin strip of wax is applied at several spots on the finish surface (photo, below) to act as a spacer. Dean told me that Brunetti had demonstrated this by taking a razor scraper and peeling a thin ribbon of wax from the surface of the sample tile.

“The wax usually gets rubbed off when the grout is polished,” Brunetti told me, and although he said he couldn’t be sure without actually inspecting the floor, he agreed it was possible that instead of being removed, some of the wax was embedded in the small irregularities of the matte surface.

Brunetti’s recommendation for this floor was to clean the surface with NanoScrub, which he had also demonstrated for Dean by scrubbing the wax off the sample tile. “It’s a cream with a little bit of grit in it,” Brunetti said. “That and a scrub pad will eat away at the wax.” While a power scrubber isn’t necessary for spot cleaning, Brunetti said that it will do the job for a large area.

Mystery solved.