Grout is porous. That's the whole reason DIY tile cleaning never lasts more than a few weeks — your mop is depositing dirty water directly into the grout lines, which then dries and locks the contamination in.
Professional tile and grout cleaning uses rotary high-pressure extraction, typically 1,200+ PSI, with simultaneous suction. Hot alkaline pre-treatment dwells on the buildup first, then the rotary tool flushes grout lines from the inside out, and the suction pulls everything up before it can re-deposit.
For most kitchens and bathrooms, this restores grout to within 1–2 shades of original. After cleaning, Spiker applies a real penetrating sealer that protects the grout from re-soiling. The sealer is clear — it does not change the color of the grout. We do not color seal.
Why no color sealing? Color sealing is a short-term cosmetic fix that fails within a year and locks the customer into permanent annual repair cycles. It's a hack used to dress up a home for sale. Spiker leaves you with a real clean and a real penetrating sealer that holds up for years, not months.