A certain amount of abrasion and scratching from foot traffic, children playing, pets, stationary objects and carts or dollies, cannot be avoided and will eventually erode the existing floor finish on a decorative concrete floor. This floor finish - or "polish" - needs to be restored periodically so that the concrete sealer and stain below is not affected. How often to re-coat with floor finish depends most on the building environment. In homes, once per year is a good rule of thumb, whereas with businesses, it should be more often: at least once every 4 to 6 months.
Always use a commercial grade floor finish from a janitorial supply house (local or online) and not one from a hardware or grocery store. Apply the finish sparingly, with a garden sprinkling can, then spread with a lambswool applicator or loop end mop in very thin, uniform coats. (Note: loop end mops used for applying finish are slightly different than those used for damp mopping: they are made of a finer fiber such as nylon filament yarn or microfiber.) A new coat of floor finish should not take long to apply and will dry in 30-45 minutes, if not applied too heavily. Also, if the acid-stained or decorative concrete floor has a scored or saw-cut pattern, be careful not to fill those joints with floor finish. Floor finish goes down milky white and may collect too deep in the cuts to clear up as it dries.
Floor finishes are inexpensive - usually no more than $20 per gallon from a janitorial supply house. They come in matte, satin, or high gloss, and vary in optical clarity and depth, as well.
Also, "Hazing" is a common problem encountered with floor finishes. It's caused by: 1) excessive humidity during application; 2) applying additional coats before previous coats have fully dried; or 3) applying over a dirty or contaminated surface. "Powdering", or chalking, of a floor finish is caused by: 1) applying under cold conditions (below room temperature or near poorly insulated exterior walls or entrances); or 2) applying over an unsealed or excessively porous substrate. These problems can be resolved by stripping the floor finish, correcting the source of the problem, and then re-applying more finish.