When cleaning day comes, engineered wood flooring is no different from solid hardwood. Your engineered flooring may have come prefinished from the factory, or it may have been installed as unfinished boards that were finished on site. Either way, the optimal cleaning method depends on the finish. It's always best to use products recommended by the flooring manufacturer or installer/finisher when cleaning prefinished flooring, but a few guidelines apply to all types of hardwood flooring, whether engineered or solid, prefinished or finished on site.
General Cleaning Guidelines
Flooring manufacturers are unanimous in recommending frequent sweeping or vacuuming. If you vacuum, use a soft attachment and avoid beater bars, which can scratch even the hardest finishes. Occasionally mopping the floor can remove the dull, grimy film that inevitable collects over time. The safest cleaning solution is pure water, but it doesn't hurt to add an ounce of dish soap per gallon of warm water to help emulsify grime and make it easier to remove. Mop with a micro-fiber or sponge mop, and wring thoroughly to avoid leaving water standing on the floor, which can turn the finish milky. Rinse with clean water, and dry the floor immediately after mopping to remove any remaining moisture. Note: Do not use soap that contains any oils or waxes of any kind.
Bringing Back the Shine
No matter how thoroughly you clean your floor, foot traffic is bound to wear the finish, and it will turn dull. As long as the finish is still in good shape -- which means it isn't cracking or approaching complete wear-through -- you can bring back the shine temporarily with a spray-and-buff procedure. Consult the floor manufacturer for recommended products.
Using a simple wood floor cleaner/restorer is straightforward -- spray it on the floor and allow it to fill microscopic scratches and dents, then buff it with a lambswool floor buffer when it dries. Note: Many wood flooring products leave an oily or waxy film that makes it impossible to screen and recoat a floor in the future; be sure to check with the flooring manufacturer; don't trust the claims on the cleaning/restoration product.
Restoring the Finish
If the surface on an engineered wood floor is too far gone to bring back with an enhancing product, you can still restore shine without refinishing. The procedure is called screening and recoating, and it's typically used on hardwood and engineered floors that have been finished on site. The process involves scuffing up the finish with a floor buffer and 120-grit sanding screen, then applying one or two coats of fresh polyurethane or similar finish as if you were finishing the floor for the first time. This procedure can extend the life of the finish for several years.
Screening and recoating is best left to professionals; it requires expertise to know whether a floor can be recoated and what type of finish to use, not to mention the often tricky application of the finish. Prefinished floors can be difficult to recoat. Again, consult the flooring manufacturer for recommendations. Recoating may void a prefinished floor's warranty.
Things to Avoid
In general, avoid high-pH cleaners, such as ammonia; they are caustic and cause microscopic pitting that dulls the finish. You should also avoid acidic cleaners, such as vinegar. Never clean the floor with oil soap or any cleaners containing wax -- both can leave dull deposits that can be difficult to remove and will prevent a bond with a recoating finish, if you ever need one. Waxing isn't recommended because of the propensity of wax for dulling and yellowing. Wax also eliminates the option of recoating, as do many floor polishes.