Water is the enemy of wood floors, but it's especially harmful to laminate flooring. It isn't the finish that you have to worry about, but the fiberboard core. A spill that you manage to clean up quickly probably won't do much damage, but one that you leave on the floor can seep through the gaps between boards. The consequences can include:
From the Surface to the Core
Laminating is a general term that refers to gluing wood together in layers, but in the flooring industry, the word laminate has a more specific meaning. It refers to flooring with snap-together boards that consist of a fiberboard core and an artificial, plasticized surface. The top layer is extra durable -- even more durable than that of many hardwood flooring boards -- but the core can absorb moisture like a sponge. Manufacturers treat the core with waterproofing sealer, but that seldom prevents seepage once water gets between the flooring and subfloor. Damaging water can come from above or -- if the floor is on a concrete pad -- from below.
If you spill liquid on your laminate floor, the first order of business is to dab it up with a sponge or absorbent cloth. Avoid wiping, especially if the liquid is near a joint, or you may force the liquid between the boards, and it may swell the tongue or groove. For this reason, you should never clean the floor with a steam mop or even a wet one -- only damp or dry mops are suitable.
Once you notice the signs of water damage, there is little to do about it other than replace the affected boards. Laminate flooring isn't hardwood -- you can't sand it or level curls and raised edges by scraping them down. The good news is that board replacement is a job that you can probably do yourself, either by disassembling the floor back to the damaged area or cutting the boards out and gluing in new ones.