It shouldn't be necessary to seal your laminate floor. The flooring boards come with a super-hard finish that is designed to last for the life of the floor, and the boards are designed to lock together so tightly that water can't seep between them. It's difficult to seal the gaps between boards any better than they already are anyway, and an extra surface coat won't do much good -- and could even be harmful. Sealing the perimeter of the floor to prevent water from seeping under the floorboards, on the other hand, is a recommended practice.
Not Good for the Surface ...
It's natural to suppose that adding a seal coat to a laminate floor gives it extra protection, but a consideration of the nature of the existing finish should convince you otherwise. Most laminate flooring products aren't wood -- a typical board consists of a fiberboard core covered by a layer of melamine resins and aluminum oxide that have been stamped to look like wood. The surface layer is essentially plastic, so there's nothing to seal, and flooring professionals recommend against it. Because it can't penetrate, the seal coat will likely peel off and it often makes the floor more slippery and dangerous.
... Or for the Core
You may want to apply a waterproofing sealer in the hope that it will seep into the gaps between boards and protect the fiberboard core. The danger with this approach is that the sealer might soak in, just as you were hoping, and in the process swell the fiberboard and produce the curling and lifting at the edges that you were trying to avoid. Even if this doesn't happen, allowing anything to soak into the seams is a risky, last-resort strategy. Most manufacturers seal the locking tongues and grooves with wax anyway, so the addition of waterproofing sealant is redundant. If you really want to apply extra sealant to the locking mechanisms, the time to do it is when you're installing the floor.
My Floor Shows Moisture Damage
If the purpose of applying the sealer is to stave off further moisture damage, such as finish discoloration or warping floor boards, it's a bit like applying a Band-Aid to a broken bone. The moisture damage is being caused by high humidity in the room, seepage through the subfloor or improper cleaning practices.
- The floor should have been installed with an approved moisture barrier on a dry subfloor. If the moisture barrier is missing, or the subfloor is wet, and the floor shows moisture damage, there's no real alternative to removing the floor, letting the subfloor dry out and reinstalling it the right way.
- The floor may be installed in an unsuitable location, such as a basement or mudroom, where moisture is an overarching factor. Replacing the flooring with a product more appropriate for the conditions is probably best.
- You may be in the habit of wet-mopping the floor. As far as laminate flooring is concerned, that's a recipe for disaster; you should never allow water to stand on it. Applying an extra seal coat doesn't change this fact.
Sealing the Edges
Applying a coat of 100 percent silicone caulk to the bottom edges of the baseboards is recommended, especially in bathrooms, kitchens and other rooms in which water is present. You should also seal around cabinets, plumbing fixtures -- such as toilets and pedestal sinks -- and doorjambs; in short, anyplace where water can seep under the floor and infiltrate the undersides of the boards.