Does electric steam floor cleaners harm hardwood flooring?

Yes. Water can easily warp a wood floor. Electric steam cleaners say they are safe on sealed wood floors, but steam will penetrate in between the seams of the boards and in time causing damage that is not reversible.

The best products are alcohol based because they evaporate quickly.

Under no circumstances should a steam cleaning devise be used on a hardwood or laminate floor! Steam is essentially hot water. Water will damage your beautiful wood flooring. Consumers should contact their flooring manufacturer for safe cleaning methods and products.