White lines syndrome on hardwood floors is the result of finish stretch and adhesion loss. The last five or ten years have seen the loss of certain solvents within finishes that gave the coatings better adhesion and elasticity. In this video I discuss the two types of scenarios that create white lines syndrome.
Adhesion loss across the seams of the boards in a floor will create the look of white lines. The problem exhibits itself particularly when a floor experiences minor cupping from excess seasonal moisture. Because finishes like oil modified polyurethane lay as a film across the floor, upward pressure from cupping pushes the finish off the floor at the raised edges. An additional culprit for adhesion loss is excess solvent trapped within finish coats applied quickly, in which the coating becomes more brittle.
Finish stretch is the other form of white lines syndrome that can happen. The finish that is most prone to stretching is isocyanate catalyzed waterborne finish. This type of urethane is very tough and unlike other film finish will stretch rather than break when seasonal gapping happens.
What you really need to know is where white lines can become an issue. The major issues of white lines syndrome in floors occur in wide plank floors, exotic flooring, and dark stained floors. If you are planning a project along these lines then you should be advised that this could become a problem. The only alternatives to avoid white lines are hardwax oils and conversion varnish such as Glitsa Gold Seal.