The White Line Syndrome

The Problem

Recently there has been more discussion of white lines showing up over dark-stained floors. This is not a new problem for floor finishes, but it is becoming a more common one. As VOC regulations become more stringent around the country, more floor finishers are trying out waterborne coatings. They are also finding that there are more differences in the products

than just smell and application techniques. When a floor is stained with a darker-colored stain and then finished with waterborne coatings, white lines between flooring boards may appear anytime, especially during seasonal changes when the humidity drops in our homes.

 

 

 

The Reason

The reason for the white lines is that waterborne and other coatings tend to stretch, some more apparent than others. Research shows that the isocyanate crosslinked products we tested stretched across board edges, leaving white lines.