Q.: What chemicals in ready-mixed concrete will cause vinyl flooring to develop yellow spots after the flooring has been in place for several months? I've had this happen several times in residential applications and want to understand the cause so I can prevent it from happening again.

A.: Published information indicates several possible causes of yellow spots. In many cases, overall or spotty yellow staining is related to the adhesive used to install the vinyl. An improper adhesive changes color beneath the floor and migrates through the back of the vinyl. The literature also refers to discoloration caused by alkalies in underlying concrete but describes this discoloration as a bleaching, not a yellowing.

In either of these cases, the cause of the staining lies under the vinyl. The literature says stain location can provide clues to the stain's origin. Overall stains that are darker in embossed areas of the vinyl are good indications that the staining is coming from under the vinyl flooring. Stains appearing on the unembossed areas are probably caused by tracking or spillage on the vinyl surface.

Tracking or spilling asphalt driveway sealer or paint onto a vinyl floor also causes yellow spotting. These spots, which usually are permanent, are typically heaviest at room entrances and are most apparent on white floors.

Finally, the yellow spots might be due to a manufacturing defect in the sheet vinyl wear layer. One such defect is plasticizer drops, which are generally random bright-yellow or dark-brown spots, the size of a half-dollar or smaller.


Resilient Floor Covering Inspection Manual, Chapter 7, Academy of Textiles and Flooring, Whittier, Calif.