Surface staining is generally caused by spills which are not promptly removed, asphalt driveway sealer tracked in, the use of rubber or latex backed mats, etc.
Bottom-up staining can be caused by:
- Use of adhesives other than those recommended by Armstrong. Adhesive staining is generally dark yellow and appears in low embossed areas first. Generally occurs sooner in areas exposed to a great deal of sunlight.
- Failure to remove asphalt adhesive and/or other foreign materials from subfloor.
- Bacteriological staining which is usually a bright yellow (mustard color), bright pink, or gray-blue which eventually turns black. Just about every case of this type of staining occurs over on or below grade concrete which has been skim coated with gypsum-based patch. This type of staining can also occur in the presence of a water leak where the subfloor is constantly wet (around sinks, tubs, toilets).