OK. I didn't see a VCT catagory so it gets thrown in with vinyl. While working at a school, I was shown this by the janitor. The tile is around 6 years old. He strips and finishes it yearly and the bumps are there after stripping also. I scraped some of the bumps and it appears to be tile material. It's kinda randomly scattered throughout the halls. What would be the culprit here? I was thinking that someone may have gotten something on it before one of his earlier finishes.