I have done these before using a 3% mix but i still had to scrub some areas, is it some thing i did wrong?.. I heard that it would be difficult for our method to clean soot/exhaust/hydrocarbon staining....anyone here familiar with these type of jobs? advice would be greatly appreciated to improve me efficiency.

Thanks. 

Hi Laurie

Glad you have just posted this, as I have just quoted a gas station, and did not realize that these can be alot harder to clean....hope I haven't under quoted . Suppose all in the learning curve!!

Has anyone else seen this post to give some helping info? Please help