The process of removing some stains may require the use of highly acidic products. These stains may include rust, coffee, tea, red juice stains and many others. It is important to neutralize this acidic pH and return carpets to a near neutral pH. This protects the carpet from long term attack by the acids and guards against individuals coming into contact with treated carpeting and developing a reaction to cleaning materials left in the carpeting. Residue-free – Rinses completely. Works fast – Neutralizes excess acid.