Legacy Industrial's HD357 is a concentrated concrete etch and cleaning product using an Organic Acid Salt as the primary ingredient. This product does NOT create the dangerous fumes that Muriatic or Hydrochloric Acid does, making it safer for your application. Coverage: 500-600 sq ft. per gallon for Delta-Dye Concrete Stain or Sealer/Coatings Prep. This product is best applied using a pump-up deck sprayer (all plastic). Follow all safety precautions listed on the bottle/container.