 Does your composite deck look like this? It could look like this. Cortoclean has been developed specifically for use on all composite decks, docks and fences. It will remove stains caused by mold and mildew, grease, oil, rust, barbecue stains, spots like these, and so much more. Cortoclean is recommended by leading composite manufacturers and is environmentally responsible. Each bag of Cortoclean will clean approximately 300-500 square feet, 300 square feet at maximum strength, 500 square feet for routine cleaning at minimum strength. Remove all items from the surface that you do not intend to clean or damage. This includes all patio furniture, plants, barbecue or any other items that are not intended to be cleaned. If you have items below your decking surface, you should protect or remove them. You should always water plants, shrubs and grass before cleaning with Cortoclean. Doing so will help protect them. For best results, we suggest using a pump sprayer, hose, bucket, brush, and mixing stick. You should remove all debris between boards and brush away prior to cleaning with Cortoclean. If the railing system is not made of composite, protect it. Do not get Cortoclean on items that are not composite. Here we are using pre-taped painters plastic to protect this glass railing. When cleaning with Cortoclean, we do not suggest cleaning more than 10 square feet at a time. You don't want to get ahead of yourself. If it is your first time using Cortoclean, clean a couple of deck boards until you get the hang of it. When mixing Cortoclean, you should use a maximum of 5 scoops of Cortoclean to 1 gallon of water. This may be necessary to remove mold staining or other difficult to remove stains. For routine cleaning, use up to 2.5 scoops to 1 gallon of water. The first time you use a pump sprayer, you should use a small amount of water. Thirdly mix all Cortoclean powder crystals until they are dissolved. Once the crystals have been dissolved, pour into pump sprayer. Application and coverage is best when using a pump sprayer. Once the mix solution has been poured into the sprayer, you will then pump the sprayer creating pressure. If you have a railing system that is made from composite, you should clean it from the top moving down. Always start at the highest point on railings and second story decks, working your way down. Notice how Cortoclean works by showing signs of action. Also note that when composites are wet, stains are magnified. If stains are still present, allow composite to thoroughly dry and repeat application. You do not want any stains to be visible when you are done cleaning. Apply Cortoclean to a dry surface in direct sunlight between 65 to 85 degrees Fahrenheit for best results. Allow the product to work on the composite for up to 20 minutes or until Cortoclean becomes dirty. If the Cortoclean begins to dry from the composite, mist the area with additional Cortoclean and or work smaller areas. If you find it scrubbing with the brush helps, you can do so. Let the Cortoclean work for 5 minutes after spraying, then scrub. When your composite is clean, rinse with water. Here is a before photo and an after photo. Cortoclean really made a difference on this deck. Again, apply Cortoclean to a dry surface in direct sunlight in temperatures between 65 to 85 degrees Fahrenheit for best results. Allow the product to work on the composite for up to 20 minutes or until the Cortoclean becomes dirty. If the Cortoclean begins to dry from the composite, mist the area with additional Cortoclean and or work smaller areas. If you find it scrubbing with the brush helps, you can do so. Let the Cortoclean work for 5 minutes after spraying, then scrub. When your composite is clean, rinse with water. Here is a before photo and an after photo of how Cortoclean made a significant difference on this deck. This is what we're looking for. Don't just sort a clean, Cortoclean.