Acid Etching of Concrete

The majority of concrete surfaces should be acid etched before painting. This method of surface preparation carries out two functions: 1. Etches the concrete surface, removing loose particles giving the paint a better footing on which to adhere. 2. Neutralises excess free alkali which may cause failure of the paint system. The concrete surface is etched by the application of a diluted hydrochloric acid solution. A satisfactory solution may be prepared by adding one part of Commercial Hydrochloric Acid to four parts of water by volume. CAUTION: ALWAYS ADD ACID TO WATER – NEVER WATER TO ACID. ALL NECESSARY SAFETY PRECAUTIONS SHOULD BE TAKEN WHEN HANDLING ACIDS. The acid solution is liberally flushed over the concrete and a bubbling action should be evident. The solution should be left in contact with the concrete for about 15 minutes, after which the surface should be hosed off, or liberally flushed using clean, fresh water. Brooming off the surface whilst flushing will also help to remove any loose particles. Check the surface is Ph neutral by using an inexpensive ph test, available from most pharmacies. The surface must be thoroughly dry before painting – a drying period of up to one week is recommended. For more information about the standards for the painting please see our web-site: https://painters.edu.au/Training-Reso... For training in the correct surface preparation of surfaces check our web-site: https://painters.edu.au/Training-Cour...