Phosphoric Acid 85%
Concentrate

(Crack Flushing and Etching)

Phosphoric acid is used as a cleaner by construction trades to remove mineral deposits, cementitous smears, and hard water stains. It is also used as an ingredient in some household cleaners aimed at similar cleaning tasks.

Mix 1 litre with 38 litres (10 gal) of water to produce a standard crack injection acid solution.

Pure 75-85% aqueous solutions (the most common) are clear, colourless, odourless, non-volatile, rather viscous, syrupy liquids, but still pourable. Phosphoric acid is very commonly used as an aqueous solution of 85% phosphoric acid or H₃PO₄. Because it is a concentrated acid, a 85% solution can be corrosive, although not toxic when diluted.

Phosphoric acid may be used by direct application to rusted iron or steel tools or surfaces to convert iron(III) oxide (rust) to a water soluble phosphate compound. Care must be taken to avoid acid burns of the skin and especially the eyes, but the residue is easily diluted with water. When sufficiently diluted it can even be nutritious to plant life, containing the essential nutrients phosphorus and iron. It is sometimes sold under other names, such as "rust remover" or "rust killer". It should not be directly introduced into surface water such as creeks or into drains, however. After treatment, the reddish-brown iron oxide will be converted to a black iron phosphate compound coating that may be scrubbed off. Multiple applications may be required to remove all rust. The resultant black compound can provide further corrosion resistance (such protection is somewhat provided by the superficially similar Parkerizing and blued electrochemical conversion coating processes.)

Read full MSDS before using!