The present paper is concerned essentially with the inhibiting action of sodium silicate, and particularly sodium metasilicate, on the corrosion and staining of aluminium surfaces· in inorganic alkaline cleaning systems.
In view of the complexity of both the chemical composition of commercial cleaning compounds and the behaviour of the compounds when in contact with aluminium, a simple laboratory test has been used. Aluminium sheet is immersed in cleaner concentrations of O·1 %, 0·25% and 1% for ½h at 70° to simulate relatively mild cleaning conditions and for 4 h at 100° to simulate severe soaking conditions. Action by the cleaner is assessed by loss of weight and changes in appearance.
