Standards Development

Scope

This document describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles, that is intended for laboratory development purposes only, to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The apparatus used is a cylindrical vessel with a volume surface ratio of 3:1 in which two enamelled specimens are tested.

NOTE 1 The test method was initially set up for determination of the resistance of vitreous and porcelain enamels to a hot sodium hydroxide solution. Within the scope of this part of ISO 28706, the resistance of other alkaline liquids can be tested.

NOTE 2 This part of ISO 28706, which uses a cylindrical vessel, is generally used for tests carried out on vitreous and porcelain enamel coatings for enamel developments regarding alkaline attack.

Purpose

This document was developed to provide specifications for a standard test method for chemical corrosion by alkaline liquids. While EN ISO 28706-4 deals with chemical corrosion by alkaline liquids that prohibits inhibitory effects, ISO 28706-6 deals with rapid information on alkaline corrosion. The liquid volume is smaller and the apparatus is smaller. Therefore, three times as many apparatuses fit into the water bath for temperature control. In addition, each apparatus contains two test plates. While EN ISO 28706-4 only allows two test devices to fit into the water bath, meaning that only one test with one repetition can be performed, EN ISO 28706 allows three parallel double determinations to be performed in the same time period. In addition, since the concentration of sodium hydroxide is ten times higher, clear information about sodium hydroxide resistance can be obtained quickly, which is a great advantage for development of vitreous or porcelain enamels.