The outer face of three samples (lenses or samples of material) shall be heated to 50 °C +- 5 °C and then immersed for five minutes in a mixture maintained at 23 °C +- 5 °C and composed of 99 parts distilled water containing not more than 0.02 per cent impurities and one part alkylaryl sulphonate.
The outer face of three samples (lenses or samples of material) shall be heated to 50 °C +- 5 °C and then immersed for five minutes in a mixture maintained at 23 °C +- 5 °C and composed of 99 parts distilled water containing not more than 0.02 per cent impurities and one part alkylaryl sulphonate.