Narrow-pore silica gels (Upasil 20) are also available with different color indicators. The degree of saturation is visualized by a change in color.
Different to the past (when indicators based on cobalt chloride have been used), present indicators are environmentally safe and available in a wide range of colors. Upasil indicating silica can be regenerated by heating, thus changing the color back to the active state. This allows the products to be used alone or in combination with, i.e. molecular sieves in gaugeglasses. This allows a simple visual inspection of the adsorption degree. As with the narrow-pored white silicas, a maximum water adsorption of approx. 35% of the silicas‘ weight can be achieved.