Russia has always been a home of cellular glass but Russia failed to exploit their knowledge in time. Recently, Russians developed a new type of cellular glass and it seems that this time there is also a marketing machine working.

Vaporglass ETIZ is based on water glass (liquid glass, sodium silicate solution) and is produced by the evaporation of the water at rather low temperatures. The material is a 100% open cell material, which is claimed to be a fiber free acoustic absorber and thermal insulation (0.045 W/mK) at the same time with a very low vapor diffusion resistance.

But more important, this material is sold at 190 €/m³ for the 120 kg/m³ density version. Larger densities up to 180 kg/m³ are available. Dimensions are 600 x 600 mm, which is rather small. The low density version has a compressive strength of 240 kPa with a thermal conductivity of 0.045 W/mK. It is not mentioned how the thermal conductivity is measured.

A m³ of this 120 kg/m³ material involves 300 kg water glass, which costs 50€. The evaporation of the water to induce the foaming takes minimum another 23€. There is also a stabilizer involved and industrial equipment. A price of 190€/m³ is reasonable. However, I have no idea about the chemical resistance of the product against water and else.

Like already mentioned in a previous post, the chemical department of the technical university of Aalborg is performing very interesting work.

In a  paper about CRT-panel foaming with Manganese oxide, they study the foaming of the glass with a high temperature microscope and made important conclusions about the transition from closed to open cells. By using the percolation limit, they define a temperature window for closed cells.

In the last paper, they foam CRT panel glass, soda lime glass and mixtures of these glasses with Fe2O3. CRT panel glass has the advantage to have a lower thermal conductivity (0.97 W/mK) than soda lime glass (1.1 W/mK) and on top of that, it should be rather cheap because there is no other use possible and the cellular glass manufacturer is paid to absorb the glass.

But in some cases, the glass in contact with Fe2O3 is prone to crystallization, which induces open cells. According to the paper, calcium phosphate is a crystallization inhibitor in this case and the cells remain closed. In our opinion, the use of a crystallization inhibitor to avoid open cells with a mineral foaming agent is the major contribution of this paper. It opens the door to 0.045 W/mK cellular glass at mineral wool prices with equivalent densities.