Moisture double glazing

The use of silicone sealant for insulating glass (double glazing) gives excellent adhesion to glass which is unaffected by UV radiation but which must be used with a waterproof sealant such as polyisobutylene to reduce moisture vapour transmission (MVT). The use of silicone sealant alone will result in water condensation inside the unit in a relatively short period of time and would permit water vapour to be absorbed into the unit and eventually exhaust the desiccant used in the space. The use of small beads of polyisobutylene as a primary seal (Figure 6.3) reduces the MVT to a very low number, thus correcting the one deficiency of silicone (Panek and Cook, 1984). Sealants for SSG systems may be applied on... 

Figure 6.3 The use first of a waterproof seal of polyisobutylene in double glazing to reduce the moisture vapour transmission (a) outer view (b) section...

Insulating glass or double glazed units consist of two panes of glass separated by a spacer and all are held together by edge Sealants (Fig. 1). These sealants seek to exploit the specific properties of low moisture vapour transmission, low inert-gas transmission and high durability of the sealant used (see Durability fundamentals). 

The durability of double glazing sealants is normally assessed by measuring the rate of moisture ingress into the cavity. This can be done by measuring the amount of water absorbed by the desiccant or by determining accurately the internal dew point. The former... 

---