Condensation is formed when moisture in the atmosphere changes back
to water as it comes into contact with a surface at a temperature below
the 'dew point' of the surrounding air.
Water droplets on the surface of the glazing reduce light
transmission, and, if they fall, can spoil plants or damage sensitive
goods and equipment beneath. Multiwall PC (i.e. Polygal Anti Fog) sheet has a special one-side coating
that inhibits the formation of condensation droplets. The coating lowers
the surface tension and the drops form a thin layer of water over the
whole surface of the sheet.
When the sheet is correctly installed, this thin, transparent water
film runs off the sheet surface into the profile drainage system without
falling to the ground and without significantly affecting the light
transmission values of the glazing.
Figure 20 shows a typical condensation predication chart showing the
relationships between internal and external temperatures, relative humidity
and the U-value. The dotted lines on the chart illustrate clearly how
glass with a high U-value is more prone to condensation than the
Inside temperature: 68 F
Outside temperature: 14 F
Condensation will occur on:
||Multiwall 25 mm at a humidity content of:
||Multiwall 6 mm at a humidity content of:
|| Glass at a humidity content of:
Periodic cleaning using correct procedures with compatible household
cleaners is recommended to prolong service life.
For general cleaning, it is recommended that the following instructions
be adhered to.
|Cleaning Agents Which
Have Been Found to be Compatible Polygal Sheet
|VM&P grade Naptha
Procedure 1 - Small Areas
1. Rinse sheet with lukewarm water.
2. Wash sheet with a solution of mild soap or household detergent and
lukewarm water, using a soft cloth or sponge to loosen any dirt and
3. Rinse with cold water and dry with a soft cloth to prevent water
Procedure 2 - Large Areas
1. Clean surface with a high pressure water and/or steam cleaner.
2. Use of additives to the water should be restricted to those
compatible with Polygal sheet.