Bitumen coat with aluminum foil
On the first still sticky bitumen coat, aluminum foil is mounted with generous overlaps. A
second layer of bitumen is applied on the aluminum foil. Gas-tightness is usually higher
compared to the several layers of bitumen without foil.
Water-thinnable dispersion paint
These paints are free from fire- or health hazards. Most of them, however are not gas-tight
and not resistant to moisture. Only those dispersion paints should be used which are
explicitly recommended for underwater use and which form a gas-tight film.
Single- and dual component synthetic resin paints
Synthetic resin paints form elastic, gas-tight coats which can resist rather high physical load.
They are comparably expensive, their use seems only justified if the coating has to resist
mechanical stress. This is usually the case with fixed dome plants. Measurements have
given evidence that the masonry structure of a fixed dome stretches, though minimally, after
filling and under gas pressure.
Paraffin
Paraffin, diluted with new engine oil, is warmed up to 100 -150°C and applied on the plaster
which has been heated up with a flame-thrower. The paraffin enters into the plaster and
effects a 'deep-sealing'. If paraffin is not available, simple candles can be melted and diluted
with engine oil.
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