temperature and are both ‘polar’.
Polar substances generally dissolve in
water. On the other hand ‘non-polar’
substances, such as oil, petrol, or wax,
don’t. Polar substances are ‘hydrophilic’:
they combine with water and watery
solutions. Non-polar substances are
‘hydrophobic’: they repel water and
watery solutions. Siloxa-Tek 8510 is
both, so some very clever chemistry is
involved, as it repels both water and oil.
Preparing the concrete
My shed has been mainly used for
storage, including hay, and it was
dusty and dirty, so a thorough clean
of the concrete was needed. It is more
than 10 years old and, despite major
earthquakes, has a very good concrete
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old workmate Kevin, who had done
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I commenced prepping and used a hot
solution of laundry detergent powder in
water and a long-reach scrubbing brush
which did a good job of lightening the
surface. Using powder, rather than
a liquid detergent, was probably a
mistake. I have read that the powder
is about 50 per cent washing soda —
sodium carbonate (Na 2 CO 3 ) — which
is added as a water softener. Although
I rinsed the soapy water off with a
Karcher water blaster, some of the
washing soda may have remained. It
reacts with acid in a similar way as the
carbonates in concrete and so may have
reduced the effectiveness of the acid
used to etch the concrete. f
The total area is about
40m^2 and I was going
to do about a third
of this at a timeRolling out the test strip —
Siloxa-Tek 8510 on the roller