|
 Water
Based Silane on Brick
In last months issue, we offered
answers to questions about water based silane technology.
There still seems to be some confusion with regards to the
application of water based silane technology on brick. I recently
sat down with one of our approved applicators and discussed
this in more detail:
Q. Aren't water based products
the newest technology?
A. No. Back in the 1960's and 1970's
most experts cautioned or outright banned the use of water
repellent sealers on brick masonry. The reasons were justified;
these 1960's sealers reduced the natural water vapour transmission
of the masonry, discoloured over time (sometimes turning white)
and had limited life cycles. The technology at that time was
based on stearates, mineral waxes, silicones and acrylics.
Most of these technologies are water based.
In the late 1970's and early 1980's,
solvent-based silane and siloxane technology started to be
the preferred repellents for masonry. They had the advantage
of good performance and longevity, plus none of the negatives
of the older technology. It is not uncommon (we can show you
some) to have brick masonry building treated 20 years ago
with a solvent based silane that's still working. Solvent-borne
systems ruled the marketplace.
As the VOC regulations became more
common place, some manufacturers simply went back to the 60's
technology, updated the emulsion system, and added some silane
and/or siloxane.
Q. Why can't I just use a water
based silane on my masonry building?
 A.
Silane emulsions (20% and 40% active) have been sold since
the mid-80's. Primarily used on concrete, their effectiveness
on masonry is iffy. The reason is that silanes react with
moisture in the masonry. This reaction results in the chemical
bonding that make silane such a durable material.
With silane emulsions, you have to prevent a premature reaction
of the silane and water in the drum. Various methods are used
for this including pH buffers and stabilizers. If applied
to concrete, the silane emulsion breaks due to the concrete's
high alkalinity (high pH). But, on less reactive substrates
such as brick masonry, the silane won't react.
The way around this is to use emulsions
with low solids content on brick masonry. Most emulsions for
masonry have between 5% and 15% active material. This increases
emulsion stability (shelf life) and less stabilizer can be
used. These low solids emulsion work better than their higher
solid counterparts on masonry. Neither works as well as the
old 40% solvent-based silane systems.
Q. Since I won't be able to use
40% solvent based sealers after the VOC laws change and the
water based products don't perform as well, what can I use
to treat masonry?
A. 100% silanes can be used to treat
masonry. These products can be applied at low temperatures
(about -10°C), don't leave a residue on glass, don't darken,
leave lap marks, turn white and meet the Canadian VOC regulations.
100% silanes were originally designed for concrete decks for
extended service life; they have been sold in Canada for over
20 years. The new class of 100% silanes work on the less reactive
brick masonry. They are 100% breathable and can be applied
over most previous silane and siloxane treatments.
Q. 100% silane sealers sound expensive,
What's the cost for sealing brick masonry?
A. Per litre, 100% silanes are more
expensive than low solids water based products. Compared to
solvent based, they are less expensive on a silane to silane
content basis. When looking at applied cost, the 100% are
much more cost effective. Protectosil
CHEM-TRETE BSM 400 is one of the few sealers that does
not leave a residue on glass and metal. This saves a lot on
application cost. Plus, they last at least 20 years.
Click
for more information regarding the Canadian VOC regulations
|
1)
A cleaning system using a special detergent (ORS-D.);
2)
An oil resistant primer coating (ORS-C) with a sand broadcast.
EMSHIELD
WFR2 (Wall, Fire-Rated 2-Hours) is the second in a series
of fire-rated expansion joints being released by EMSEAL. It
can be joined with 
For
more information on the bylaw click this link: 
