The water-intensive cleanup is necessary
to get rid of the residue on the surface that has not reacted,
as well as the byproducts of the reaction. "It's a hazardous
material until it's all cleaned up," Sullivan says.
The brown residual material typically contains chrome, which
is right up there with mercury, lead and other heavy metals,
he says. "OSHA and other government agencies don't want
that to get into our streams or groundwater."
By
law, contractors must follow local regulations on how to
deal with the wastewater. Compliance could involve vacuuming
it up and treating it. Some contractors mix the residual
water with kitty litter or cement and throw it away. Once
dry, the residue is no longer a threat.
There are also
hazardous-material shipping concerns, says Keith Boudart,
sales manager for Butterfield Color, which means an additional
cost for handling. And because of the acid content, you have
to use plastic sprayers instead of metal that can corrode.
Rob Ellis, president of SRI Concrete Products, notes that
acid stains are no stronger than muriatic acids that anyone
can buy from big chain retailers. "You should take the
same precautions you would applying a simple acid etch."
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