Melting Ice With Salt - FAQ From Buyers

Cold icy weather creates major safety problems on paved surfaces for
a large part of the world during the winter season. Salt is by far
the most popular material used around the world for melting ice.
Because of the proliferation of choices, buyers are becoming more and
more confused as to which salt to buy. This article answers the
frequently asked questions (FAQ) from buyers regarding the usage of
salt to melt ice. These FAQ were accumulated over many years by a
minority operated woman owned janitorial supply company.1) Is salt
another name for rock salt? ANS: Yes. The term salt is commonly
used referring to table salt, sea salt or rock salt (Halite).
However, any chemical compound formed by neutralizing a base and an
acid is technically a salt. Salt compounds are held together by ionic
forces between two or more elements. It is the ionic properties of
the salt compounds that allow them to melt ice. The chemical compound
for table salt, sea salt and rock salt is Sodium Chloride (NaCl).2)
Will salt kill my vegetation? ANS: Yes, but only in very high
concentration. Care must be taken to minimize the build-up of salt
around vegetation. Any damage to the soil is usually temporary since
normal precipitation quickly dilutes the salt.3) Should I use a
non-salt product? ANS: No, unless metal corrosion is a major concern.
Salts have been overly criticized for their effect on the
environment. The fact is that salts dilute quickly during spring rain
and snow melt minimizing the potential damage to vegetation and
animals. Most non-salt products contain urea, glycols or fertilizers
that are much more damaging to an ecosystem because these products
cause fish kill.4) What are my salt choices? ANS: The two basic
choices include: 1) inorganic salts such as Sodium Chloride (NaCl),
Potassium Chloride (KCl), Magnesium Chloride (MgCl2), and Calcium
Chloride (CaCL2), or 2) organic salts such as Sodium Acetate (NAAC),
Potassium Acetate (KAC), and Calcium Magnesium Acetate (CMA).5) Are
inorganic salts safe? ANS: Yes, but only when the salt is used as
instructed. Inorganic salts are more corrosive to metal. Some of the
more aggressive inorganic salts can burn skin and pet paws. "Concrete
corrosion" from the usage of inorganic salts is not really a corrosion
process. "Concrete corrosion" is a progressive cracking process
caused by the brine freeze/thaw cycle as temperatures move above and
below the freezing point. The inorganic salts are less expensive and
therefore more frequently used by the majority of buyers. When the
package instructions are followed (using gloves, keeping away from
unprotected metal, avoiding fresh concrete, following application
rates, etc.), the inorganic salts are very safe.6) Is chloride in
inorganic salt safe? ANS: Yes. The chloride ion present in
inorganic salts comes from the element chlorine which is one of the
most abundant elements found on the planet. The oceans contain the
largest amount of chlorine in the form of sodium chloride. Chlorine
is used to disinfect the water in rivers, water treatment plants and
swimming pools. As with many natural elements, chlorine in very high
concentrations can be dangerous.7) Are organic salts safe? ANS:
Yes. Organic salts decay naturally in the environment while having
minimal effect on the fish kill issue caused by non-salt products. CMA
is no more corrosive to metal than water and will not burn skin or pet
paws. Since acetate products are much more expensive than the
inorganic salts, usage of acetate products is very limited. Salt
granules are often coated with acetates to provide more corrosion
resistance around metals. Acetate coatings can also speed up the
melting process.8) Will rock salt work for me? ANS: Probably not.
It lacks the performance of other salts and is not effective below +20
degrees F. It melts slower. It allows the freeze/thaw cycle to occur
at +20 degrees F. Most customers don't like the white residue left
behind when rock salt brine dries up. To work well, it requires lots
of traffic to produce heat from friction. Improved corrosion
protection on automobiles and bridges has made rock salt acceptable on
road surfaces in areas where temperatures do not get extremely low.9)
Is calcium chloride the strongest salt? ANS: Yes. It does the best
job melting ice but has some disadvantages. Calcium chloride like
rock salt will leave a white residue on carpet when tracked inside.
It is the most aggressive salt when it comes in contact with skin or
pet paws. Most significantly, it is the most expensive of the
inorganic salts. If an application does not require the extreme low
temperature (-25 degree F) melting power, it may not be the most cost
affective solution.10) Is magnesium chloride a pet friendly salt?
ANS: Yes, most people find that magnesium chloride works best around
their pets while still providing good sub-zero melting power (-13
degrees F). Magnesium chloride granules contain 50% water which
reduces the tendency to stick to pet paws and dilutes the salt to
reduce burning. Even if ingested by a pet, the diluted granules would
be less harmful to the pet.11) Is potassium chloride a salt and a
fertilizer? ANS: Yes. Potassium chloride promotes root growth
making it a good fertilizer. This does not mean that it is the safest
salt for the environment. As explained previously, fertilizers when
heavily used as an ice melter can cause fish kill, which is a very
serious problem for the ecosystem.12) How do I choose the best salt?
ANS: Often a mix (referred to as an ice melt blend) is the best
choice. Manufactures have now developed processes to both blend and
coat salt granules to get optimum results depending on the
application. The buyer should be aware that it is not the marketing
language or fancy packaging that makes ice melt blends better. It is
the ingredients.13) How do I determine the salts used in an ice melt
blend? ANS: The Material Safety Data Sheets (MSDS) will provide a
list of ingredients. However, the MSDS often does not give the
formulation (percentage of each ingredient). Manufactures consider
the formulation proprietary.14) How do I determine the percentage of
each salt in an ice melt blend? ANS: One way would be to take a
sample to a laboratory for a chemical analysis. This is generally
done for very large commercial contracts where the contract specifies
the percentage of each ingredient required by contract. Often
comparing the price of a product to the ingredients that are listed on
the package will allow for a good "guess-timate". Less expensive
products always contain greater proportions of less expensive
ingredients and smaller proportions of more expensive ingredients.15)
What is the difference between Eutectic Temperature (ET) and Minimum
Effective Temperature (MET) of a salt? ANS: ET is the laboratory
measured melting point for the salt compound. For salts to work for
melting ice, they must go into brine (salt saturated solution). The
MET is the temperature of the brine at which freezing first occurs. A
buyer should be cautious because some ice melting products will list
ET as the minimum melting temperature.16) What determines the MET for
a mix of salts? ANS: Each salt has its own MET. Because there is
very little interaction among the basic inorganic salts, the MET is
only raised or lowered depending on the proportions of each salt used
in the mix. Example: When it is concluded that the percent of CaCl
in an ice melt blend is only a trace level, no improvement in MET is
to be expected from the CaCl.17) How does MET affect my buying
decision? ANS: MET is directly proportional in most cases to the
price of a product. Paying for a product that will provide subzero
protection for an application where the thermometer rarely drops into
the teens is not very cost affective.18) Where can I buy CMA? ANS:
The question should be "Why should I buy CMA?" Pure CMA is 30 times
more expensive than rock salt and has the same MET as rock salt.
There are very few applications for such an expensive product.
Airports are probably the only exceptions because of the need to avoid
metal corrosion at all cost. Very few distributors sell 100% CMA.
Buyers need to understand that inexpensive CMA products usually
include a less expensive salt or urea that has been coated with
CMA.19) Is urea a salt? ANS: No. Urea is a natural product high in
nitrogen that comes primarily from the urine of mammals. In an effort
to market earth friendly products, many ice melt blends contain
significant proportions of urea mixed with salts, fertilizers, etc.
Caution must be taken in using urea products because of the fish kill
issue. Various forms of traction materials (sand,
cinders,calcianated clay, etc.) are often added to urea because urea
brine is very slippery.20) Can salt damage asphalt surfaces? ANS:
Yes. The potential for damage exists but is not very likely. Asphalt
is a more compliant material than concrete. The freeze/thaw cycle
that causes concrete to scale does not occur on asphalt. However,
when the salt brine works its way into asphalt cracks and freezes, the
ice expansion can cause crack propagation on older asphalt that is
less compliant.