|
Probably the first and most asked question
about soda blasting would be, “is this the
same soda I can buy from the store for my
refrigerator”? Well, all baking soda is
chemically the same (NAHCO3). However, the
larger particles are sieved out for use as
a blast media. Most contain uniform
particle sizes from 90-260 micron and
ingredients to repel moisture that aid in a
consistent flow.
The use of baking soda, as an abrasive, has
been well known for many years. It is one
of the oldest materials used to manually
scrub a variety of things throughout the
household. It has been widely used as a
soap or degreaser. The solubility and the
"safety” of soda, around food and people,
made it ideal for restaurants. It has been
said that the first powdered use was (and
still is) to clean teeth at dental offices
in the 70’s. Armed with only a tiny water
ring and this product, which they blast at
60 PSI, dentists are able to remove stains
and debris. However, the enamel on the
teeth remains undamaged during the process.
Then soda was expanded to micro-blasting
circuit boards (dry, of course) in order to
clean flux off the boards. Many micro-blast
applications are still used today.
The old timers will tell you that soda was
first exposed as an excellent abrasive
during the rebuilding of The Statue of
Liberty for the Centennial (finished 1986).
It was the first large scale use of soda as
a blasting abrasive. It proved to be the
ideal medium for use inside The Statue to
remove coal tar, paint and corrosion. Many
minds tried every way imaginable to remove
the coatings and all failed, until baking
soda was tried. It worked! Next came a full
scale “assault” on finding things to blast
clean. This paved the way for the beginning
of the complete soft abrasive industry;
which also includes materials like sponge
and kieserite.
Soda is not an alternative to a general
purpose blast abrasive. It is more costly
to manufacture. Therefore, more expensive
for the end user, and its soft nature
simply will not achieve the kind of
production rates that an abrasive like
Garnet can render. Still, soda is widely
used in specific areas, and on specific
substrates, and for a number of different
reasons. Some of the important
characteristics that make soda unique in
the world of soft abrasives are as follows:
1. Soft abrasive (does not harm glass,
ceramic, metal, etc).
2. Friable (breaks down on contact).
3. Non-Sparking.
4. Water soluble.
5. Food Grade.
6. Well known chemistry (mostly benign).
7. Recognized as safe to use almost
anywhere.
For example, during fire restoration
projects, soda is used because it will
effectively remove ash and soot from a
sensitive substrate, like wood or brick,
without damaging the surface. In addition,
it also has the ability to neutralize most
of the burn smell associated with
structural fires. Most of the soot infected
materials, before soda blasting, would have
had to be taken out and replaced which is
time consuming and expensive. In auto body
restoration, soda is able to remove several
coats of paint from both metal and
fiberglass body cars without any damage,
while leaving a nice smooth finish. The
higher a pH soda has will cause it to act
as a natural rust inhibitor. Which in some
cases, will hold for months without any
sign of rust. Another plus in auto body
restoration is the soft nature of soda. You
are able to brush by glass, chrome bumpers
and sometimes even plastic moldings in most
cases with little to no damage. This saves
a great deal of time by eliminating the
need to completely disassemble a project
car. Another common application for soda is
Graffiti removal. Again the soft soda is
able to remove paint from brick or natural
stone without damaging the underlying
material. A big plus with graffiti is that
after a soda blast you are able to, in most
cases, just simply rinse the soda away
because it is easily soluble.
However, a trait that is desirable in one
application can be undesirable in another.
When soda is used in applications near
vegetation, great care must be taken to
keep the product contained. The high pH of
soda can cause browning or sometimes even
death to flowers, shrubs and trees. That is
why soda can be chosen for just one or all
of its special unique traits.
The most popular application method of soda
blasting is “dry”. This is the preferred
method for auto body restoration. If one is
considering “dry” soda blasting as a
business, in order to do it right, be sure
to keep in mind the initial cost can be
tough. You will need a large 185 CFM
compressor or bigger and not just any old
sand blasting hopper. Soda blast pots are
unique. They must be capable of metering
the abrasive flow rate down to a minimal
amount to keep cost down, and also it’s
good to be able to adjust the pot pressure
separate from the blast pressure to ensure
a proper consistent flow. Most sand blast
hoppers are unable to…or not designed to do
this. At the same time, the hot compressed
air from the compressor will produce
moisture and must be cooled and run through
a moisture separator. This is necessary
because soda is a water soluble abrasive.
Soda will soak up moisture, when it does it
will become sticky when wet and will build
up inside of your machine’s working
components and hoses. When it dries, it can
become very hard and soda blasting without
a moisture separator can have a blast pot
shut down several times in one day. This of
course, can be extremely costly and time
consuming.
This additional startup cost is unique to
soft, soluble abrasives. For the
entrepreneur who does not have the cash up
front for a system like this, do not be
afraid. Almost every manufacture of this
kind of equipment is able to provide or
point you to a lease or finance program. If
you are looking to soda blast just a few
projects a year, it would not be wise to go
out and buy a complete set up. It takes
time and experience to complete a quality
soda blast project. In this case, it is
best to pay an experienced professional.
Another great way to utilize the unique
traits of soda blasting is in the “wet”
application. This is a piece of equipment
anyone can afford, and most will work with
almost any standard pressure washer.
Introducing soda into a stream of high
pressure water also has its advantages. The
water is able to aid in the cleaning by
getting into places the dry abrasive is
unable to penetrate. Also with this method,
there is absolutely no dust, which can be a
huge problem in the dry application. The
wet method is the preferred technique for a
job like graffiti removal. The down side is
that the wet application, in most cases, is
much slower than the dry.
One might wonder what the future holds for
soda or what soda holds for the future. No
one knows what the future of soda blasting
holds. This industry is growing by leaps
and bounds, with no end in sight. As new
and inventive ways to blast are imagined,
new substrates are now being tested every
day. However, I truly believe the best is
yet to come. What are you thinking of soda
blasting today?
By Gary Birdwell - Universal Minerals,
Inc.
Article published in Cleaner
Times Magazine (April 2007)
|
