The Dictionary Says:
A blast of air or steam carrying sand at high velocity to etch glass or to
clean stone or metal surfaces. b.
A machine used to apply such a blast. 2.
A strong wind carrying sand along. --sand·blast
sand·blasts. To apply a sandblast to
(a building, for example). --sand"blast"er
Application - Blasting is done with a Air Pressurized Pot where the blasting material (media) is pushed threw
a hose by large amounts of high pressure air volume. It then comes out the end of the hose
through a Blast Nozzle directed at your project to
clean and profile it.
Each media type is different, sometimes only used once and others can
last many, many cycles. It is
typical for all media types that during blasting they fracture, getting smaller
with each use, until they are disposed as dust.
Types Of Media - Puget Sound Coatings uses a variety of
common media types including Garnet,
Aluminum Oxide, Steel Shot & Grit and Glass Bead along with a variety of
other types such as Plastic Media, Sodium Bicarbonate (Soda) and Glass Bead.
Each of the different material types having specific differences between them. One is hardness,
which is most commonly referred to as the
Each of the different blast media types can achieve different results by varying
distance, pressure, direction, and amount of time the item is blasted. Below are some brief descriptions about some of
the more common blast material types that we use.
Garnet - A crystallized mineral, dark red in color, comes in multiple
popular sizes such as the finer 80-grit to the coarser 12-grit. Garnet has a 10 Moh's Hardness and because of it's natural breaking characteristics it
enables us to use the material over and over again. This makes it one of the most
commonly used media types when recycling of the media. It works very well for
removing paint and mil-scale from steel, giving a profile to aluminum,
frosting glass, cleaning stainless steel, wood, plastic and others.
Aluminum Oxide - (Also known as Corundum or Alumina) It is an extremely
hard mineral that is mined and then processed by cleaning, sizing and packaging
for our industry. The
medium brown colored blast grit comes in a large variety of sizes with the
common ones starting at the finer 325-grit to the coarser 12-grit. With a 12 Moh's Hardness this material can be used many times over before becoming spent. This is a very clean abrasive material that leaves a
virtually non-contaminated substrate for coatings that are not surface tolerant.
Steel Shot - A manufactured material from the steel industry where an
atomization process (Click
here for an interesting detail on how Steel Shot and Grit is made) is used to create
small droplets. In further processing it becomes silver in color and is available in a large variety of
sizes from the very small 200 to the very large number 8. Because of the ability
different levels of steel hardness, it has a wide range on the Moh's Hardness
chart of usually between 8 - 10. Most steel shot material is made at the harder
side which makes it extremely durable.
Steel Grit - Similar to steel shot except in the angular grit form. The
color and the hardness is also similar to the the shot, however the impact on the
item being blasted is much different. With shot you get a dimple effect where as
grit you get a divot. This material is greatly used to remove the mill-scale on
steel for coating preparations. It is a very aggressive blast media and cuts
Glass Bead - Spherical shaped beads of glass that are a frosted white color.
Depending on the manufacture, it can come in letter sizes from the finer AH to the
coarser AC or in numbered sizing from the finer 400 to the coarser 10. Glass
beads have a 5 - 6.5 Moh's Hardness making it a very soft material. Because of
the round shape, it leaves a slight dimple effect on the item being blasted. It
works very well on Stainless Steel to clean the staining of weld burns; Gives
glass a fine frosted finish; Cleans aluminum castings; Cleans rubber and
other moulds; Removes anodizing and/or other coatings such as paint resulting in a very fine profile texture on the original substrate. Because of it's
smaller size and softer hardness, glass bead blasting can take considerably more
time compared to other media types.
Plastic Media - Usually a Melamine product although can be made from
other resin material such as Urea, Acrylic and Polyester. Comes in all different colors as plastic does, with a
Moh's Hardness of only 3 - 5 on the scale, it makes this material type so soft that it can
blast paint off from steel without leaving a profile. Plastic media is angular
in shape so as to cut/chip \ paint coatings to the substrate,
leaving the substrate nearly untouched.
At PSC - we have the right equipment and the right blast media material type
and the experienced blasters to meet any blasting need to achieve the
appropriate surface finish for your project. With any process that
follows blasting, such as galvanizing, rubber adhesion, patina, paint and other coating materials.
We regularly work with project engineers, architects, and inspectors
to help achieve the desired results. Quality control before, during and after
blasting is essential for a successful blasting project.
For a full page of Blasting pictures Click
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