Dry-Ice Blasting for Mold Remediation
Dry
ice blasting accomplishes mold remediation more completely
than mechanical abrasion. Dry ice blasting does not require
chemicals and does not create a toxic dust hazard from mold
remediation operations, such as, when manually scraping and
sanding. The range of available nozzles for dry ice blasting
equipment enables us to access tight corners, and in many
cases, clean mold from areas inaccessible to hand tools,
such as inside corners of wood framing trusses and joists.
Note: Mold remediation to attic ceilings with deep mold
staining is best accomplished with our chemical method
versus dry ice blasting. This is because dry ice blasting
cannot penetrate deep enough into the wood to remove the
dark mold stains.
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Dry-ice is Safe on Electrical |
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Dry Ice Blasting is a
non-conductor of electricity, so live electrical
equipment and wiring does not have to be removed or
de-energized during the remediation process.
Dry Ice Blasting leaves a dry surface, eliminating
the need for drying downtime and making it safe on
electrical components and wiring, junction boxes,
power panels, ductwork, and plumbing.
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Dry-Ice Blasting Before & After Pictures
on a 7/2019 attic mold remediation job
this attic ceiling had a high level of aspergillus mold
growth
Attic Ceiling Mold Removal - Before
Pictures
(click to expand)
Attic Ceiling Mold Removal - After
Pictures (same attic)
Dry-Ice Blasting - How it Works
Dry
ice blasting for mold remediation uses four physical
properties of air-propelled dry ice pellets: velocity,
abrasion, thermal shock, and evaporation. Dry ice is solid
(frozen) carbon dioxide. For blasting uses, dry ice is
manufactured in pellets of various sizes appropriate to the
substrate to be cleaned. The pellets are hurled from a
blasting gun by air pressure, which provides the velocity.
When the pellets strike the surface to be cleaned, three
things happen. First the velocity of the pellet strikes the
substance to be removed. Because dry ice is at a temperature
of -109 degrees F., the thermal shock helps loosen and lift
the substance to be removed. Finally, the dry ice pellet
flashes into carbon dioxide gas, providing more lift to the
substance to be removed. The carbon dioxide gas is harmless,
leaving no cleaning material such as sand or solvents to be
cleaned up after the cleanup.
Complete mold removal and remediation
requires solving the moisture problem that enabled the mold
to grow in the first place. A mold needs food, such as wood;
moisture; and a temperature range favorable to the growth of
the specific mold organism. Grinding, sanding, or
wire-brushing to remove mold growth does not sanitize the
surface and kill the mold spores. Without dry-ice blast
cleaning,
a biocide/sanitizer/cleaner is needed to kill the mold spores. Dry ice
blasting will almost rid the need for biocides and thus,
enhance occupant and worker safety.
Its a great option for mold remediation in areas with a
chemical sensitive individual.
high density dry-ice pellets
Dry-Ice Blasting for
Fire Damage Restoration
Dry Ice cleaning is also extremely effective in removing toxic
residues, such as, soot and associated smells after a fire.
The Dry Ice Blasting produces
a more thorough cleaning by reaching areas other methods
cannot. The blast stream reaches the smallest cracks, creases and wood
joints where wire brushes or hand cleaning cannot.
This allows for a better evaluation of the damage
otherwise hidden by smoke or soot, which is
important after a fire for structural inspection,
health and general maintenance.
Dry-Ice-Blasting - Technical Information
Pellet Kinetic Energy
The dry-ice blasting process incorporates high velocity
(supersonic) nozzles for surface preparation and coating
removal applications. Since kinetic impact force is a
product of the pellet mass and velocity over time.
Even at high impact velocities and direct head-on impact
angles, the kinetic effect of solid CO2 pellets is minimal
when compared to other media (grit, sand, PMB). This is due
to the relative softness of a solid CO2, which is not as
dense and hard, as other projectile media. This
characteristic is a plus. This prevents damage to the wood
surfaces and electrical wiring. Also, the pellet
changes phase from a solid to a gas almost instantaneously
upon impact, which effectively provides an almost
nonexistent coefficient of restitution in the impact
equation. Very little impact energy is transferred into the
coating or substrate, so the blasting process is
considered to be nonabrasive.
Thermal Shock Effect
Instantaneous sublimation (phase change from solid to
gas) of CO2 pellet upon impact absorbs maximum heat from the
very thin top layer of surface coating or contaminant.
The very rapid transfer of heat into the pellet from the
coating top layer creates an extremely large temperature
differential between successive micro-layers within the
coating. This sharp thermal gradient produces localized high
shear stresses between the micro-layers. The high shear produced over a very brief expanse
of time causes rapid micro-crack propagation between the
layers leading to coating final bond
failure at the surface of the substrate.
Thermal-Kinetic Effect
The combined impact energy dissipation and extremely
rapid heat transfer between the pellet and the surface cause
instantaneous sublimation of the solid CO2 into gas. The gas
expands to nearly 800 times the volume of the pellet in a
few milliseconds in what is effectively a "Micro-explosion"
at the point of impact.
The "Micro-explosion," as the pellet changes to gas, is
further enhanced for lifting thermally-fractured coating
particles from the substrate. This is because of the
pellet's lack of rebound energy, which tends to distribute
its mass along the surface during the impact. The CO2 gas
expands outward along the surface and its resulting
"explosion shock front" effectively provides an area of high
pressure focused between the surface and the thermally
fractured coating particles. This results in a very
efficient lifting force to carry the particles away from the
surface.
