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Grit Blasting

To present a clean and perfect *profile for bonding both wet coat paints, intumescents and dry thermal spray metal finishes, it is vitally important that all substrates are first cleaned and blasted to remove any pre-existing protective coating and corrosion.

 

What is Grit Blasting?

Grit Blasting is a surface treatment where abrasive particles are fired through a nozzle at high pressure, using a propellant such as compressed air or liquid. This process is used for cleaning existing coatings or to creating a profile for good adhesion

Different media can be used for the grit blasting, depending on a number of considerations:

·        What the surface material is that requires cleaning.

·        What surface contaminants need to be removed i.e. rust, paint etc

·        Any cost or time restrictions.

 

Blasting Services at Ripblast

Our blasting services all take place on site, in our specialist, dedicated workshops.

All large item, aluminum oxide blasting, takes place in our dedicated  workshop # 2 with it’s state of the art ventilation and grit recovery systems. Multi media blasting, glass bead, garnet etc, is carried out in Blast Room #10.

Please feel free to contact us about your blasting requirements. No job’s too small.

*The blast dwell time or number of sweeps to which the substrate is subjected.

Grit Blasting

Our preferred universal blast media, is commercial grade aluminium oxide, an inert abrasive, which achieves the full range of blast standards including *SA1, SA2, SA2.5 and SA3,  on all substrates including stainless steel and duplex for both wet and thermal spray metal coatings. 
By controlling the air and feed settings at the pot, our skilled blast operatives can accurately and without surface damage, remove coatings and surface deposits from many of the more sensitive surfaces. Please contact Lee, for further information on this subject.

*Used to determine the blasting standards on the 4 Rust Grades A,B.C & D for ISO 8501-1.

Bead Blasting

Bead blasting is the process of removing surface deposits by applying fine glass beads at high pressure without damaging the surface.  It is mainly used on vehicle body panels to remove paint in order to reveal damage caused by rust. In the case of auto body work, the bead blasting media is generally preferred over grit, as grit blasting tends to create a greater surface profile.

Bead blasting is often used to create a uniform polished surface finish on machined parts. Read more on our bead blasting page.

There are other forms of media that are used in grit blasting, such as:

  • Silicon carbide is extremely hard and can be recycled many times. It is ideal for etching stone or glass.
  • Steel shot can be used to improve metal surfaces as well as clean them. The ball shape of the shot helps to provide compressive strength to metal surfaces.
  • Plastic grit media is relatively soft and regularly used in aerospace and automotive applications. It is best for stripping coatings from delicate metals, composites and other plastics.
  • Pumice is a natural form of media that is a light and mild abrasive. It is therefore used to maintain protection of the surface being cleaning.
  • Other natural medias can be made from corn cobs and walnut shells. These provide excellent cleaning and stripping without damaging the underlying substrate.
  • Specialist media can be sourced and used for certain specialist projects. If you have any special requirements, please contact us.

Aluminium Oxide​

Glass Bead

SA 2.5 - Near White Metal​
Glass Bead

Preparation of steel substrates before application of paints, thermal coatings and related products — Visual assessment of surface cleanliness.

The Four Rust Grades as defined by ISO 8501-1

Rust Grade A

Grade A

Surface mostly covered with adherent mill scale, with little or no rust.
Rust Grade B

Grade B

Mill scale has begun to flake, rust has started to form.
Rust Grade C

Grade C

Mill scale has rusted away or can be scraped off easily and slight pitting has taken place.
Rust Grade D

Grade D

Mill scale has rusted away and general pitting can be seen with naked eye.

Four Visual Grades of Cleanliness after Blasting as defined by ISO 8501 – Based on Grade D Surface Rust.

SA1 Brush Off

SA 1 - Brush Off

Loose mill scale, loose rust and foreign particles are removed.
SA2 Commercial

SA 2 - Commercial

Mill scale, rust and foreign particles are substantially removed and grey metal is visible.
SA 2.5 - Near White Metal​

SA 2.5 - Near White Metal

Mill scale, rust and foreign particles are removed to the extent that only traces remain in the form of spots or stripes. The cleaned surface will show varying shades of grey.
SA 2.5 - Near White Metal​

SA 3 - White Metal

Visible mill scale, rust and foreign particles are entirely removed. The cleaned surface should have a uniform metallic colour but may show varying shades of grey when viewed at different angles.

Loosely-adhering material: 0%
Tightly-adhering material: 100%
Stains, streaks, shadows: 100%

Loosely-adhering material: 0%
Tightly-adhering material: 0%
Stains, streaks, shadows: 33%

Loosely-adhering material: 0%
Tightly-adhering material: 0%
Stains, streaks, shadows: 15%

Loosely-adhering material: 0%
Tightly-adhering material: 0%
Stains, streaks, shadows: 0%

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