Shot Blast
Our 7 metre shot blast room lets us prepare a wide range of large components to Sa 2½. Good blast cleaning is the foundation of any paint or thermal spray system, because it gives the coating the best possible grip.
Why blast before coating?
New steel comes from the mill covered in mill scale, a thin and flaky layer of iron oxide. Older steel usually has rust, grease or old paint on it as well. Any coating put over the top is only as good as the surface underneath, and once that starts to lift, the coating comes away with it.
Blast cleaning strips all of that back to bare metal and leaves a slightly rough surface for the new coating to key into. It's the single biggest factor in how long a finish lasts.
What Sa 2½ means
Sa 2½ is a cleanliness grade from ISO 8501-1, the standard the industry uses to describe blasted steel. At Sa 2½ there's no mill scale, rust, paint or dirt left that you can see, only light staining. It's the grade most paint and thermal spray specifications ask for, so if your job has a coating spec, there's a good chance this is what it calls for.
Iron grit
Metabrasive chilled iron grit (Metablast) is a fast-cleaning, high-performance cast iron abrasive. It's melted in an induction furnace, and its low residual elements and tightly controlled chemistry give it a long service life.
It can be used in wheel blasting machines but is mainly used for air blasting. Its benefits include:
- a controlled etch and the required surface finish
- a fast cleaning rate
- less dust, so better visibility for the operator
- longer abrasive life, often 35% more than standard chilled iron grit
- lower overall blasting costs
- effective removal of old paint
Metablast is made to ISO 11124-2:1993 (BS 7079: Part E2: 1994), in grit sizes from G05 (0.125mm) to G80 (2.0mm).
What we blast
- new steel fabrications that need preparing for powder coating or zinc spray
- rusty or previously painted items that need stripping back before they're refinished
- gates, railings, balustrades, frames and structural sections
Our blast room is 7 metres long, so long sections and large fabrications can be done in one go.
Blasting and coating on one site
We blast, powder coat and zinc spray in the same workshop. Freshly blasted steel can start to rust again surprisingly quickly, so being able to move it straight on to coating makes a real difference to the finish. It also means one company is responsible for the job from bare steel to final coat.
Getting a quote
Let us know the sizes and quantities, what's on the surface now (mill scale, rust or old paint) and what the steel will be coated with afterwards. Photos or drawings help too, so mention them when you send us a message.