Steel Surface Finishing Standards Chart
The finish surface achieved by abrasive blast cleaning depends upon the original surface condition as well as the type of abrasive blasting equipment, size, hardness, type and abrasive shape.
Our steel surface finishing standards chart is the best way to measure the original surface condition and the finish surface achieved. You can click on the image below to see a full size, printable version.
THE ORIGINATING SURFACE CONDITION OF STEEL IS:
- Steel surface largely covered with adhering mill scale by little, if any, rust.
- Steel surface which has begun to rust and from which the mill scale has begun to flake.
- Steel surface on which the mill scale has rusted away or from which it can be scraped, but with slight pitting visible under normal vision.
- Steel surface on which the mill scale has rusted away and on which general pitting is visible under normal vision.
SURFACE CLEANLINESS IS DIVIDED INTO FOUR GRADES:
- SA 1 Brush off.
- SA 2 Commercial.
- SA 2-1/2 Near white metal.
- SA 3 White Metal.
Besides cleanliness of the steel, consideration needs to be given to the etch or profile roughness created by the impact of the abrasive on the steel surface.
THE SUBSTRATE PROFILE IS REGULATED BY:
- Shape, type and grading of abrasive.
- Blasting method and velocity of abrasive impaction.
- Steel condition prior to blasting. The etched profile of the surface enables adhesion of the protective paint coatings. If the level at which this is achieved is too severe it will cause a waste of paint. If too light, it may cause a lack of adhesion.
The best method of obtaining a profile specification is to ensure the correct blasting equipment and method are combined with the correct abrasive. Once these requirements have been decided upon, the selection of method, equipment and training of personnel should be instigated.
Equipment used for surface preparation must be extremely reliable and simple to use.Operation information and training should be up-to-date.
Airblast has become the industry standard for manufacturing and supplying surface finishing equipment worldwide through a network of branch-offices as well as distributors.