Stainless steel consists of iron with added alloy metals. The most common are:

• Chrome
• Nickel
• Molybdenum
• Titanium

The alloying metal react chemically with the oxygen in the air, forming a thin layer that protects the iron from corrosion.

When stainless steel is machined, the protective surface layer is penetrated, this is seen as dark tarnish around weld seams, cutting edges and burnt sanding dust.

The pickling process must remove harmful tarnishes - both the oxides and the underlying chromium-plated layer, after which the protective layer can be restored.

The pickling can be done either as dip pickling or as spray pickling.

Glass-blasting is very similar to the probably more well-known surface treatment sandblasting. However, there is a big difference between glass-blasting and sandblasting, both in relation to the material used and in relation to where it is used.
In sandblasting, sand grains are used which are sharp-edged, whereas in glass-blasting, spherical glass beads without sharp edges are used. Glass beads do not have an abrasive effect on the surface material, but simply remove impurities so that the surface becomes uniform with a nice matte finish.

We use glass beads with a diameter from 150-250 µm (1000 parts millimeter). When glass-blasting stainless B2 plates, a surface roughness Ra of approx. 45 μm. Due to the surface roughness, glass-blasted surfaces are not suitable for food contact.

Surface treatment with glas
Helge Bruhn A / S has one of the industry's most modern glassblasting systems for glassblasting of stainless steel and aluminum. The plant is also among the largest and most efficient, which means that we can also handle very large items of up to (WxHxL) 2.4 x 2.4 x 6m.

The glassblasting plant is used both for post-processing of the company's own processed items and for direct subcontractor work.

Helge Bruhn A / S is one of the industry's preferred suppliers of glass-blasting, partly due to the company's extensive experience with special tasks in stainless steel and surface treatment of the items. Many experience problems with, among others imbalances in their products after glass-blasting because e.g. an incorrect working pressure has been applied to the system during the glass-blasting.