In the powder coating process , it is important that the metal surfaces of each part are first stripped. Stripping will remove all organic coatings from the parts, such as varnish , glue or paint , as well as oxide or rust .

This step will create a roughness to help the paint adhere to the parts.

The two most commonly used techniques for stripping are sandblasting and shot blasting, but it is important to know the specifics of each.

Sandblasting: a gentle and effective process

Sandblasting involves stripping a part using jets of sand. Sandblasting will remove all impurities on the surface of the metal , while providing a lighter cleaning before moving on to the paint application stage.

The use of sandblasting will allow the part to have a rough surface , which promotes the adhesion of the powder paint and which will give the coating better resistance and a smoother appearance .

Applicable to steel, cast iron, stainless steel, but also aluminum, wood, and stone. Sandblasting is versatile.

The different abrasives used vary depending on the material to be treated. For sandblasting, special sands, quartz sands, and black sands are mainly used.

Note that the grain size is defined according to the type of support, the desired roughness and the stripping intensity.

Shot blasting: an effective and restorative technique

Shot blasting involves blasting a part's surface with shot. As the name suggests, shot blasting involves small steel or stainless steel balls being fired at high pressure, just like sandblasting.

This shot blasting process is perfect for parts with a significant presence of rust or scale, but also salt, dust, oil or grease.

The specificity of shot peening is to consolidate parts with scratches or cracks (not visible to the naked eye). These types of defects can have a negative impact and cause sealing problems, thus altering the performance and lifespan of a part. Shot peening allows cracks to be closed , the surface structure of the part to be improved or modified and thus provides additional protection against corrosion .

Depending on the type of shot used (steel or stainless steel), shot blasting can be applied to all types of ferrous and non-ferrous metals , particularly steel, cast iron, bronze and magnesium.

The shot can have two different shapes. It can be round , which gives it the specificity of stripping by friction and inertia. And it can be angular with a cutting edge, which allows it to offer a better grip profile and clean the parts more quickly. The shot also has the specificity of being economical , because it can be reused after use.

What to choose between sandblasting and shot blasting?

In powder coating, surface preparation is essential to ensure a quality paint coating.

Sandblasting and shot blasting offer specific advantages, depending on the type of part chosen. It is therefore crucial to understand the differences between these techniques in order to choose the most suitable one.

So, what will you choose for your future projects? Sandblasting or shot blasting? 😉

Please do not hesitate to contact us if you have any questions.