Ceramic vs Plastic Tumbling Media

The selection of tumbling media for a particular application depends not only on the type of material/metal being tumbled but also on the finish required for the next step(s) in the processing of the part. While less aggressive medias such as Plastic Media or Synthetic Media are typically used with softer metals like aluminum, the results above show a comparison of a Plastic Media versus a more aggressive Ceramic Media.

The picture shows the machined part on the far left followed by a part tumbled with a general purpose Plastic Triangle (middle) with a different part tumbled with a Ceramic Triangle on the far right. Both tumbled parts were vibratory tumbled for 1 hour with the same Kramco 1030 mild acid compound.

The machined part shows heavy burrs and machining marks on the surface. Both media types removed the machine marks and the burrs on the edges. The differences show up when looking more closely at the 'roughness' of the surface finish and the amount of edge rounding after the 1 hour cycle time.

The Plastic Media tumbled part shows slight edge rounding and a matte but uniform surface finish. This is a good finish for anodizing the aluminum part to a matte, smooth finish. The Ceramic Media tumbled part has noticeably more edge rounding and a more tumbled, 'rough-looking' surface finish. This finish is better for accepting paint or powder coating.

Powder Coat Stripping

Powder coating is used in applications where a tougher finish is required than a traditional liquid paint. The free-flowing, dry powder is typically applied electrostatically and then heat cured to form the bond. Powder coatings are very difficult to remove from the sub-surface as they are often thicker and more aggressively bonded to the surface than more traditional coatings.

Removing powder coating from a surface can be a challenging process. In addition to the thickness of the coating, the bond between the powder and the metal often requires more energy to break than the force needed to etch or potentially damage the sub-surface.

This powder coated punched hole wire mesh was stripped (right side) using an abrasive blasting process with 60 mesh Aluminum Oxide Grit. A larger grit size was also tested (which did strip the coating more quickly) but the metal surface became too heavily etched. Less aggressive media such as Glass Bead and Plastic Abrasive Media were unable to efficiently remove the coating.

Cleaning Welding Discoloration

Welding steel often creates heat discoloration and welding burns. Prior to finishing many parts with processes such as powder coating, painting, clear coats or simple final assembly, the removal of the discoloration and preparation of the surface is necessary.



Elements were welded onto this steel tube prior to powder coating. In addition to the discoloration (blue streak seen on the left side), this part started to rust in storage. The powder coating process specified that the part be clean and smooth.

The right side of the part was blasted with Medium Glass Bead to remove the oxidation, discoloration and provide a smooth, lightly peened surface finish.

Powder Coat Removal

Summarized from the ShopTalk Forum:

Question: I race ATV's and each winter tear them down for rebuilding. What would be the best blast media to use to remove the old powder coat? I don't want to etch the frame too much as some of the parts are aluminum. I am trying to use a material that can be re-used so it's cost effective. A media that is not too dusty would be preferred since I am blasting indoors. I will be powder coating over the frames so what grit would leave a proper profile?

Response: Powder coating can be difficult to remove so a relatively aggressive media is needed. A 60 Mesh Aluminum Oxide Grit should strip the coating and leave the aluminum metal with a light etch for re-coating. Aluminum Oxide can be re-used up to 30 times.