Metal and wooden parts of a manual post-hole auger will be coated to lengthen the lifespan of the tool.
Powder coating
Powder coatings are made of plastic and are used on metal parts to protect the surface of the metal from light damage and water, which can result in rusting of the steel.
The powder is sprayed onto the part. It sticks due to static electricity. After heat treatment, the powder forms a hard, thick coat, which is less likely to chip than paint.
Powder coatings are better at retaining the shape of the cutting edge than paint is.
Paint
Paint creates a protective layer over metal or wood. The layer keeps water away from the materials, avoiding corrosion and rot.
Paint is only a thin layer and can chip easily. It needs maintenance more regularly than other coatings. All chips need repainting to complete the barrier again.
Wood preservative
Wood preservatives protect wood from rotting by preventing fungi, bacteria and insects from eating the wood.
They also provide a barrier against water which can damage wood, too.
