Masking Tapes for Anodization and Powder Coating

Why is masking an essential part of these processes?

While the effects of anodization or powder coating are of benefit to the end user, there are parts of the component being treated that may need to be masked to prevent the coating being applied.

• Electrical contact is required – anodization works as an electrical insulator.
  
• Prior to assembly –anodization adds a layer, and so can change the dimensions of components.
  
• Prior to bonding – it is not easy to bond to a powder coated or anodized surface.
  
• Prior to welding – it is difficult to weld to a powder coated surface.
  
• Aesthetic reasons – where colour is added to the process, some areas may need to be masked.

Anodization generally occurs on aluminium substrates, but can also be done on magnesium and titanium. Anodization is an electrochemical conversion process that can increase the hardness of the substrate, provide electrical insulation, resist corrosion and add colour as a decorative feature.

There are three common types of anodization processes:

• Type I – Chromic – using chromic acid in a very thin coating, primarily in the aerospace industry.
  
• Type II – Regular – using sulphuric acid at room temperature, this relatively inexpensive process provides a harder finish than chromic anodization.
  
• Type III – Hardcoat – again using sulphuric acid but at lower temperatures and in thicker coatings to provide extreme durability and corrosion resistance.

Powder Coating

Powder coating is a finishing process that is applied as a dry powder, melted, and then hardened into an even coating. This provides a functional and decorative finish not available from conventional liquid coating processes, which is safer for the environment and durable in the toughest environments.

There are a number of different powder types available for use in this process, all of which have their own benefits and typical applications. These include epoxy, polyester and urethane.

Why is masking an essential part of these processes?

While the effects of anodization or powder coating are of benefit to the end user, there are parts of the component being treated that may need to be masked to prevent the coating being applied.

• Electrical contact is required – anodization works as an electrical insulator.
  
• Prior to assembly – powder coating adds a layer, and so can change the dimensions of components.
  
• Prior to bonding – it is not easy to bond to a powder coated or anodized surface.
  
• Prior to welding – it is difficult to weld to a powder coated surface.
  
• Aesthetic reasons – where colour is added to the process, some areas may need to be masked