Learning Center Substrate Info
Aluminum
Powder Coating for Aluminum Substrate Applications
Powder Coating is the fastest growing finishing technology for architectural aluminum. Able to meet & exceed AAMA, GSB and Qualicoat specifications, provided it is pretreated with a chrome or non chrome conversion coating as outlined in the above mentioned specifications. For highly corrosive environments, 4000hrs of salt spray resistance according to ASTM-B117 are required of the pretreatment system in place, to ensure longevity.
Steel / Iron
Powder Coating for Steel Substrate Applications
Protecting Steel against the environment is of vital importance as corrosion may affect the structural properties. The prefered method of pretreating Steel prior to painting is to Sandblast to SA2.5 (near white metal) and utilizing an epoxy based primer either with or without zinc as a sacrificial element. An alternative is to utilize an Iron or Zinc Phosphate pretreatment. A very popular standard for specifying corrosion protection on Structural Steel is ISO 12944. This Standard was developed to assist engineers, architects and corrosion experts in specifying the proper paint system for corrosive environments.
Cast Aluminum and Cast Steel
Powder Coating for Steel & Aluminum Casting Substrate Applications
In porous substrates, such as cast aluminum & steel, out-gassing of air trapped deep in the material will occur at the curing stage of the powder coating process. Since powder coatings form a continuous surface, this process of out-gassing will cause surface disturbances in the cured finish, in the form of holes similar to pinholes. Eliminating this process of out gassing can be achieved by the casting manufacturer via utilizing an impregnator to fill said holes. The applicator can utilize out gassing forgiving primers and/or topcoats to reduce or eliminate the above mentioned surface disturbances as well.
Galvanized Steel
Powder Coating for Galvanized Steel Substrate Applications
When dealing with Galvanized Steel, two areas need to be addressed in order to achieve a coating without defects as well as proper adhesion.
- Out gassing, due to the Silica content, galvanized steel creates the same surface disturbances as cast aluminum & steel from out gassing. This can be dealt with by utilizing out gassing forgiving primers and/or topcoats.
- Adhesion of powder coatings to galvanized steel is achieved by eliminating the passivating film on the surface. It is essential that galvanized items not be quenched after the galvanizing process in order to leave the surface reactive. Due to this reactivity it is also essential the material is coated within 24-48 hours after galvanization to avoid or reduce oxidization that could again lead to adhesion issues.Additionally, it is recommended to sweep blast or run the parts through a chromate pretreatment to improve adhesion.
Stainless Steel
Powder Coating for Stainless Steel Substrate Applications
Stainless Steel’s smooth surface has to be prepared in order to provide a proper surface for the powder coat to adhere to. This can be achieved via mechanical means such as sanding, brushing or blasting the surface. Due to the great number of different types and qualities of stainless steel it is always recommended to perform a cross hatch adhesion test prior to finishing an entire lot of material.