HIGH TEMPERATURE POWDER APPLICATIONS

High performance coatings have many properties that are different from standard epoxy and polyester powder coatings. Extra attention to proper pretreatment, application and curing is required to ensure maximum performance.

These coatings are generally appropriate for steel, cast aluminum and type 1 aluminized steel. Since various grades of substrates are available each may have its own temperature limits. For outdoor use aluminum or aluminized steel is recommended.

Pre-treatment:

High temperature coatings require cleaner substrates to create good adhesion. Proper pretreatment is essential.

Chemical pretreatment:

Use a alkaline cleaner under high pressure followed by a thorough rinse with deionized water. Force dry and coat as soon as possible to avoid excessive rust. Do not use any pretreatment method that will leave a coating or sealer on the surface.

DO NOT USE PHOSPHATE ON STEEL SUBSTRATES AS THE PHOSPHATE LAYER WILL FAIL AT HIGH TEMPERATURE.

Mechanical pretreatment:

Clean abrasive media blast is highly recommended. This will provide a clean surface as well as good profile for optimum powder adhesion.
After blasting remove dust with air and do not hand wipe with any type of solution after blasting.

Fluidization:

This type of material is highly electrostatic-ally active. Vibration during transit may cause small, soft electrostatic agglomerations of powder sometimes described as lumpy. This is normal and easily corrected by conditioning the powder prior to use.

Filter the powder through clean grounded wire mesh, such as window screen. Then if using a fluidizing setup, fluidize the powder for several minutes prior to spraying.
If the lumps are hard then most likely the powder has gotten to hot in transit or during storage and has sintered. It is highly recommended to use a fluidizing hopper while applying this powder. Vibratory box feeders may cause the powder to compact in the box and be difficult to spray.

Application:

Use electrostatic application and apply to room temperature substrate (no higher than 75 degrees). Since silicone resins have a lower melting point they will become tacky at well under 100 degrees.

Thickness should be between 1.0 to 3.0 mils. Applying to thick can cause out gassing and adhesion problems.
Pre heating the substrate will make it very difficult to control the mil thickness.
Shooting at 50KV has shown excellent results with controlling mil thickness.

Curing:

Silicone powders generally require more energy to cure. Without a full cure the coating will have less flexibility and be prone to cracking , chipping and corrosion.

Carefully follow the minimum cure cycle recommended. Achieving part metal temperature is crucial. Some times you can achieve better results with increased time and temperature. Since these are high temp powders there is no chance of over baking them at 450/F.

Cleanup:

Use cold water only, warm water will only melt the powder and make it more difficult to clean.

Storage:

Silicone powders are more sensitive to heat and humidity than standard powders. They should be stored at 75/F or lower.