Pretreatment Standards

The pre-treatment process must be capable of meeting the performance outputs as described in AS3715 Compliance to appropriate process parameters is essential in ensuring compliance to etch, conversion coating weights (time/concentration) and conductivity of the final rinse.

Etch

The etch process is a very important stage of pre-treatment and close consultation with your pre-treatment supplier is strongly recommended to ensure optimum adhesion & corrosion resistance is obtained. As an approximate guide:

• An etch rate of >1gm/m2 , is recommended for Surreal Effects projects but etch rate advice from pre-treatment suppliers should be taken into consideration.

Conversion Coatings

This is the next pre-treatment process for aluminium to ensure that it is suitably prepared for coating.

• Chrome conversion weights must be a minimum of 431mg/m².
• Chrome-free conversion weights - refer to your pre-treatment supplier as currently no standards address chrome-free.
• Chrome-free conversion coatings should be applied and maintained in accordance with the manufacturer’s instructions.
• When changing from chrome to chrome-free your accreditation will require reapplication immediately. Warranty applications through this period will need to be monitored, tested and approved individually.

Final Rinse

Final rinse is to ensure optimum surface preparation prior to coating.

• Final rinse water run-off from the extrusion is recommended to have a conductivity of less than 80 micro Siemens/cm.
• Pre-treated aluminium must be powder coated within the time specified by the pre-treatment supplier - this is generally within 16 to 48 hours.
• The entire area of the aluminium shall be properly pre-treated, appropriate spacing devices should be used.

Handling

Care should be taken with handling to ensure health and safety measures are met and that the substrate is not contaminated.

• Pre-treated sections must never be handled with bare hands. Clean and lint free cotton gloves must be worn at all times when handling pre-treated sections.

Dry Off Oven (if applicable)

If your site uses a dry off oven to assist in the pre-treatment process, consult your pre-treatment supplier for advice, but generally;

• < 75° C for chrome pre-treatment,
• < 120° C for chrome-free pre-treatment.
• Applicators must be able to demonstrate compliance with this specification.

Steel substrates shall be prepared as follows:

1. Wash and degrease all surfaces to be coated in accordance with AS1627.1 with a free-rinsing, neutral/alkaline detergent, in strict accordance with the manufacturer’s written instructions and all safety warnings.

2. Wash with fresh potable water and ensure that all soluble salts are removed. Testing if required can be done in accordance with AS 3894.6 for the determination of residual contaminants.

3. Grind all sharp edges with a power tool to a minimum radius of 2mm.

4. Hand or power tool clean welds to AS1627.2 to remove roughness. Remove filings, preferably by vacuum.

5. Abrasive blast clean all steel surfaces to be powder coated in accordance with AS 1627.4 to the visual cleanliness standard of SA 2.5. Use a medium that will generate a surface profile of 35 to 65 microns. In situations where it is not possible to prepare your item on all surfaces as described above, for long term protection against corrosion it is strongly recommended whenever possible, that an alternative substrate such as aluminium be considered. Failure to suitably prepare your steel substrate may void your Steel Shield™ warranty.

6. The steel must be coated within 4 hours of blasting and stored in an area which is clean and dry. Dulux Accredited Powder Coaters must comply with the metal pre-treatment guidelines set out in the Accredited Steel Shield™ Manual.

Application Method

Electrostatic Spray

Metal Temperature:

210° : 4 mins minimum

200° : 5 mins minimum

180° : 8 mins minimum

Due to the structure of the finishes, the film build is critical to both the aesthetic and functional characteristics of the film. Refer to the Surreal Effects Product Data sheet for further information.