PPG SigmaTherm 540 is a one-component, heat-resistant, moisture-curing silicone aluminum coating for protecting steel surfaces in internal and external applications. Complies with NACE SP0198 for austenitic stainless steels and carbon steels under thermal insulation.

Principal Characteristics

• Dry heat resistance up to 600°C (1112°F)
• No heat cure necessary between coats
• Excellent resistance against weathering
• Also suitable on top of zinc silicate primer
• A minimum drying time of 3 days at 20°C (68°F) should be allowed before exposure to heat

Product Data

Two-component, high-build, heat-resistant epoxy phenol novolac coating.

Epoxy coatings will chalk and fade upon exposure to sunlight, elevated temperatures, or chemical exposure. Discolouration and normal chalking does not impact performance. Light colours will darken over time. Some batch-to-batch variation in colour is to be expected. Colour matches are approximate.

Notes:

• Refer below for more details on spreading rate and film thickness, overcoating intervals and curing times

Surface Preparation

Recommended Substrate Conditions and Temperatures

• Steel; blast cleaned to ISO Sa 2½ or SSPC-SP-10, blasting profile 25 – 50 µm (1.0 – 2.0 mils)
• Suitable coating (zinc silicate primer) must be dry, free from any contamination and zinc salts
• Stainless steel; degreased and sweep blast (SSPC SP-16) cleaned to roughness of 40 – 70 µm (1.5 – 2.8 mils) with nonferrous abrasive

Note:

• The maximum continuous dry heat temperature when power tool treated surface (ISO-St3) is 400°C

Substrate Temperature & Application Conditions

• Substrate temperature during application and curing should be at least 3°C (5°F) above dew point

System Specification

Suitable Primers :

• PPG Ethyl Silicate Zinc Primers

Do not use HI-TEMP 1027 or 222G as primer.

Direct to stainless steel with suitable surface treatment.

Application

Instructions for Use

• Power agitate to uniform consistency
• Application with airless equipment is possible, but be careful not to apply more than specified thickness
• When applying more than one coat, it is recommended that the total dry film thickness of SigmaTherm 540 does not exceed 80 µm (3.1 mils)

Air Spray

Recommended thinner

• No thinner should be added

Nozzle orifice

• 1.5 – 2.0 mm (approx. 0.060 – 0.079 in)

Nozzle pressure

• 0.3 - 0.4 MPa (approx. 3 - 4 bar; 44 - 58 p.s.i.)

Brush/roller

• For Roller application the best results will be obtained by using fine foam type rollers

Cleaning Solvent

• Thinner 21-06

Spreading Rate and Film Thickness

Overcoating interval for DFT up to 25 µm (1.0 mils)

Notes:

• Surface should be dry and free from any contamination

Curing time for DFT up to 25 µm (1.0 mils)

Notes:

• Adequate ventilation must be maintained during application and curing (please refer to information sheets information sheet 1433 and
• Directives for Ventilation Practice (information sheet 1434)

Safety Precautions

• For paint and recommended thinners, see information sheets information sheet 1430, information sheet 1431 and the relevant Material Safety Data Sheets in the attachments section above
• This is a solvent-borne paint and care should be taken to avoid inhalation of spray mist or vapor, as well as contact between the wet paint and exposed skin or eyes

References

• Conversion Tables (information sheet 1410)
• Explanation to product data sheets (information sheet 1411)
• Safety Indicators (information sheet 1430)
• Safety in Confined Space and Health Safety, Explosion Hazard - Toxic Hazard (information sheet 1431)
• Cleaning of Steel and Removal of Rust (information sheet 1490)
• Specification for Mineral Abrasives (information sheet 1491)
• Relative humidity - Substrate Temperature - Air Temperature (information sheet 1650)