PPG SigmaCover 256 – High-Build Zinc Phosphate Epoxy Primer

PPG SigmaCover 256 is a two-component, high-build, polyamide-cured zinc phosphate epoxy primer designed for steel and concrete structures exposed to industrial and marine environments. This versatile coating provides exceptional corrosion protection, long-term durability, and superior adhesion, making it an ideal primer or buildcoat in protective coating systems for harsh atmospheric conditions.

SigmaCover 256 delivers excellent rust-prevention in industrial and coastal atmospheres, withstanding weathering and maintaining flexibility over time. It can be recoated with a variety of two-component or conventional coatings, even after extended exposure, and performs well in both new construction and maintenance projects. Its reliable curing down to -10°C (14°F) allows for year-round application without compromising performance.

Key Features:

• Two-component, high-build zinc phosphate epoxy primer

• Excellent corrosion and rust protection for steel and concrete

• Suitable for industrial and marine environments

• Recoatable after long weathering periods

• Cures at low temperatures (down to -10°C)

• Excellent adhesion to steel, galvanised steel & aged epoxy coatings

• Flexible and durable finish

• Easy application by airless spray or brush

• Can serve as primer/finish for dry internal areas

Surface Preparation

Substrate conditions
• Steel; blast cleaned to ISO-Sa2½, blasting profile 40 – 70 µm (1.6 – 2.8 mils)
• Shop primed steel; pretreated to SPSS-Pt3 / SSPC-SP3
• Galvanized steel must be sweep blasted until an even flat appearance (only for internal dry exposure conditions)
• Aged suitable coating must be dry and free from any contamination
Substrate temperature
• Substrate temperature during application and curing down to -10°C (14°F) is acceptable; provided the substrate is free
from ice and dry
• Substrate temperature during application should be at least 3°C (5°F) above dew point
• Relative humidity during application and curing should not exceed 95%

Technical Data

Pot life
8 hours at 20°C (68°F)
Note: See ADDITIONAL DATA – Pot life

DFT Theoretical spreading rate
75 µm (3.0 mils) 8.4 m²/l (337 ft²/US gal)
100 µm (4.0 mils) 6.3 m²/l (253 ft²/US gal)
150 µm (6.0 mils) 4.2 m²/l (168 ft²/US gal)

Directions for Use

Mixing ratio by volume: base to hardener 82:18
• The temperature of the mixed base and hardener should preferably be above 15°C (59°F), otherwise extra thinner may be
required to obtain application viscosity
• Adding too much thinner results in reduced sag resistance and slower cure
• Thinner should be added after mixing the components

Air spray
Recommended thinner
THINNER 91-92
Volume of thinner
10 - 15%, depending on required thickness and application conditions
Nozzle orifice
1.5 – 3.0 mm (approx. 0.060 – 0.110 in)
Nozzle pressure
0.3 - 0.4 MPa (approx. 3 - 4 bar; 44 - 58 p.s.i.)

Airless spray
Recommended thinner
THINNER 91-92
Volume of thinner
5 - 10%, depending on required thickness and application conditions
Nozzle orifice
Approx. 0.48 mm (0.019 in)
Nozzle pressure
15.0 MPa (approx. 150 bar; 2176 p.s.i.)

Brush/roller
Recommended thinner
THINNER 91-92
Volume of thinner
0 – 5%

Cleaning solvent
THINNER 90-53

Data Sheets

SigmaCover 256 TDS

SigmaCover 256 Base MSDS

SigmaCover 256 Hardener MSDS