PPG SigmaZinc 160 is a two-component, moisture-curing inorganic zinc (ethyl) silicate anti-corrosive primer for structural steel. This low-temperature curing coating is suitable as a system primer in various paint systems based on unsaponifiable binders.

Top Features & Benefits

• Two-component product consisting of clear binder and zinc paste
• Galvanic action eliminates sub-film corrosion
• Can withstand substrate temperatures from –90°C (–130°F) up to 400°C (750°F), under normal atmospheric exposure conditions
• When suitably topcoated provides excellent corrosion protection for steel substrates up to 540°C (1000°F)
• Good impact and abrasion resistance
• Complies with SSPC-Paint 20

Preparation & Application

Recommended Substrate Conditions and Temperature

Immersion Exposure

• Steel; blast cleaned to ISO-Sa2½, blasting profile 40 – 70 µm (1.6 – 2.8 mils)
• Steel with approved zinc silicate shop primer; sweep blasted to SPSS-Ss welds. rusty and damaged areas blast cleaned to ISO-Sa2½

Atmospheric Exposure Conditions

• Steel; blast cleaned to ISO-Sa2½, blasting profile 40 – 70 µm (1.6 – 2.8 mils)
• Steel with approved zinc silicate shop primer; pre-treated to SPSS-Pt3

Substrate Temperature and Application Conditions

• Substrate temperature during application and curing down to -5°C (23°F) is acceptable; provided the substrate is free from ice and dry
• Substrate temperature during application up to 50°C (122°F) is acceptable
• Substrate temperature during application and curing should be at least 3°C (5°F) above dew point
• Relative humidity during curing should be above 50%

Instructions for Use

Mixing ratio by volume: binder to paste 35.5:64.5. Use a mechanical mixer. Stir the paste thoroughly before adding the binder. Add the binder gradually to the paste. Stir thoroughly until homogeneous

Do not mix in reverse order.

Strain the mixture through a 30–60 mesh screen. Agitate continuously during application (low speed). The use of a dedicated pump with a constant agitation for a zinc silicate coating is recommended

Note:
At application temperature above 30°C (86°F) addition of max 10% by volume of THINNER 90-53 may be necessary.

Pot Life

12 hours at 20°C (68°F)

Air Spray

Recommended thinner: PPG Thinner 90-53

Volume of thinner: 0 - 10%, depending on required thickness and application conditions

Nozzle orifice: 2.0 mm (approx. 0.079 in)

Nozzle pressure: 0.3 MPa (approx. 3 Bar; 44 p.s.i.)

Airless Spray

Recommended thinner: PPG Thinner 90-53

Volume of thinner: 0 - 10%, depending on required thickness and application conditions

Nozzle orifice: Approx. 0.48 – 0.64 mm (0.019 – 0.025 in)

Nozzle pressure: 15.0 MPa (approx. 150 bar; 2176 p.s.i.)

Note:
A dedicated pump for a zinc silicate coating with constant agitation must be used.

Brush/Roller

Only for touch-up and spot repair.

Recommended thinner: PPG Thinner 90-53

Volume of thinner: 5 – 15%

Note:
Apply a visible wet coat with a max. dft of 25 µm (1.0 mils)|same for subsequent coats in order to obtain the required dft.

Cleaning Solvent

PPG Thinner 90-53

Upgrading

This is only valid for spray application. If the DFT is below specification and an extra coat of SIGMAZINC 160 has to be applied, SIGMAZINC 160 should be thinned down with 25 – 50% THINNER 90-53, in order to obtain a visible wet coat that remains wet for some time.

Safety Precautions

1. For paint and recommended thinners see INFORMATION SHEETS 1430, 1431 and relevant Material Safety Data Sheets.
2. 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.

Product Data

Notes:
Highly pigmented zinc silicate primers produce dry films with void spaces in between the particles. Maximum interval is only unlimited when the surface is free from any contamination. A relative humidity below 50% requires a much longer overcoating time. Before entering service or overcoating, a sufficient degree of cure should be obtained. Before overcoating with topcoats, SIGMAZINC 160 should always be visibly dry and checked on sufficient curing.

If part of a coating system and in order to avoid possible popping effects (pinholes) SIGMAZINC 160 should be sealed with approved coatings.

When curing conditions are unfavourable or when reduced overcoat times are desired, curing can be accelerated 4 hours after application by:

1. Wetting or soaking with water, keeping the surface wet for the next 2 hours, followed by drying.
2. Wetting or soaking with a 0.5% ammonia solution, followed by drying.

For measuring of the curing, the MEK rub test according to ASTM 4752 is a suitable method: after 50 double rubs with a cloth soaked in MEK (or alternatively THINNER 90-53) no dissolving of the coating should be observed.

References

• Safety Indicators (information sheet 1430)
• Safety in Confined Space and Health Safety, Explosion Hazard - Toxic Hazard (information sheet 1431)