Arcshield ZN 340 Inorganic Zinc Silicate Primer
A solvent-borne ethyl silicate zinc primer that cures by reaction with atmospheric moisture to form a hard, inorganic zinc-bearing film. It has higher heat and solvent resistance than an organic zinc primer and is specified for CX systems, as a fabrication holding primer and beneath high-temperature finishes.
Grade Arcshield ZN 340 | Range Protective and Marine Coatings | Technology Solvent-borne ethyl silicate binder with zinc dust, moisture curing
Technical Data Sheet
Arcshield ZN 340
Issue 2026.09
1. Product description
A solvent-borne ethyl silicate primer that cures by reaction with atmospheric moisture to form a hard, inorganic zinc-bearing matrix. It carries higher heat resistance and higher solvent resistance than the organic grade, and is specified under systems for CX exposure, as a holding primer for fabrication, and beneath high-temperature finishes where an organic primer would degrade. Cure depends on ambient humidity, and film thickness control is critical because over-application causes mud-cracking and delamination.
2. Features
- Inorganic zinc silicate film giving galvanic protection to blast-cleaned steel
- Higher heat and solvent resistance than an organic zinc-rich primer
- Suitable beneath high-temperature finishes where an organic primer would degrade
- Moisture-curing binder, with cure confirmed by solvent rub before overcoating
3. Recommended uses
Primer for steelwork in CX and offshore exposure, holding primer for fabricated steel, and base coat beneath silicone and other high-temperature finishes on stacks and hot pipework.
Substrates. Abrasive blast cleaned carbon steel to Sa 2½ or Sa 3 with a measured profile. It requires a clean, dry, salt-free surface and is not suitable over hand-prepared steel or over aged coatings.
4. Typical properties
| Property | Typical value | Method |
|---|---|---|
| Technology | Solvent-borne ethyl silicate binder with zinc dust, moisture curing | Formulation |
| Appearance | Grey, matt inorganic film | Visual, supplier protocol |
| Zinc dust content of the dry film | 80 per cent or more by mass of the non-volatile portion where the specification calls for a zinc-rich primer to ISO 12944-5 | Content declared in the product data, zinc dust pigment to the classes of ISO 3549 |
| Volume solids | Typically 55 to 70 per cent | ISO 3233-1 |
| Dry film thickness per coat | Typically 50 to 75 µm in a single pass; over-application beyond the stated maximum causes mud-cracking and delamination | ISO 2808, ISO 19840 for blast-cleaned steel |
| Cure | By reaction with atmospheric moisture, with relative humidity held at around 50 per cent or above during cure | ASTM D4752 solvent rub, rated to the acceptance level in the specification |
| Pull-off adhesion | Typically 3 to 6 MPa on blast-cleaned steel | ISO 4624, ASTM D4541 |
| Cyclic ageing, offshore and CX systems | 4200 h test cycle where the complete system is offered to the offshore regime | ISO 12944-9 |
| Dry heat resistance | Suitable beneath high-temperature finishes; the dry heat limit is stated for the complete system | ASTM D2485 |
Typical values, not a specification. Values for each batch are given on its Certificate of Analysis.
5. Application
| Parameter | Guidance |
|---|---|
| Method | Airless spray with continuous agitation, applied in a single pass to the specified thickness rather than built up wet on wet. |
| Surface preparation | Abrasive blast cleaning to Sa 2½ or Sa 3 (ISO 8501-1) with a measured, sharp angular grit profile, typically 50 to 85 µm Rz (ISO 8503-2, ASTM D4417). The surface must be clean, dry and free of soluble salts to the limit in the specification (ISO 8502-6 with ISO 8502-9). Not for hand-prepared steel or aged coatings. |
| Thinning | Thinner as stated on the product data, used only to suit the application conditions. |
| Applied film thickness | Typically 50 to 75 µm dry in one pass, verified to ISO 19840, without exceeding the stated maximum. |
| Cure conditions | Steel temperature at least 3 °C above dew point. Relative humidity held at around 50 per cent or above during cure, because cure depends on atmospheric moisture. |
| Overcoating | Overcoat only after cure is confirmed by solvent rub to ASTM D4752. Apply a mist coat or a tie coat before a high-build epoxy to prevent bubbling over the porous zinc silicate film. |
Process. Airless spray with continuous agitation, applied in a single pass to the specified thickness rather than built up wet on wet. Cure needs atmospheric moisture, so relative humidity is held at or above roughly 50 % during cure and the film is checked by solvent rub to ASTM D4752 before overcoating. A mist coat or a tie coat is used to prevent bubbling when a high-build epoxy is applied over a porous zinc silicate film.
6. Storage and handling
Store in the original, tightly closed containers in a dry, covered store, typically between 5 and 35 °C and out of direct sunlight, because the binder reacts with moisture. Shelf life is stated on the label and the Certificate of Analysis. Handle and use the product in line with its Safety Data Sheet.
7. Safety and regulatory information
Read the Safety Data Sheet before use. Safety Data Sheets and regulatory declarations are issued by our technical centre against the product and batch supplied, so they are sent on request rather than published. Request a Safety Data Sheet or declaration.
This Technical Data Sheet is published for on-screen reference. The information is given in good faith from laboratory and application experience and describes typical values; it is not a specification and does not replace a trial on your own substrate and line. Arctic Materials may revise this sheet without notice. Issue 2026.09.
Technical Data Sheets on this site are for on-screen viewing. For a controlled copy, write to tech@arcticmaterials.com.
Other grades in this range
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