Intertherm 50 Silicone Heat-resistant Coating is a heat-resistant coating. For protection of steel from corrosion in open-flame chimneys, ordinary chimneys, exhaust units, ventilation equipment and piping areas at temperatures up to 540°C (1004°F). The moisture-cure crosslinking process permits application of multiple coats without heat curing. In corrosive environments, direct application of black Intertherm 50 over zinc silicate primer will cause a significant colour change from black to grey due to the "salting-out effect" of the primer beneath. Parameters on this page: theoretical spreading rate 18 m²/L; number of components: one-component.
Source of parameters: AKZONOBEL manufacturer's Technical Data Sheet (TDS) "Intertherm 50 Silicone Heat-resistant Coating"; values such as spreading rate are converted from TDS parameters and are for selection reference only.
The above content is compiled from the manufacturer's datasheet and this site's parameter tables. For selection, coating systems and lead times, pleaseContact Usfor confirmation.
This page carries the full TDS for this product, translated from the manufacturer's original document. No file download is needed; for an original-language copy, send an enquiry.
| Volume Solids | 45% |
|---|---|
| Dry Film Thickness | — |
| Theoretical Spreading Rate | 18 m²/L |
| VOC | 4.13 lb/gal (495 g/L) US Environmental Protection Agency Method 24 509… |
| Density / Specific Gravity | 1.13 kg/L (9.4 lb/gal) |
| Number of Components | One-component |
| Flash Point | 25°C (77°F) |
| Thinner | Do not exceed the thinning limits of local environmental regulations |
| Mixing Ratio | N/A |
For more Q&A on selection, application, acceptance and defect diagnosis, seeFAQsection.
This is a one-component high-temperature coating containing a moisture-cure silicone binder.
The moisture-cure crosslinking process permits application of multiple coats without heat curing. It withstands temperatures up to 540°C (1004°F).
For protection of steel from corrosion in open-flame chimneys, ordinary chimneys, exhaust units, ventilation equipment and piping areas at temperatures up to 540°C (1004°F).
If stronger anticorrosive protection is required, apply one coat of zinc silicate primer (for example, Interzinc 22) before applying this product.
| Colour | Aluminium colour, Black INTERTHERM 50 |
|---|---|
| Gloss | N/A |
| Volume Solids | 45% |
| Typical thickness | 25 µm (1 mil) dry film equivalent to 56 µm (2.2 mil) wet film |
| Theoretical Spreading Rate | At 25 µm dry film thickness and the stated volume solids, 18 m²/L; at 1 mil dry film thickness and the stated volume solids, 722 ft²/US gal. |
| Practical Spreading Rate | Allowing for a suitable loss factor |
| Application Methods | Air spray, brush, roller. Drying time; recommended topcoat recoat interval |
| Temperature | Surface Dry | Hard Dry | Minimum | Maximum |
| 5°C (41°F) | 90 min | 5 h | 24 h | Unlimited¹ |
| 15°C (59°F) | 60 min | 3 h | 16 h | Unlimited¹ |
| 25°C (77°F) | 30 min | 2 h | 12 h | Unlimited¹ |
| 40°C (104°F) | 15 min | 1 h | 6 h | Unlimited¹ |
¹ See Definitions and Abbreviations from the International Paint Protective Coatings division.
| Flash point (typical) | 25°C (77°F) |
|---|---|
| Product weight | 1.13 kg/L (9.4 lb/gal) |
| Volatile Organic Compounds | 4.13 lb/gal (495 g/L) US Environmental Protection Agency Method 24 509 g/kg European Community Solvent Emissions Directive content (EU Council Directive 2010/75/EU) coating hazard GB 30981.2-S-Pb≤1000-NC compliant with GB 30981.2-2025. For more detailed information, see the section on "Product Characteristics". |
All surfaces to be coated must be clean, dry and free of contaminants. Before application, all surfaces must be assessed and prepared in accordance with ISO 8504:2000.
Oil and grease must be removed in accordance with the SSPC-SP1 solvent cleaning standard.
Abrasive Blast Cleaning: steel surfaces shall be blast-cleaned to Sa2½ (ISO 8501-1:2007) or SSPC-SP6. If oxidation occurs between abrasive blast cleaning and application of Intertherm 50, the surface shall be re-blasted to the specified visual standard.
Surface defects exposed by blast cleaning must be ground, filled or treated by a suitable method.
Recommended surface profile is 25–50 µm (1–2 mil).
Hand or power tool preparation: all coatings present on the surface must be removed before application of Intertherm 50.
Hand or power tool cleaning to St3 (ISO 8501-1:2007) or SSPC SP3 minimum standard.
Note: all mill scale shall be removed; areas not suitably treated by chipping or needle gun shall be spot-blasted to Sa2 (ISO 8501-1:2007) or SSPC SP6 as a minimum. This generally applies to grade C or D rusting.
Pre-primed surfaces: Intertherm 50 is suitable for application to steel components with newly applied zinc silicate shop primer.
If the zinc dust shop primer shows large-scale scattered breakdown or heavy zinc salts, the entire area must be fully sweep blasted.
Not suitable for recoating other types of shop primer; remove them completely by abrasive blasting.
Welds and damaged areas must be blast cleaned to Sa 2½ (ISO 8501-1:2007) or SSPC-SP6.
Metal spraying and aluminium spraying: use fresh, clean, moisture-free gas that does not contaminate the steel surface.
| Mixing | This product is a single-component coating; stir thoroughly with a power mixer before each use |
|---|---|
| Mixing ratio | N/A |
| Suitable for airless spray | Not recommended |
| Air Spray | Recommended | Spray gun | DeVilbiss MBC or JGA |
| Air nozzle | 704 or 765 | ||
| (with pressure pot) | Nozzle | E | |
| Air spray (conventional) | Recommended | Use suitable dedicated equipment. | |
| Brush | Applicable — for small-area repair only | Typical thickness 15–20 µm (0.6–0.8 mil) | |
| Roller application | Applicable — for small-area repair only | Typical thickness 15–20 µm (0.6–0.8 mil) | |
| Thinner | International GTA007 | Do not exceed the thinning limits of local environmental regulations |
| Cleaner | Use a cleaning solvent that complies with local regulations. Consult the local representative for specific recommendations. |
|---|---|
| Interruption of work | Material retention in spray hoses, spray guns or spray equipment is not permitted. Thoroughly flush all equipment with International brand cleaner. |
After storage in partially filled cans, surface skinning or viscosity increase may occur.
| Cleaning | All equipment should be cleaned immediately after use with International thinner. Flushing spray equipment periodically during daily work is good practice. Cleaning frequency depends on the volume sprayed, temperature, spraying time, including delays, and other factors. |
|---|
All surplus paint and empty containers must be disposed of in accordance with the relevant local laws/regulations.
Intertherm 50 is moisture-curing and, unlike conventional silicone coatings, does not generate water vapour during heat curing. Therefore, it can be applied at 25 µm (1 mil) instead of the conventional 15 µm (0.6 mil).
Under heating, the maximum thickness of a single coat that can be applied without blistering is 40 µm (1.6 mil).
Three coats can be applied at 25 µm (1 mil) per coat, with no heating required between coats. Where zinc silicate primer cannot be used, this method provides maximum protection.
Two colour variants are available: aluminium and black. As aluminium-containing variants offer better performance, use of aluminium-coloured Intertherm 50 is recommended wherever possible. The black variant is for special application/requirements only. Consult International Paint Industrial Coatings for further information.
The aluminium-pigmented variant of Intertherm 50 is suitable for protecting blast-cleaned steel structures operating continuously at drying temperatures up to 540°C (1004°F). However, the maximum service temperature on hand-prepared substrates is 400°C (752°F).
The black variant of Intertherm 50 is suitable for protecting blast-cleaned steel structures operating continuously at drying temperatures up to 400°C (752°F). However, the maximum service temperature on hand-prepared substrates is 300°C (572°F).
When applying a heat-resistant coating over an inorganic zinc primer, the product shall be applied strictly to the film thickness specified in the coating system, since excessive film thickness will cause blistering. Before applying the heat-resistant coating, follow the curing instructions in the product data sheet to ensure the inorganic zinc primer is fully cured.
When a zinc silicate primer is used to achieve optimum anticorrosive performance, a dry film thickness of 50 µm (2 mil) is recommended for the zinc silicate coating to ensure maximum surface strength under subsequent temperature cycling and to prevent peeling of the topcoat..
Overcoating should be carried out before the zinc silicate coating oxidises. Where this is not possible, the zinc silicate surface shall be clean and free from zinc corrosion products.
In corrosive environments, direct use of black Intertherm 50 over zinc silicate primer causes a significant colour change from black to grey due to "salting-out" of the primer beneath. Applying a coat of Intertherm 50 Aluminium before the black Intertherm 50, sealing the zinc silicate primer first, greatly reduces this colour change. The maximum dry heat resistance of this coating system is 400°C (752°F).
Intertherm 50 is not suitable for exposure to acidic or alkaline environments.
Intertherm 50 Aluminium has the following approvals: • BS5493 (1977): CP7 • Shell specification DEP 40.48.00.30 Gen. Chapter Vl (h) Note: VOC values are typical and are given for guidance only. The value may vary with factors such as colour differences and normal manufacturing tolerances.
Although the low-molecular-weight reactive additive becomes part of the film when cured under normal ambient conditions, analysis by EPA Method 24 shows that it also affects the VOC value.
This product is a dedicated coating and can therefore be used only with a limited number of products.
Suitable primers: Interzinc 22, Interzinc 2280. Suitable topcoat: Intertherm 50. For other suitable primers, consult International Paint.
| For further information on the industry standards, terms and abbreviations used in this datasheet, see www.international-pc.com | In the following documents on the website: • Definitions and abbreviations • Surface preparation • Coating application • Theoretical and practical spreading rate. These sections are also available as separate publications on request. |
|---|
This product must be applied at the production site by professional applicators in accordance with the recommendations in this manual, the Material Safety Data Sheet and the instructions on the container label. Do not use this product without first reviewing the Material Safety Data Sheet (MSDS) that International Paint provides for its customers.
All work related to the application and use of this product must be carried out in accordance with the relevant national health, safety and environmental standards and regulations.
If welding or flame cutting is required on metal coated with this product, dust and fumes will be generated; use appropriate personal protective equipment and adequate local ventilation.
If in doubt about the suitability of this product for the intended use, consult AkzoNobel for further advice.
| Packaging Specifications | ||
| Volume | Packaging | |
| 10 L | 6 L | 10 L |
| 5 US gal | 5 US gal |
For other packaging sizes, contact AkzoNobel.
Packaging Specifications
| 10 L | 8.2 kg |
|---|---|
| 5 US gal | 50.5 lb |
| Shelf life | At least 12 months at 25 °C (77 °F). Thereafter, inspection is required. Store in a dry, cool environment away from heat and sources of ignition. |
|---|
© 2026/5/27 AkzoNobel. All rights reserved.
All registered trademarks mentioned in this publication are licensed to or owned by AkzoNobel.
www.international-pc.com
Information is subject to the manufacturer's latest version; the manufacturer's latest TDS prevails.
The technical parameters on this page are taken from the product's original manufacturer technical datasheet, the copyright of which belongs to the manufacturer. If a rights holder considers the presentation inappropriate, contact us for verification and handling.
Packaging specifications and batch lead times are subject to actual availability. PleaseContact Uscontact us for project-based calculation.
Factory stock numbers of Intertherm 50 Silicone Heat-resistant Coating are as follows.Item No.is the most accurate form when ordering;Colour/colour codecorresponds to the actual colour (RAL, GSB are colour chart codes);Packaging SpecificationsFactory complete-set specification format. Colors not listed may be ordered against the colour card.
| Item No. | Colour / colour code | Packaging Specifications |
|---|---|---|
| HTA097 Aluminium | — | 20 L |
| HTA099 | — | 20 L |
This model has a total of2item numbers, all listed on this page; colours outside the table (including special colours and bulk packaging) can be confirmed by phone, delivery dates are advised according to the factory's current production schedule and stock. In the packaging specification, the "+" indicates the complete-set notation for two-component products (base + curing agent), subject to the factory specification; a "—" in the colour column denotes an auxiliary product, or that the item has no colour code in the factory system.
