IRIS CHAR 17 INTUMESCENT CLEAR VARNISH 5L
What is this product?
CHAR 17 is a base coat and requires a protective topcoat of CHAR 17 Finish (available separately). The topcoat must be applied to achieve full moisture resistance and ensure long-term performance.
CHAR 17 Clear Intumescent Base Coat
CHAR 17 is an advanced, waterborne intumescent clear coating engineered to provide fast-acting, low-temperature fire protection for timber substrates while preserving the natural appearance of the wood grain. When exposed to heat, the thin transparent film rapidly expands into an insulating carbon char barrier that dramatically delays ignition and suppresses flame spread.
When applied at the certified application rate, CHAR 17 achieves a Euroclass B-s1, d0 reaction-to-fire classification on wood-based substrates of 10 mm thickness or greater.
Key Features
- Clear, transparent finish maintains natural architectural timber appearance
- Achieves Euroclass B-s1, d0 reaction to fire rating
- Rapid intumescent activation at low temperatures
- Suitable for non-traffic interior wooden structures, beams, columns, joists, studs, and decorative cladding
- Low-odour, waterborne formulation
Application & Coverage
| Base Coat Coverage | 2 coats at 125 ml/m² (total 250 ml/m² / 4 m² per Litre) |
| Topcoat Coverage | 50 ml/m² (approx. 20 m² per Litre of CHAR 17 Finish) |
| Application Tools | Fine or short-pile roller (preferred), or brush (take care to ensure even wet film) |
| Working Temperatures | Between +15 °C and +35 °C |
| Humidity Limits | Max. 70% Relative Humidity |
| Substrate Moisture | Wood moisture content must be below 15% to prevent clouding/white spots |
Application Instructions
- Surface Preparation: Strip all existing paints, varnishes, and non-breathable sealers. Oiled or waxed surfaces must be spot-checked for adhesion and optical clarity; oils and waxes must be fully cured to prevent reaction issues.
- Handling: Do not handle dry-to-the-touch surfaces with bare hands prior to topcoating to avoid transferring oils and fingerprints into the film.
- Topcoating Schedule: CHAR 17 Finish must be applied on the same day as the base coat. Delaying the topcoat leaves the uncapped intumescent salt layer exposed to ambient moisture, which can compromise the clarity and final cure.
- Limitations: Interior use only. Not suitable for external applications, areas exposed to regular water contact, high-humidity zones, or high-wear flooring surfaces.
Testing & Certification Standards
- Reaction to Fire: Classified Euroclass B-s1, d0 in accordance with EN 13501-1
- Test Methods: Tested according to EN ISO 11925-2 and EN 13823 on wood particleboard rated to EN 312-2
- Field of Application: Per EN 13823 paragraph 5.2, test performance applies across standard timber, wood-based substrates, and substrates rated Euroclass A2 or better when applied at 300 g/m² active layer weight
Downloads
Product information provided on this website is for guidance purposes only. We advise all customers to contact our technical department for a free, no-obligation project specification before purchasing goods directly.
Please note: Products purchased directly without an approved specification will not qualify for formal project certification. Failure to obtain correct technical guidance absolves Eco-Sol Ltd from liability resulting from incorrect product selection, improper application rates, or non-compliant fire performance.
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Waterborne intumescent formulation
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Fast activation at low temperature
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Transparent finish preserves the timber's natural appearance
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Achieves Euroclass B-s1-d0 on wood-based substrates 10mm or more
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Backed by multiple European test/certification bodies (LAPI, GTC, PAVUS, PROPLAST, SWEDCERT, NRC Cairo)
Specifications & Documents
Full technical data and downloadable certification for compliance records.
| Product Code | Char 17 Base |
| Suitable For | Interior timber elements not subject to heavy wear and tear — beams and columns, boards, studs and joists, decorative panels or walls. |
| Finish | Transparent 2 pack system. Intumescent base coat and Sealant top coat |
| Use | Interior use only, for fire protection of wooden structures and panels not subject to strong wear and tear — e.g. beams, columns, boards, studs, joists, decorative panels, walls. |
| Application Method | Airless or airmix spray, roller, or brush. Fine or small/short pile roller recommended for best results. |
| Fire Classification | Euroclass B-s1-d0 on wood-based substrates of 10mm or more, per EN 13501-1. Classification tests per EN ISO 11925-2 and EN 13823. |
| British Standard | BS EN13501-1 |
| VOC Content | Waterborne intumescent clear coating. Density 1.30 ± 0.05 kg/dm³ at 20°C. Solids content 60% ± 5% w/w, 75% ± 5% v/v. Colour: transparent. |
| Shelf Life | 12 months in original packing, stored in the proper environment. |
| Coverage | 4.0 m² per litre |
How to Apply
Simple application with standard tools — no specialist equipment required.
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1Prepare surfaceRemove existing coatings. Spot-check oiled or waxed timber beforehand to ensure full adhesion and clarity of the final product; oil/wax must be fully dry per manufacturer instructions before applying.
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2Apply base coatApply 2 coats at 125ml per m² using a fine or small pile roller for best results. Take care with brush application to ensure even coverage.
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3Apply topcoatProtect with CHAR 17 Finish on the same day as initial application. Delaying the topcoat risks humidity affecting the final finish.
Coverage Guide
Frequently Asked Questions
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No. CHAR 17 is for interior use only and should not be applied externally or in areas of high humidity.
Yes. CHAR 17 must be protected with CHAR 17 Finish on the same day as initial application. Delaying the topcoat risks humidity affecting the final finish.
CHAR 17 achieves Euroclass B-s1-d0 on wood-based substrates of 10mm or more, tested to EN 13501-1.
CHAR 17 base coat is applied at 125ml per m² per coat, 2 coats, giving 4m² per litre.
By airless or airmix spray, roller, or brush. A fine or small pile roller gives the best results.
12 months in original packing, stored in the proper environment.
Temperature between 15°C and 35°C, relative humidity no higher than 70%, and wood moisture below 15% to avoid white spot formation.
What Our Customers Say
Verified reviews collected via eKomi — independently moderated and genuine.
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★★★★★
Gave them a ring to ask for some advice, was pointed to exactly what I needed and how much. Arrived promptly and has performed perfectly.
Verified purchase · 2 weeks ago -
★★★★★
Very quick response to query and fast delivery. Easy to use product with good instructions. Great company. Will use again.
Verified purchase · 1 month ago -
★★★★★
Excellent product with swift delivery. Easy to top up fire retardancy after the deck was cleaned. Looks completely untreated which was exactly what we wanted.
Verified purchase · 1 month ago