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Bollom Intulac Ultra Intumescent Clear Basecoat
A water-based clear intumescent basecoat for interior wood, providing fire protection as part of the complete Intulac Ultra system.
Features
- Achieves Class B-s1, d0 to BS EN 13501-1:2018 when used with Intulac Ultra Topcoat as part of the specified three-coat system
- Forms a protective carbon char when exposed to fire, helping to delay ignition of the wood
- Clear basecoat preserves the visible wood grain as part of the complete varnish system
- Suitable for bare wood or up to four sound, well-adhered coats of existing varnish, reducing the need for complete stripping
- Single-pack formulation requires no mixing of separate components, simplifying preparation
- Can be applied by brush, roller or airless spray to suit the project and surface area
- Water-based formulation allows tools to be cleaned with warm water after use
Brand
Drying time
48 hrs
Coverage
Up to 5 m2 per litre
No. of coats
2
Size
5L
MPN
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GTIN
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Overview
Bollom Intulac Ultra Intumescent Clear Basecoat forms the fire protective layer of the Intulac Ultra varnish system. This water-based coating preserves the appearance of interior wood while producing an insulating carbon char when exposed to fire, helping to delay ignition.
Two coats of basecoat, sealed with the specified protective topcoat, provide a system classified as B-s1, d0 to BS EN 13501-1:2018. The classification covers three aspects of its performance during testing:
- B denotes a limited contribution to the development of fire
- s1 identifies low smoke production
- d0 confirms no flaming droplets or particles within the specified test period
Suitability
Use on suitable interior hardwood, softwood, plywood, chipboard, hardboard and fibre insulation board. Veneering must be at least 9mm thick. Previously varnished wood can also be treated, provided no more than four single coats remain and each is sound and firmly adhering.
Surfaces subject to mechanical stress, including floors, stairs and doors, are excluded. Prepare the timber and apply the coating at the rates specified by Bollom for bare or previously varnished wood.
Complete the System
The basecoat requires one coat of Bollom Intulac Ultra Topcoat to seal and protect it. Choose a matt or satin finish to retain the visible grain and complete the three-coat system.
The Class B-s1, d0 rating depends on using both products at their specified coverage rates. Apply the topcoat approximately 48 hours after the final basecoat, and no later than four days.
Preparation
Preparation
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Prepare bare or previously varnished interior wood thoroughly before applying Bollom Intulac Ultra Intumescent Clear Basecoat. The surface must be clean, dry and sound, with a timber moisture content below 15%.
Older paint coatings, particularly those applied before the 1960s, may contain lead. If these are present, seek advice on safe preparation before sanding or stripping.
- Remove dust, dirt and any loose surface material
- Clean away oil, wax, grease and release agents with a suitable cleaner, such as Zinsser Universal Degreaser and Cleaner ensuring no residues remain and allowing the wood to dry fully
- Check existing varnish for adhesion. No more than four single, sound, firmly adhering coats may remain
- Scrape loose or flaking varnish back to a firmly adhering surface. If adhesion is uncertain, remove all existing varnish back to bare wood
- Lightly sand sound existing varnish before coating with Woodleys Flexible Sanding Pads. Thoroughly abrade wood that is difficult to wet so the basecoat can wet the surface evenly
- Inspect for damaged timber, cracks and holes, and complete any necessary repairs. Confirm compatible fillers and repair materials with Bollom before use
- For particularly resinous or knotty timber, apply one coat of Zinsser SealCoat as specified by Bollom
Remove all sanding dust and check that the surface is dry and free from contamination before applying the basecoat.
Application
Application
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Always apply to a small test area before starting to check compatibility and the final appearance. Follow the manufacturer's instructions on the tin and the current Technical Data Sheet.
The surface temperature must be between 10°C and 40°C and at least 3°C above the dew point. Relative humidity should not exceed 70%. Maintain suitable conditions during application and drying to prevent condensation.
- Stir thoroughly before use using a Mako Paint Stirrer and apply undiluted
- Apply by brush, roller or airless spray
- Apply two coats at 5m² per litre per coat on bare timber, or 4m² per litre per coat on previously varnished timber. Follow these specified rates to achieve the required coating build
- Allow at least 16 hours between basecoat coats. Lower temperatures and higher humidity may extend drying times
- If required, lightly sand after the first coat with 150-grit abrasive paper to remove raised wood fibres, then remove the sanding dust before continuing
- Allow approximately 48 hours after the final basecoat before applying the protective topcoat, and complete topcoating within four days
For airless spraying, use equipment with a pump ratio of at least 30:1, a hose diameter of at least 3/8 inch and a recommended nozzle size of 0.011-0.015 inch (0.28-0.38mm). Use solvent-resistant hoses as specified by Bollom.
Drying times are based on 20°C and 60% relative humidity. Do not stack timber components treated with the Intulac Ultra system.
Bollom Intulac Ultra Intumescent Clear Basecoat must be finished with Bollom Intulac Ultra Topcoat. Apply one coat of the topcoat at 20m² per litre to complete the specified Class B-s1, d0 system. Do not substitute another varnish, as the stated fire classification applies to the complete specified Intulac Ultra system.
Finishing
Finishing
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Complete the project by applying Bollom Intulac Ultra Topcoat, available in matt and satin sheens. This clear protective finish seals the basecoat while keeping the wood grain visible.
The specified topcoat is essential to achieve the complete system's Class B-s1, d0 fire classification. Apply one coat at 20m² per litre, approximately 48 hours after the final basecoat and within a maximum of four days. Do not substitute another varnish.
F.A.Q.
F.A.Q.
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How do I get Fire Certification?
Keep your proof of purchase, the batch numbers of the products used and the site details. Submit this information through Bollom's website to request the relevant Certificate of Supply, which Bollom states will be sent within 5 working days.
Can I use the basecoat without a topcoat?No. Bollom Intulac Ultra Intumescent Clear Basecoat must be finished with Bollom Intulac Ultra Topcoat. The Class B-s1, d0 classification applies to the specified three-coat system, comprising two coats of basecoat and one coat of topcoat.
Can I apply it over existing varnish?Yes, over a maximum of four single, sound, well-adhered coats of varnish. Remove loose or flaking areas and lightly sand the remaining finish before application. If adhesion is uncertain, remove the existing varnish back to bare wood.
Will the wood grain remain visible?Yes. The basecoat and its compatible protective topcoat are clear, allowing the wood grain to remain visible. Always complete a small test area first to check the appearance on your chosen timber.
Why are the application rates different for bare and previously varnished wood?Bollom specifies different coating builds for these surfaces to achieve the stated fire classification. Apply each basecoat coat at 5m² per litre on bare timber or 4m² per litre on previously varnished timber. These are required application rates, rather than maximum coverage estimates.
Can I use it on doors, floors or stairs?No. Bollom excludes surfaces exposed to mechanical stress, including doors, floors and stairs. The system is intended for suitable interior wood surfaces within the manufacturer's specification.
How long should I wait before applying the topcoat?Allow approximately 48 hours after the final basecoat and apply Bollom Intulac Ultra Topcoat within a maximum of four days. These timings are based on 20°C and 60% relative humidity; lower temperatures and higher humidity can extend drying times. If these conditions affect the specified overcoating window, seek advice from Bollom before proceeding.