Dulux Stain Block Primer and Undercoat White

Description

Dulux Stain Block Primer and Undercoat White – Heavy-Duty Base Coat for Stain-Prone Surfaces

Dulux Stain Block Primer and Undercoat White is a specialist preparatory coating engineered to seal, block and isolate stubborn stains on interior wood, plaster and previously painted surfaces ahead of decoration. This high-performance primer and undercoat is formulated to prevent common discolouration sources — including water marks, nicotine staining, smoke residue and felt-tip or crayon marks — from bleeding through topcoats. As a result, it creates a stable, clean base for decorative finishes.

Whether you’re preparing walls after renovation, dealing with stain-affected plaster, or refreshing painted woodwork, Dulux Stain Block Primer and Undercoat White helps deliver a professional-looking, long-lasting finish.

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Key Features & Benefits

• Advanced stain-blocking technology – Prevents stains, discolouration and bleed-through from affecting your decorative topcoat.

• Prime and undercoat in one – Combines primer and undercoat performance to save time and effort.

• Pure white base – Enhances topcoat colour accuracy and improves coverage.

• Excellent adhesion – Supports strong, uniform bonding of subsequent paints.

• Interior use – Designed primarily for indoor applications where stains are a concern.

• Compatible with Dulux topcoats – Ideal under Dulux Matt Emulsion, eggshell, satinwood or gloss finishes.

This product is a go-to solution for decorating over surfaces where simple cleaning and standard primers may not deliver reliable results.

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Where to Use Dulux Stain Block Primer and Undercoat White

Dulux Stain Block Primer and Undercoat White is suitable for interior surfaces affected by:

• Water stains and damp patch residue

• Nicotine or smoke staining

• Felt-tip pen, crayon or grease marks

• Tannin bleed from timber knots

• Renovation areas with residual discolouration

Before decorating, ensure that underlying causes of staining are addressed (e.g., leaks or condensation), and clean surfaces wherever possible. This stain-blocking primer prepares the substrate to ensure decorative topcoats deliver consistent colour and finish.

For general surface preparation and sealing, see our wall primers & sealers range.

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Technical Specifications

*Coverage figures are approximate and will vary with substrate porosity and application method.

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How to Apply – Best Practice Guide

1. Surface Preparation: Remove loose paint, dirt and grease. Lightly sand glossy areas to improve surface key.

2. Clean Surface: Where possible, wipe down surfaces with a damp cloth or mild detergent solution to remove any residue. Allow to dry thoroughly.

3. Stir Paint: Stir the primer and undercoat thoroughly before use and periodically during application.

4. Apply Evenly: Use quality brushes or rollers from our paint brushes & rollers collection. Apply in smooth, overlapping passes.

5. Dry & Recoat: Allow to dry (typically 4–6 hours), then apply the chosen Dulux topcoat for your desired finish.

Using a dedicated stain-blocking primer ensures that problematic discolouration doesn’t compromise the appearance or performance of your decorative paint.

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External Manufacturer Reference

For full technical specifications and official product guidance, visit the Dulux Stain Block Primer and Undercoat White page on the Dulux UK website. (external link)
https://www.dulux.co.uk/products/dulux-stain-block-primer-and-undercoat

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Frequently Asked Questions – Dulux Stain Block Primer and Undercoat White

What stains can this product block?
This primer is formulated to block water stains, smoke and nicotine marks, crayon or felt-tip stains, tannin bleed from wood knots, and residual discolouration on interior surfaces.

Is this product suitable for exterior use?
This primer is designed primarily for interior use. For exterior staining issues, use products specifically formulated for outdoor environments.

Do I need to treat mould or damp before using this primer?
Yes. Address underlying causes of mould or damp — such as leaks or condensation — and treat affected surfaces with an appropriate fungicidal wash before priming.

How long before I can topcoat?
Under normal conditions, allow the primer to dry for approximately 4–6 hours before applying a decorative topcoat.

Can this be used under any Dulux topcoat?
Yes. It is compatible with Dulux matt, eggshell, satinwood and gloss finishes when applied correctly.