Which Emulsion Paint Should I Use? Interior Paint Selection Guide

Summary

Interior emulsion selection is one of the most common questions on any decorating job. The wrong product leads to poor coverage, early failure, and callbacks. Most tradespeople default to matt emulsion for everything, but this can be the wrong call in high-humidity rooms or on surfaces prone to scuffing.

The UK paint market splits broadly into trade and retail grades. Trade emulsions — sold by brands like Dulux Trade, Johnstone's, Crown Trade, and Leyland — have higher pigment loads, better opacity, and typically cover 10-14m² per litre vs 8-10m² for retail. That difference matters when you're pricing and quoting coverage.

Understanding the sheen levels and their appropriate applications will prevent problems with condensation, mould, and surface degradation. The right choice upfront saves time on remedial work and keeps customers happy long after the job is done.

Key Facts

• Vinyl matt emulsion — the standard product for ceilings and living areas; low sheen, hides imperfections well, not washable
• Vinyl silk emulsion — high sheen, washable, suits hallways and children's rooms; emphasises surface imperfections
• Soft sheen / eggshell emulsion — mid-sheen compromise; more durable than matt, used in kitchens and bathrooms
• Moisture-resistant emulsion — contains fungicide additives; essential in bathrooms and kitchens above 60% relative humidity
• Anti-mould paint — contains biocides (typically 3-iodo-2-propynyl butylcarbamate, IPBC); effective for 5-10 years depending on conditions
• Contract matt — cheapest trade option; low opacity, high filler content; use only as a mist coat or first coat
• Coverage rate — good trade matt covers 12-14m² per litre; silk 10-12m²; anti-mould 8-10m²
• Drying time — touch dry 1-2 hours; recoat after 2-4 hours minimum; full cure 2-4 weeks
• VOC levels — water-based emulsions are low-VOC; most UK trade emulsions are VOC Category A or B per BS EN 13300
• Spreading rate on new plaster — new plaster absorbs heavily; first coat should be diluted 10% water (mist coat) before full coats
• Typical first-fix substrate — primed plasterboard or skimmed plaster; PVA bonding coat not recommended as final primer under emulsion
• Colour coverage — deep or vibrant colours may need 3 coats; mid-sheen products generally have better opacity than matte for colours
• BS 3900 — the relevant standard for paint testing and performance in the UK

Quick Reference Table

Detailed Guidance

New Plaster — Mist Coat First

New plaster must be fully dry before painting — this typically means 4-6 weeks for traditional sand and cement render, and 2-4 weeks for plasterboard skim in a heated environment. Painting too soon traps moisture and causes peeling.

The mist coat is a thinned-down first coat: dilute standard vinyl matt with 10% clean water. Do not use contract matt as a mist coat — the binder content is too low to seal the surface effectively. Apply the mist coat by roller and allow to fully dry before applying two full coats of finish emulsion.

Never use PVA as a primer under emulsion on skimmed plaster — this creates a bond break between the PVA film and the emulsion. Use a properly diluted mist coat instead.

Kitchens and Bathrooms

Standard vinyl matt will fail within months in kitchens and bathrooms. The moisture causes the paint film to soften, blister, and peel away from the wall. Use minimum a moisture-resistant emulsion; in wet rooms or poorly ventilated spaces, use a dedicated anti-mould product.

Key brands and their bathroom-rated products:

• Dulux Trade: Mouldshield Matt
• Johnstone's: Joncryl Anti-Mould
• Crown Trade: Cleanable Tough Matt
• Leyland: Anti-Mould Matt

Apply in minimum two coats over a primed surface. Ventilation is still essential — anti-mould paint is a secondary measure, not a substitute for adequate extraction (see bathroom ventilation).

Ceilings

Dedicated ceiling paint is formulated with a thicker body to reduce spatter and a flat finish to disguise imperfections created by overhead lighting. Standard vinyl matt works too, but ceiling paint is faster on large areas. Always use a 15mm nap roller on textured ceilings for better coverage into the texture.

Previously Painted Surfaces

On previously painted walls, assess the existing condition first:

1. Check for flaking or peeling — scrape back and prime bare areas
2. Check for contamination — degrease with sugar soap solution before painting
3. Check for mould staining — treat with a 10% bleach solution and allow to dry before applying anti-mould paint
4. Check for nicotine/water staining — use a shellac-based stain blocker before emulsioning (see damp stain blocking)

Matching existing sheen levels matters — applying matt over silk leaves patches visible in raking light.

Choosing Between Brands

All major trade brands produce broadly comparable products at the same price point. The key differences:

Estimating Quantities

Calculate wall area: (length + width) × 2 × height, then subtract doors (approximately 2m²) and windows (approximately 1.5m²).

Divide by coverage rate from the tin. Always add 10% contingency. For a typical UK living room of 4m × 4m × 2.4m:

• Wall area: (4+4) × 2 × 2.4 = 38.4m²
• Less 2 doors and 2 windows = 38.4 - (4 + 3) = 31.4m²
• At 12m² per litre for 1 coat = 2.6 litres
• Two coats = 5.2 litres; buy 2 × 2.5L tins

See tile quantities for the general approach to material estimation.

Frequently Asked Questions

Do I need to prime before emulsioning?

On bare new plaster, yes — use a diluted mist coat (emulsion + 10% water). On previously painted surfaces in good condition, no separate primer is needed. On bare plasterboard, use a proprietary board primer or the mist coat method. On stained or problem areas, use a stain-blocking primer first.

Can I use emulsion on woodwork?

No. Emulsion is formulated for porous mineral substrates. On wood, it will not bond properly, will not flex with movement, and will chip and flake. Use a water-based satinwood or gloss on woodwork (see woodwork prep).

How long should I wait between coats?

Minimum 2 hours at 20°C in normal conditions; longer in cold or damp weather. Do not force-dry with space heaters — rapid drying causes surface skinning before the paint beneath has cured, leading to cracking. In winter on site, allow 4 hours between coats minimum.

My paint is covering unevenly — why?

The most common causes: 1) new plaster not mist-coated first, 2) applying over a contrasting colour without adequate coats, 3) paint too thin on the roller (charging up on a dry roller tray), 4) cheap paint with low pigment load. Switch to a trade product with a stated opacity of Class 1 or 2 per BS EN 13300.

Is more expensive paint worth it for trade work?

Generally yes. The coverage rate difference between a £12/5L and a £25/5L trade emulsion can be 30-40% better opacity — meaning fewer coats, less time on site, and a better finish. On price-sensitive jobs, factor in the labour cost of an extra coat vs the material saving.

Regulations & Standards

• BS EN 13300 — European standard for water-borne coating products; classifies sheen (G1-G6), opacity (Class 1-4), and wet scrub resistance

• BS 3900 — series of British Standards for paints; covers adhesion, flexibility, drying time, and other performance characteristics

• Control of Substances Hazardous to Health (COSHH) Regulations 2002 — applies to biocides in anti-mould paints; obtain and review SDS before using in occupied buildings

• Biocidal Products Regulation (BPR) 528/2012 (retained in UK law) — covers active biocide ingredients in anti-mould products; products must be registered

• VOC Regulations — The Paints (Volatile Organic Compounds) Regulations 2012 set maximum VOC limits for decorative paints sold in the UK

• Dulux Trade Product Guide — product specifications and application guidance

• Johnstone's Trade Technical Datasheets — coverage rates and substrate recommendations

• British Coatings Federation — industry guidance on paint standards and VOC compliance

• HSE — COSHH in the Workplace — guidance on working with biocidal products

• damp stain blocking — when to use shellac and stain-blocking primers before emulsioning

• paint coverage rates — calculating how much paint you need

• woodwork prep — primer and undercoat selection for wood surfaces

• skim coat — ensuring the surface is ready before painting

• bathroom ventilation — ventilation is the first defence against bathroom mould