Coo-Var Acrylic Primer Sealer Undercoat | Water-Based Low-Odour Primer for Wood, Plaster & Most Surfaces

• Prime new or bare plaster before applying a topcoat — seals the surface and prevents paint sinkage
• Prime bare wood, MDF or sheet materials inside or outside before topcoating
• Use a single primer that works across multiple surfaces to simplify stock and reduce waste
• Apply a low-odour, low-VOC primer in an occupied or semi-occupied space
• Achieve a fast turnaround — touch dry in 30 minutes, topcoat the same day after 6 hours
• Use a non-flammable, water-based product that cleans up with water

• The surface or air temperature is at or below 7°C during painting or drying — do not apply in cold conditions
• The surface is contaminated with oil or grease and has not been cleaned — contamination will cause adhesion failure
• You require a primer specifically formulated for ferrous metals — use a dedicated metal primer for iron and steel

Coo-Var Acrylic Primer Sealer Undercoat is a water-based, low-odour acrylic primer formulated to prime and seal most surfaces inside and outside. Developed by Coo-Var — a British coatings manufacturer with over 115 years of heritage — it is designed for plaster preparation and wood priming, and can be applied direct to a wide range of substrates before any suitable topcoat.

The water-based formulation delivers a very low VOC content of just 30 g/litre — well below the threshold for most low-VOC classifications — making it one of the most environmentally considerate primers available. It is non-flammable, cleans up with water and is safe to use in occupied or semi-occupied spaces. Touch dry in just 30 minutes at 20°C, it allows topcoating the same day after a minimum of 6 hours.

Its versatility is a key advantage — a single product that primes and seals wood, plaster, masonry and most other surfaces, reducing the number of products needed on site and simplifying stock management for decorators and contractors.

Key Benefits

• Extremely low VOC — max 30 g/litre, well below standard low-VOC thresholds, safe for use in occupied spaces
• Touch dry in 30 minutes — one of the fastest-drying primers available, topcoat the same day
• Non-flammable — water-based formula with no flammability risk, safe to store and use
• Versatile multi-surface primer — suitable for wood, plaster, masonry and most surfaces inside and outside
• High coverage — 13 m² per litre at 35 micron DFT, cost-effective for large areas
• Cleans up with water — no solvents required for tool cleaning
• 115+ years of British expertise — trusted by decorators, contractors and homeowners across the UK

Order before midday for next-day UK delivery.

Coo-Var Acrylic Primer Sealer Undercoat is an excellent choice for priming and sealing a wide range of surfaces in residential, commercial and industrial settings:

• New Plaster & Plastered Surfaces — Seal new or bare plaster before applying emulsion or other topcoats. Prevents paint sinkage on porous plaster, reduces topcoat consumption and ensures a consistent, even finish. Touch dry in 30 minutes allows topcoating the same day.

• Bare Wood & Timber — Prime bare wood, softwood, hardwood and exterior timber before applying a topcoat. Seals the grain, prevents sinkage and provides a sound base for water-based and oil-based topcoats. Suitable for interior joinery, exterior cladding and garden structures.

• MDF & Sheet Materials — Apply to bare MDF, plywood and other sheet materials before topcoating. Seals the surface effectively without grain raise, providing a smooth, consistent base for a high-quality finish.

• Masonry & Render — Prime external masonry, render and brickwork before applying a masonry topcoat. Seals porous surfaces and improves topcoat adhesion and coverage on exterior walls and facades.

• Occupied & Sensitive Environments — The non-flammable, low-VOC formula (max 30 g/litre) makes it safe to use in schools, hospitals, offices and other occupied spaces where solvent-based products are not appropriate. No fire alarm risk and minimal odour disruption.

• Multi-Surface Decorating Projects — Use as a single primer across multiple substrates on the same project — wood, plaster, masonry and MDF — simplifying stock, reducing waste and speeding up project turnaround.

If you need personalised advice on surface preparation or compatible topcoats, contact our experts via the live chat for tailored guidance.

Coverage: 13 m² per litre at 35 micron dry film thickness

Coverage per size

• 2.5L tin: Covers approximately 32.5 m² per coat
• 5L tin: Covers approximately 65 m² per coat

Recommended coats

• 1 coat is standard on previously painted or sealed surfaces in good condition
• 2 coats recommended on new plaster, bare wood or very porous surfaces for full sealing and adhesion
• Recoat after a minimum of 6 hours at 20°C

Example calculations

• For a standard bedroom (approximately 40 m² of walls and ceiling), a 2.5L tin will cover 1 coat; a 5L tin will cover 1 coat with material to spare for a second coat on bare areas
• For new plaster in a living room (approximately 30 m²), a 2.5L tin will cover 1 coat; allow for a second coat on very porous areas
• For bare wood joinery and doors in a house (approximately 15 m²), a 2.5L tin will cover 2 coats

Practical coverage may be lower on very porous or rough surfaces such as new plaster, bare brick or rough timber. For accurate project planning, we recommend ordering 10–15% extra.

Thin with clean water at a maximum of 10% if required.

Surface Preparation

New Wood
• Sand prior to coating to ensure an adequate key
• Ensure the surface is clean, dry and free from contaminants

New Plaster
• Allow new plaster to cure fully before applying — plaster must be dry and sound
• Apply direct to clean, dry plaster

Masonry and Render
• Ensure the surface is clean, dry, sound and free from contaminants
• Remove any loose or friable material before priming

Existing Painted Surfaces
• Clean, degrease and sand to ensure an adequate key
• Remove all loose and flaking material and treat bare areas as new substrate

All Surfaces
• All surfaces must be clean, dry, sound and free from contaminants before priming
• Do not apply when the temperature is at or below 7°C during painting or drying

Application

1. Mix the paint well before use
2. Thin with clean water at a maximum of 10% if required
3. Apply by brush, spray or roller to the prepared surface
4. Apply evenly, ensuring full coverage
5. Allow to dry — touch dry in 30 minutes, recoat after a minimum of 6 hours at 20°C
6. Clean tools immediately after use with clean water

Drying Times (at 20°C)

• Touch dry: 30 minutes
• Hard dry: 2 hours
• Full hardness: 5–7 days
• Recoat interval: 6 hours

Drying times will be longer in cold or humid conditions. Do not apply when the temperature is at or below 7°C.

Important Notes

• Apply direct to most surfaces — no separate primer required
• Suitable for interior and exterior use
• Non-flammable — safe to store and use in occupied spaces
• Topcoat with any suitable topcoat after a minimum of 6 hours

Recommended System Products

Free delivery on orders over £75 — stock up on everything you need in one go and complete the job properly.

Paint Brushes, Rollers & Frames: Use suitable brushes for application. Clean with water immediately after use.

These products are commonly combined for best long-term results.

What surfaces can Coo-Var Acrylic Primer Sealer Undercoat be applied to?
It is suitable for most surfaces including wood, plaster, masonry, render and MDF, for interior and exterior use. All surfaces must be clean, dry and free from contaminants before priming.

Do I need a separate primer before applying this product?
No. It can be applied direct to most surfaces without a separate primer. On new plaster, allow the plaster to cure and dry fully before applying.

What topcoats are compatible?
It is compatible with any suitable topcoat. Apply topcoat after a minimum of 6 hours at 20°C.

What colours are available?
White only.

What pack sizes are available?
2.5L and 5L tins.

How quickly does it dry?
Touch dry in 30 minutes at 20°C. Hard dry in 2 hours. Full hardness is achieved in 5–7 days. Drying times will be longer in cold or humid conditions.

How soon can I apply a topcoat?
Apply topcoat after a minimum of 6 hours at 20°C.

How much does it cover?
Coverage is approximately 13 m² per litre at 35 micron dry film thickness. A 2.5L tin covers approximately 32.5 m² per coat and a 5L tin covers approximately 65 m² per coat. Coverage will be lower on very porous surfaces such as new plaster or bare brick.

Can I thin it?
Yes. Thin with clean water at a maximum of 10%. Clean tools with water after use.

Is it suitable for new plaster?
Yes. It is specifically designed for plaster preparation. Allow new plaster to cure and dry fully before applying.

Is it low odour?
Yes. The water-based formula has a VOC content of just 30 g/litre — well below standard low-VOC thresholds — making it safe to use in occupied or semi-occupied spaces.

Is it flammable?
No. This product is non-flammable.

What temperature do I need to apply it?
Do not apply when the temperature is at or below 7°C during painting or drying.

Do you offer next-day delivery?
Yes. Order before midday for next-day delivery to mainland UK addresses. Contact us for delivery options to Scottish Highlands, Northern Ireland and other remote areas.

Safety data sheet
Technical data sheet

We recommend these system products to achieve the best results with Coo-Var Acrylic Primer Sealer Undercoat. Free delivery on orders over £75

Paint Brushes, Rollers & Trays — suitable brushes for primer application; clean with water immediately after use

Not sure which topcoat is right for your surface? Contact our experts via live chat for free, tailored advice — we will help you choose the right products and get the best result.

Fast, Reliable & Fully Tracked UK Delivery

Every order is dispatched from our warehouse using a fully tracked DX or FedEx service, so you always know when your paint will arrive.

Delivery Options

• FREE Standard Delivery (orders over £75) Arrives in 2–3 working days
• Standard Delivery – £7.95 Arrives in 2–3 working days
• Express Delivery – £13.95 Next working day delivery when you order before 12:00 noon (Mon–Thu)
• Spending £75+? Select Express Upgrade at checkout and only pay the difference

Dispatch & Delivery Times (What Happens After You Order)

• Express delivery (order before 12:00 Mon–Thu) Dispatched same day, delivered next working day
• Standard delivery (Mon–Wed orders) Dispatched next working day, delivered 2–3 working days later
• Orders placed Thursday (standard delivery) Dispatched Friday for Monday delivery
• We do not dispatch or deliver on weekends or UK bank holidays

What to Expect on Delivery

Please provide a contact telephone number at checkout. This allows the courier to share tracking updates or contact you if there are any delivery issues.

Most orders require a signature on delivery. If you may not be available during the day, we recommend delivery to a workplace, business address, or another location where someone can sign.

Outside the UK Mainland?

Delivery prices shown apply to UK Mainland only.

For the Highlands, Islands, Northern Ireland, or non-mainland addresses, please contact us for a quick personalised quote via live chat, by calling 01482 222 421, or emailing info@specialistpaintsonline.co.uk.

Bottom Line

Order today, get fast and reliable delivery, track every step, and get painting without delays.