Ready mixed plaster gives installers a fast, reliable way to achieve a smooth, paint-ready finish on internal walls and ceilings, without measuring powder and water on site for every batch.

Supplied as a factory-prepared paste, ready-mixed plaster helps simplify preparation, improve consistency between applications and offer flexibility across hand, roller and machine methods. But even with a ready-to-use product, the quality of the final finish still depends on correct substrate preparation, the right application thickness and suitable drying conditions.

This guide explains how ready-mixed plaster works, where it can be used, and the best-practice approach to application using PRO-570 Ready Mixed Plaster.

Key points at a glance

• Polymer-modified, ready-to-use paste for internal walls and ceilings
• Apply by trowel, roller or spray up to 2mm per coat
• Dries in approx. 2 hours at +20°C; hardens in approx. 24 hours
• Coverage approx. 2kg/m²/mm, supplied in 18kg units
• Sandable once fully dry for a high-quality painted finish

What is ready mixed plaster?

Ready mixed plaster is an internal finishing material supplied as a pre-prepared paste. Unlike traditional powdered plaster, which must be mixed with water before use, a ready mixed product is prepared during manufacture and applied once it has been thoroughly re-mixed on site.

PRO-570 Ready Mixed Plaster is a polymer-modified internal finishing plaster designed to create a smooth, high-quality surface on walls and ceilings before painting or decorative finishes. Its smooth, thixotropic consistency allows it to be applied using a steel trowel, a roller or suitable spray equipment, giving installers flexibility depending on the area, project requirements and preferred method.

Where can ready mixed plaster be used?

PRO-570 is designed for internal use only and can smooth suitable walls and ceilings before decoration. Compatible substrates include:

• Gypsum plaster
• Plasterboard
• Cement-lime plaster
• Concrete
• Reinforced concrete

The substrate must always be sound, dry, stable and correctly prepared before application.

Ready mixed plaster is a finishing material, not a substitute for products designed to correct significant substrate irregularities or build up substantial thickness. PRO-570 has a maximum recommended application thickness of 2mm per coat.

Why use ready mixed plaster?

The main benefit for installers is the reduction in on-site preparation. Traditional powdered materials require water to be measured and mixed before each batch; a factory-prepared product removes much of that process. In practice, this brings several advantages.

Consistent material. Because the paste is factory prepared, its consistency is controlled during manufacture, reducing variation between batches and giving more predictable workability across a project.

Reduced preparation. PRO-570 only needs to be stirred thoroughly before use,  there’s no need to measure powder and water for every batch.

Flexible application methods. The product can be applied by hand, roller or suitable spray equipment, so installers can choose the method that best suits the scale of the job and the control required.

Fine, sandable finish. Once fully dry, the surface can be sanded by hand or mechanically to remove minor irregularities before decoration,  useful wherever a high-quality painted finish is needed.

Ready mixed plaster vs traditional powdered plaster

Both can be used in internal finishing work, but their preparation and application differ.

Traditional plaster is supplied as a powder and mixed with water on site, so the installer controls the water ratio, mixing and consistency. Ready mixed plaster is supplied as a prepared paste, removing many of these stages.

Application thickness is another key difference. PRO-570 is a thin finishing plaster with a maximum recommended thickness of 2mm per coat, intended to smooth a suitable background rather than build out deep areas or correct major defects.

The correct material should be selected according to substrate condition, required build thickness, desired finish, application method, project size and site conditions. Ready mixed plaster is not automatically a direct replacement for every traditional system.

Is ready mixed plaster the same as multi-finish plaster?

No. Both can create smooth internal surfaces, but they are different products. Traditional multi-finish plaster is generally supplied as a dry powder and mixed with water immediately before use, whereas PRO-570 is a ready-to-use, polymer-modified paste. They can also differ in recommended thickness, drying characteristics and finishing process.

When choosing between them, consider the substrate, required thickness, working method and the manufacturer’s technical guidance rather than treating the products interchangeably.

Preparing the substrate

Correct preparation is essential when applying a thin finishing plaster. The background must be:

• Clean
• Dry
• Stable and load-bearing
• Free from dust
• Free from grease, lubricants and release agents
• Free from paint residues and other contaminants that may affect adhesion

Remove any loose, unstable or poorly adhered coatings, and thoroughly clean oily or contaminated surfaces. Because ready-mixed plaster is applied as a relatively thin layer, imperfections or movement within the substrate can affect the final surface, so assess areas prone to cracking before application.

Reinforce junctions between different substrates, installation chases and other vulnerable areas with suitable fibreglass mesh where required.

Preparing PRO-570 ready mixed plaster

PRO-570 is supplied ready to use but should still be mixed thoroughly before application. Stir the full contents until a uniform consistency is achieved.

For roller or machine application, a small amount of clean water can be added where necessary to adjust the consistency. Water addition should not exceed approximately 1.7% per unit, and the product should always be mixed thoroughly before deciding whether extra water is needed.

Material that has already started to harden must not be re-mixed.

How to apply ready mixed plaster

PRO-570 can be applied by steel trowel, roller or suitable spray equipment.

Step 1 — Check the substrate. Confirm the background is clean, dry, sound and stable. Remove loose material, dust and contamination before you begin.

Step 2 — Mix the product. Stir PRO-570 until the texture is consistent. Only add water where necessary for roller or machine application, staying within the recommended limit.

Step 3 — Apply an even coat. Spread the plaster evenly and work it firmly into the surface to create a uniform layer, up to a maximum of 2mm per coat.

Step 4 — Apply additional coats where required. If more than one coat is needed, allow the previous coat to set before applying the next. Don’t exceed the recommended thickness in a single application.

Step 5 — Allow the surface to dry. At approximately +20°C, PRO-570 has a stated drying time of around 2 hours and an approximate hardening time of 24 hours. Actual times vary with temperature, humidity, ventilation, substrate and application thickness, always assess the material and site conditions rather than relying solely on stated figures.

Step 6 — Sand the surface. Once completely dry, sand out any minor unevenness by hand or mechanically using suitable abrasive paper or sanding cloth. Remove all dust before priming, painting or any decorative work.

Application conditions

Apply PRO-570 when the temperature of the air, substrate and material is between +5°C and +30°C. The background must be fully settled, dried and stabilised before finishing begins.

Take particular care on newly constructed walls and concrete elements, where residual moisture or movement may still be present. Once application is complete, ventilate rooms appropriately to support drying.

Application by trowel

Steel trowel application gives a high degree of control. Spread the plaster evenly and work it firmly into the substrate while maintaining the recommended coat thickness. Trowel application suits smaller areas, detailed finishing, repairs and refurbishment, and anywhere greater control is required.

Application by roller

Roller application is an efficient way to distribute plaster over larger wall areas. Where required, adjust the material with a small quantity of clean water, without exceeding the maximum recommended addition — then work and finish the surface with suitable tools.

Machine application

PRO-570 is also suitable for suitable spray equipment, which can increase productivity on larger internal areas. Equipment should be appropriate for the material and cleaned immediately after use. As with every method, correct substrate preparation and control of coat thickness remain essential.

How much ready mixed plaster do I need?

The approximate consumption rate for PRO-570 is 2kg/m²/mm, and it is supplied in 18kg units. Application thickness and substrate condition directly influence the total material required.

Treat consumption figures as approximate, actual usage varies with substrate flatness, surface texture, application thickness, application method, site conditions and installer technique. Always allow for normal project variation and wastage.

Technical data for PRO-570

Technical property	Value
Composition	Acrylic polymer dispersion in water, additives, pigments and water
Colour	White
Quantity per unit	18kg
Application thickness	Up to 2mm per coat
Consumption	Approx. 2kg/m²/mm
Application temperature	+5°C to +30°C
Drying time	Approx. 2 hours at +20°C
Hardening time	Approx. 24 hours
Adhesion to concrete	≥ 0.3 MPa
Adhesion to gypsum plasterboard	≥ 0.15 MPa

Technical figures may vary depending on the substrate, environmental conditions and application method.

Common mistakes when applying ready mixed plaster

Applying too thickly. Keep to a maximum of 2mm per coat. Where more build is required, use successive coats rather than one heavy application.

Applying over a poor substrate. Loose coatings, dust, grease and contaminants reduce adhesion. Preparation should never be skipped just because the material is ready mixed.

Adding too much water. Only add water where necessary for roller or machine application, and never exceed approximately 1.7% per unit. Excess water alters the product’s intended characteristics.

Sanding before the material is dry. Let the plaster dry completely first, sanding prematurely can damage the surface and make a uniform finish harder to achieve.

Ignoring substrate junctions. Movement between different substrates can cause cracking. Install suitable fibreglass mesh across vulnerable joints and installation chases where reinforcement is needed.

Best practice for a smooth internal finish

A high-quality result comes down to controlling each stage: start with a stable, correctly prepared substrate, mix the material thoroughly, maintain a consistent coat thickness within the recommended maximum, allow each coat to set before adding the next and once dry, sand where necessary and remove all dust before decoration.

A ready-to-use product simplifies material preparation, but good installation practice remains just as important as with any other finishing system.

Frequently asked questions

What is ready mixed plaster? Ready mixed plaster is an internal finishing material supplied as a pre-prepared paste. It’s stirred and applied straight from the tub, with no need to mix powder and water on site. PRO-570 is a polymer-modified example designed for smooth walls and ceilings before decoration.

How thick can you apply ready mixed plaster? PRO-570 has a maximum recommended thickness of 2mm per coat. For greater build, apply successive coats and allow each to set first.

How long does ready mixed plaster take to dry? At approximately +20°C, PRO-570 dries in around 2 hours and reaches its approximate hardening time at 24 hours. Actual times vary with temperature, humidity, ventilation, substrate and coat thickness.

Can you apply ready mixed plaster with a roller or spray machine? Yes. PRO-570 can be applied by steel trowel, roller or suitable spray equipment. For roller or machine application, add up to approximately 1.7% clean water per unit to adjust consistency.

Can you sand ready mixed plaster? Yes, once it’s completely dry. Sand by hand or mechanically with suitable abrasive paper or sanding cloth, then remove all dust before priming or painting.

Is ready mixed plaster the same as multi-finish plaster? No. Multi-finish is generally a dry powder mixed with water on site, whereas PRO-570 is a ready-to-use, polymer-modified paste. They can differ in thickness, drying characteristics and finishing process.

How much ready mixed plaster do I need? PRO-570 has an approximate consumption rate of 2kg/m²/mm and is supplied in 18kg units. Usage varies with substrate condition, coat thickness and technique, so allow for wastage.

PRO-570 Ready Mixed Plaster for internal finishing

PRO-570 Ready Mixed Plaster is a ready-to-use, polymer-modified finishing plaster developed to smooth internal walls and ceilings before decoration. Its factory-prepared formulation gives installers a consistent material that can be applied by trowel, roller or suitable spray equipment.

With a maximum application thickness of 2mm per coat, easy sanding once dry and compatibility with a range of common internal substrates, PRO-570 is a practical choice for professional internal finishing and refurbishment. As with any plaster system, the quality of the final finish depends on correct substrate assessment, careful preparation and application in line with the product’s technical requirements.