Cornerstone Promix Topcoat is a high-quality, dry pre-mixed render and plaster ideal for both internal and external finishing within an appropriate render system. Offered in a light brown shade, it delivers a delicately textured appearance when finished with a plastic or wooden float or sponge. When a trowel finish is applied, it results in a smooth surface with minimal texture.
Formulated using 100% pure natural hydraulic lime, natural sands, and specially selected conservation-friendly additives, this render and plaster offer exceptional performance, making it suitable for high-traffic areas and outdoor environments. Its enhanced plasticity reduces the chances of slump, while improved adhesion ensures a lasting bond. The longer open time allows for easy application, levelling, and finishing. While it comes standard with Saint-Astier® NHL2, alternative binders can be supplied upon request.
This product is perfect for anyone seeking a natural, traditional look or a finely textured external finish. Cornerstone Promix Topcoat is recognised as one of the best external renders in its category, popular for creating a mock ashlar effect. Its conservation-friendly additives ensure that it's both functional and aesthetically appealing.
Key features
- Vapour-permeable design for better moisture management
- Mimics the feel of modern mortar
- Free from pigments to maintain colour integrity
- Easy levelling and finishing
- Superior water retention with reduced risk of slumping
- Lower chance of shrinkage cracks
- Enhanced workability for a smoother application experience
- Extended working times promote even curing and improve bond strength
Ideal for both professionals and DIY enthusiasts, Cornerstone Promix Topcoat stands out as a reliable choice for those seeking a premium external render solution.
Applications
Promix Topcoat is suitable for both indoor and outdoor use, providing strong bonding for different surfaces. It is great for external finishing render coats, such as float and sponged finishes, in a proper render system. You can use it for various projects, including conservation, renovation, and sustainable construction.
You can apply Promix Topcoat Fine as a top layer over Cornerstone Insulating Render and Cornerstone Supertherm Insulating Render.
You can apply Promix Topcoat as a top layer over Promix Coarse Basecoat or as the second coat on render carrier boards with mesh in the base layer. A 25kg bag will yield about 15 litres of lime render or plaster and cover around 5m² with a thickness of 3mm. Keep in mind that the amount you use may change depending on the surface's evenness and how much it absorbs. It is a good idea to do on-site tests for the best results for your project.
Since our kiln-dried sands are natural products, they may have slight variations in colour, texture, and shape. If colour consistency is important, we recommend using material from the same batch for each elevation.
Do not use Promix Topcoat if temperatures are below 5°C or above 30°C, or if freezing conditions are expected in the coming weeks, including wind chill. Always follow best practices for curing and protecting fresh lime renders and plasters. Protect them from poor weather conditions, such as frost, rain, direct sunlight, and drying winds.
Store the product in a covered, dry location away from moisture and frost and off the ground. If any product is left, always reseal the packaging.
Technical Information
- Materials: Natural Hydraulic Lime, Natural Sands, Additives
- Mix Ratio: 2:5, others available on request
- Binder: NHL2, others available on request
- Aggregate: 3mm down blended sand
- Work: Rendering, Plastering
- Coverage: A 25kg bag covers approx. 1.9m2 at 7mm thickness
- Yield: A 25kg bag yields approx. 15 litres
- Colours: Tan
- Use: Internal & External
- Coat: Topcoat
- Standard: BS EN 998-1: 2016
- Fire Rating: A1
Downloads
- Cornerstone Promix Topcoat FINE - Technical Data Sheet (PDF)
- Cornerstone Promix Topcoat MEDIUM - Technical Data Sheet (PDF)
- Cornerstone Promix Topcoat - Safety Datasheet (PDF)
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