ATLAS CERPLAST QUARTZ TOP COAT PRIMER WHITE 25KG
ATLAS CERPLAST QUARTZ TOP COAT PRIMER WHITE 25KG
A quartz key coat decides whether a thin coat render grips the wall or slides on it. Cerplast is the Atlas answer: a ready-to-use acrylic mass filled with quartz flour, rolled or brushed over a cured base-coat so the finish has something rough and evenly absorbent to bite into.
What a Quartz Key Coat Does Between Base-coat and Finish
Four things make the case for this key coat, and only one of them is adhesion.
Grip. The aggregate develops the effective surface between the two layers and leaves a deliberately rough film — what the wet render keys into, and what stops it slipping as it is pulled up.
Even suction. Cerplast limits how fast the substrate pulls water out of fresh render, so a patchy wall stops behaving like several walls at once.
A chemical barrier. The dried film is described as a barrier between substrate and render that limits colour bleed from below and the stains it produces on the finished surface. Under a light finish on a repaired or discoloured wall, that is usually the property which earns the money.
A named component, not an approximate match. Cerplast is listed by name in both product sheets of a UK system certificate, so a specification can point at the document rather than at a description.
Adhesion to concrete is stated twice in the same technical sheet, and not identically: the properties paragraph gives min. 1.0 MPa, the technical data table gives > 1.0 MPa. At least 1.0 MPa holds either way, and that is the figure to put in a specification.
Cerplast in Numbers — the Manufacturer's Own Figures
Property | Documented value |
Composition | Acrylic resins and quartz flour |
Density, ready to use | Approx. 1.5 g/cm³ |
Adhesion to concrete | At least 1.0 MPa |
Consumption | 0.3 kg/m² on average |
Drying before rendering | 4 to 6 hours |
Working temperature | +5 °C to +30 °C |
Application | Roller, brush or machine |
Pack sizes | 5, 10, 15 and 25 kg buckets |
Shelf life | 12 months from production date |
Colour | White base, seven DEKO M shades, SAH tinting |
Rate inside BBA 13/5018 | 0.25 to 0.35 kg/m², system scope |
Coverage and How Many Buckets a Wall Takes
Consumption is declared per square metre and tubs are bought whole, so the arithmetic is worth doing once.
At the average rate of 0.3 kg/m²: 25 ÷ 0.3 = about 83 m² from one bucket.
At the upper rate the BBA certificate applies to key coats inside its build-up, 0.35 kg/m²: 25 ÷ 0.35 = about 71 m².
Order against the higher rate and the wall never runs short: 100 m² works out at 100 ÷ 71 = 1.4, so two tubs, with the balance absorbed by reveals and rough patches. On a smooth, well-prepared base-coat the average rate is realistic and one tub covers most of a semi-detached gable.
Colour: One White Base and Seven Matched Shades
Cerplast leaves the factory white, which is why it works as a barrier under pale finishes, and we tint it at the counter while an order is made up. Beyond white it is made in seven shades matched to the DEKO M mosaic renders:
White, brown, clinker, graphite, sand, grey and coffee — the shade for a particular DEKO M pattern is printed in that render's own technical sheet.
Tinted to the SAH Colours of Renders and Paints: 400 shades on the July 2023 English sheet, 418 on the May 2025 Polish one. Specify against 400 and the shade exists in either.
