Description
Ceresit CT16 is a quartz key coat: a ready-to-use priming paint with fine mineral aggregate that goes on as the last coat before a thin-coat render. It lowers the suction of the background, leaves a rough, scratch-resistant surface for the render to grip, and evens out the colour underneath. The 10 litre container holds about 15 kg and covers roughly 29 to 50 m² in one coat. Ceresit also sells it under the trade name CT 16 Quarz Contact, and Renders World stocks it in the 10 litre container.
What Ceresit CT16 Does to a Background
- Slows the background down. Priming with CT 16 considerably decreases the absorption of the background, so the render does not dry out too fast.
- Gives the render a key. The fine aggregate makes the primed surface rough and scratch resistant, and the larger surface area raises the adhesion of renders, putties and paints.
- Prevents patchy colour. Its strong covering power makes the background uniform, which stops stains forming on coloured acrylic, mineral, silicate-silicone, silicone and elastomeric renders.
- Waterproof and vapour permeable. Ceresit describes the coat as both, with high opacity.
- Ready to use. Stir, then apply with a roller or brush; it is never diluted.
Ceresit recommends CT 16 for priming the reinforced layer in Ceresit Ceretherm insulation systems and for traditional renders. It also goes onto chipboard, plasterboard, gypsum plaster, all types of concrete and strong paint coats.
Technical Data
| Property | Ceresit CT16 |
|---|---|
| Base | Water dispersion of synthetic resins with mineral fillers |
| Density | approx. 1.5 kg/dm³ |
| Consumption | 0.2–0.35 l/m² (0.3–0.5 kg/m²), depending on the smoothness and absorbency of the background |
| Drying time | approx. 3 hours |
| Application conditions | +5 °C to +25 °C, air and background; humidity below 80 % |
| Dilution | none — do not dilute |
| Tools | roller or brush, one even coat |
| Shelf life | up to 12 months from production, cool, in undamaged packaging, protected from frost and direct sunlight |
Ceresit's values are measured at +23 °C and 50 % relative humidity. In other conditions drying runs faster or slower.
How Far One 10 Litre Container Goes
At 0.2 to 0.35 litres per m², one 10 litre container covers about 29 m² on a rough, absorbent background and up to 50 m² on a smooth one, in one coat. Measured by weight the result is the same: about 15 kg at 0.3 to 0.5 kg per m² gives 30 to 50 m².
| Wall area | Smooth background (0.2 l/m²) | Rough or absorbent background (0.35 l/m²) |
|---|---|---|
| 25 m² | 5 l — 1 container | 8.75 l — 1 container |
| 50 m² | 10 l — 1 container | 17.5 l — 2 containers |
| 100 m² | 20 l — 2 containers | 35 l — 4 containers |
Getting the Background Right First
Ceresit CT16 needs a background that is:
- Smooth, even and dry.
- Free of grease, bitumen, dust and anything else that weakens adhesion.
- Cleared of dirt, weak coats and old adhesive or lime paint. Washing equipment with a cleaning agent shifts stubborn dirt.
- Repaired, with gaps or defects in old render filled before priming.
Very absorbent backgrounds — gypsum plaster, chipboard, plasterboard that is not impregnated — are primed first with Ceresit CT 17, a penetrating primer, and left for about 2 hours. CT 16 goes on after that. Our guide to preparing a wall before rendering works through the common UK backgrounds, and rendering on different substrates covers the awkward ones.
How to Apply Ceresit CT16
- Stir the container. Mix the contents well before use, and do not add water.
- Use clean tools. Do not use rusty containers or rusty tools.
- Apply one even coat with a roller or brush, between +5 °C and +25 °C and below 80 % humidity.
- Match the colour. Under a thin-coat render, Ceresit recommends CT 16 in a colour close to the render, so the background does not show through.
- Let it dry for about 3 hours before the render goes on.
- Clean up with water. Wash tools and fresh splashes straight away. Rinse eyes with water if they are splashed, and see a doctor.
The quartz primer application guide walks through the same steps on an insulated wall.
Ceretherm Systems That Include CT 16
Ceresit CT16 is a component of these Ceresit Ceretherm insulation systems, each with its own European Technical Assessment:
| Ceretherm system | Assessment | Declaration of Performance |
|---|---|---|
| Popular | ETA 08/0309 | DoP 00426 |
| Classic | ETA 09/0014 | DoP 00420 |
| Visage | ETA 11/0395 | DoP 00431 |
| Wool Classic | ETA 09/0026 | DoP 00424 |
| Universal EPS | ETA 13/0535 | DoP 00433 |
| Universal XPS | ETA 13/0807 | DoP 00434 |
| Universal MW | ETA 14/0127 | DoP 00435 |
The assessments cover the complete build-up, so specify CT 16 within the system you are installing.
Where Ceresit CT16 Sits Among the Primers
A penetrating primer and a quartz key coat do different jobs, and on many walls the two go on one after the other:
- Ceresit CT 17 soaks in and consolidates a weak, absorbent wall.
- Ceresit CT16 sits on the surface and gives the render something to grip.
The other quartz key coat on our shelf is Atlas Cerplast, made for Atlas thin-coat renders. Pick the key coat that belongs to the render system you are using. CT 16 is also the coat Ceresit puts under Ceresit CT 177 mosaic render. The full Renders World range of render primers, and our article on choosing a primer under silicone render, help you match primer to finish, and the Renders World counter can advise on the build-up.
Frequently Asked Questions
How many containers does a 100 m² elevation take?
Two on a smooth background (0.2 l/m² = 20 litres) and four on a rough or absorbent one (0.35 l/m² = 35 litres). Most walls fall in between, so measure the area and order for the rougher end if in doubt.
Can it be thinned to go further?
No. Ceresit CT 16 is used as supplied and must not be diluted.
Does it replace a penetrating primer?
No. On absorbent backgrounds, prime first with Ceresit CT 17, wait about 2 hours, then apply CT 16. CT 16 is the key coat that goes directly under the render.
Is Quarz Contact the same product?
Yes. Ceresit sells CT 16 under the trade name CT 16 Quarz Contact.
How long before I can render?
About 3 hours at +23 °C and 50 % humidity; in other conditions it dries faster or slower.
Technical Documentation