Product description, performance & data overview

1. OVERVIEW

A premixed, pre-pigmented interior wall & ceiling plaster, ready to mix with water. Apply with traditional plastering skills and tools. 100% natural: all compostable.

2. SUPPLY

25Kg bags of dried plaster. Recyclable or compostable bags.

3. CLASSIC FINISHES

Smooth – Tonal – Demi-rustic – Rustic.

4. CUSTOM FINISHES

Rammed earth, colour ombre, two-tone anaglyptic, corrugated, etc.

For the complete list of custom finishes click here.

5. SUSTAINABILITY

Extremely low embodied carbon: 0.048 – 0.068 kgCO2 e/kg. (LCA stages A1-A3. Full A1 – D assessment is available in our EPD).

Product and packaging are fully compostable at all stages of lifecycle.

6. HEALTH

100% natural, zero VOCs, formaldehydes, polymers or oils. Absorbs toxins, regulates humidity. No off-gassing.

7. OTHER ESSENTIALS

Clayworks Wall Primer & Clayworks Glaze (supplied by Clayworks with all clay orders plaster for additional cost).

8. APPLICATION

We strongly recommend application by an approved Clayworks plasterer. Where not possible, follow our application guidelines.

9. COLOURS

88 Standard colours. Custom colours available on request. UV resistant. Through pigmented.

10. COMPOSITION

Unique blends of unfired clays mixed with natural minerals and pigments.

11. SUBSTRATE

Most commonly applied directly onto gypsum plasterboard, masonry, blockwork, wood fibre board & wood wool carrier board. Can be applied directly onto gypsum backing board suitably primed. Other substrates may require a backing coat. For details please also see our separate data sheet ‘Clayworks Design Details‘.

Cannot be applied directly onto wood, including plywood, MDF or OSB.

12. RESTRICTIONS ON USE

Suitable for interior walls and ceilings and fixed furniture. Appropriate for bathrooms, but not wet or shower areas. We advise against use on items that will be moved around or doors. Not suitable for floors. Clayworks supply interior waterproof finishes and exterior grade finishes where a seamless match is required.

13. COUNTRY OF ORIGIN

UK. Manufactured in Cornwall.

14. FIRE

BS 476: Part 7: 1997 Surface spread of flame: achieved Class 1.
BS 476: Part 6: 1989 + A1: 2009 Fire Propagation test: fire propagation index I = 0.5, i1 = 0.0

The results confirm that the plasters fulfil the following: UK Building Regulations: Class 0.
Class 0 is defined as: BS 476-7 Surface spread of flame Class 1, and BS 476-6 Fire propagation index test (I < 12, i1 < 6)

15. HEALTH & SAFETY

As a powdered product a dust mask should always be worn when handling the product. Non Caustic.

16. ACOUSTICS

Noise Reduction Coefficient (NRC): 0.20 – 0.25 NRC depending on backing board. Sound absorption Coefficient tests conducted in accordance with British Standard BS EN ISO 354 available.

17. MAINTENANCE

Can be wiped clean with a non-toxic cleaner when glazed. Seamless. Easily repaired. Fixtures, fittings, wall hangings as per any other plaster.

18. DRYING TIMES

2-3 hours each layer, depending on temperature & humidity.

19. IMPACT

BS EN 520 – Impact Diameter < 15mm.

20. MOISTURE BUFFER VALUE

1.28 [calculated by moisture change (g/m²) divided by relative humidity] where buffering was tested to be 9x that of painted plasterboard. (University of Bath figures).

21. LIGHT REFLECTIVE VALUE

Tested to BS.8493: 2008+A1: 2010. Data available on request.

22. DATA COMPARISON – SMOOTH/TONAL – DEMI-RUSTIC – RUSTIC

SMOOTH / TONAL  DEMI-RUSTIC  RUSTIC 
Coverage per 25kg bag  7 – 8 sqm  2.7 sqm  1.25 sqm 
Thickness 2mm 5-6mm 10mm
Moisture absorption value     1.28 1.4 1.4
Density: loose powder 1137.581 (low g/L) –1573.407 (high g/L) 1132.042 (low g/L) – 1506.464 (high g/L) – 1240.536 (low g/L)– 1581.256 (high g/L)
Density: Applied kg/m3 1270   1682 1536
Density: Applied kg/m²   2.5  10.1 15.4
Impact BS EN 520     Impact Diameter <15mm Impact Diameter <15mm Impact Diameter <15mm
Thermal conductivity     0.84 W/mK 0.97 W/mK 0.97 W/mK
VOCs zero zero zero
Acoustic absorption  properties – sound absorption coefficient 0.10 0.20 0.25

23. TOOLS FOR THE JOB

The tools needed to apply all Clayworks clay plasters are essentially the same  as for any other plastering job: 

•  Hawk 

•  Laying on trowel 

•  Detail trowels 

•  Plastic polishing trowel 

•  Fine mist sprayer 

•  Clean buckets for mixing 

•  Clean water 

•  Hand held plasterer’s whisk 

•  Sponges 

•  Masking tape 

•  Protective sheeting 

•  Appropriate respiratory protection. 

•  Specialist Japanese rectangular trowels (essential for polishing/finishing) 

•  Plastic trowels (for polishing/application of glaze) For large projects, spray 

application is also possible. 

24. HANGING PICTURES

Observe the same protocol as for conventional plaster using picture hooks or screws. 

25. REPAIRS

Any damage caused to a Clayworks surface will be inconspicuous due to their through bodied colouring. Chips, divots and scrateches can be simply repaired through the addition of a small quantity of colour matched clay plaster, trowelling and repplication of the protective glaze. 

26. FUNDAMENTAL MATERIAL SAFETY

Clayworks clay plasters contain no asbestos, lead, PCBs or mercury. They contribute to toxic material reduction targets because they contain no perfluorinated compounds (PFCs), no flame retardants or phthalates (plasticisers), or isocyanate based polyurethanes. Clayworks clay plasters contain no synthetic additions and emit zero VOCs or formaldehydes. There is evidence to suggest they may proactively mitigate the presence of formaldehydes in a space. 

27. THERMAL PROPERIES OF CLAYWORKS CLAY PLASTERS

According to research by Tom Morton et al, the physical mass of clay plaster (20.6 kg/m²) is 2.5 times that of gypsum plaster (8kg/m²). 

Data sheet: July 2021