Basecoat Plaster (with Fibres)
Non-hydraulic lime putty basecoat plaster produced from 6 month mature Chalk lime putty mixed with washed medium limestone sands at a ratio of 1:2.5 by volume.
Two versions are available: SPH5 and SPH8. Fibres are added at a rate equivalent to 2.5 kgs animal hair per tonne (SPH5). SPH8 with additional fibres (equivalent to 4 kgs animal hair per tonne) must be used for the ‘pricking-up’ coat to ceiling laths.
Additional information
For internal plaster base-coats (dubbing, pricking-up/scratch, and float) where a soft, porous, permeable plaster is appropriate. Find technical advice on our Advice page on:
Internal Plain Lime Plastering
Hair/fibre reinforcement in basecoat plasters
The use of Haired Basecoat Plaster & Fine Finish
Environmental Considerations
Lime Putty plaster is an environmentally sustainable product.
Usage/Purpose
For internal plaster base-coats (dubbing, pricking-up/scratch, and float) where a soft, porous, permeable plaster is appropriate. Base-coat plasters are applied in maximum 10mm thick coats and finished with Fine Finish Plaster (RJ 2.04) and decorated with a permeable paint such as Limewash (RJ 3.01/3.02), or Soft or Casein Distemper (RJ 4.01/RJ4.02). Do not apply Oil-Bound Distemper (RJ 4.03) to new lime plaster. Do not use below a temperature of 5°C or above 25°C. Do not use if there is risk of frost.
Coverage
Approx 50 m2/ tonne at 10mm thickness
Shelf Life
Unlimited. Standard basecoat renders now contain fibres and sisal, as there is no issue associated with deterioration of reinforcement. Animal hair deteriorates rapidly in wet plaster and hair reinforced plasters must be used immediately, preferably adding the hair on site immediately before use. Lime putty renders stiffen during storage, but can be plasticised by thorough re-mixing normally without the addition of water. The render will begin to set if a pozzolan is added. Do not remix pozzolan gauged render.
Observations
Tradesmen familiar with the use of lime putty plaster, and with experience of its successful use should be employed. Lime putty plasters do not perform as gypsum, hydraulic lime or cement based materials and set only by reaction with atmospheric carbon dioxide in the presence of moisture. This ‘carbonation’ is a slow process and control of the drying and curing process by mist-spraying, ‘tending’ and protecting is crucial to long-term performance. Protections are essential.
Application
Base-coat plasters are applied in maximum 10mm thick coats and finished with Fine Finish Plaster (RJ 2.04) and decorated with a permeable paint such as Limewash (RJ 3.01/3.02), or Soft or Casein Distemper (RJ 4.01/RJ4.02). Do not apply Oil-Bound Distemper (RJ 4.03) to new lime plaster. Lime putty plasters do not perform as gypsum, hydraulic lime or cement based materials and set only by reaction with atmospheric carbon dioxide in the presence of moisture. This ‘carbonation’ is a slow process and control of the drying and curing process by mist-spraying, ‘tending’ and protecting is crucial to long-term performance. Protections are essential. Do not use below a temperature of 5°C or above 25°C. Do not use if there is risk of frost.
Availability
Heat-sealed bags (c.25kgs, 40/tonne); 15 litre tubs (c.28kgs, 36/tonne) Bulk bags (c. 1 tonne). Standard mixes are supplied ex Stock.
