Difference between revisions of "Lime Plaster"
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==Tools required== | ==Tools required== | ||
| − | * ''' | + | * '''PPE''' - Eye protection and gloves as a minimum. Lime in the eyes is very dangersous and happens easily when handling plaster at any stage of the process. Gloves will protect our hand from the caustic drying effect of the lime. Overalls will obviously protect the rest of you and your clothes. A hard hat would be a good idea and essential on most building sites inside and out. |
| − | * '''Hawk''' - wood or plastic to carry plaster to the wall and keep it 'fat' | + | * '''Buckets/Trugs''' - if required for water and to mix/carry mortar, harling coat slurry or finish coat. |
| − | * '''Plasterers Trowel''' - | + | * '''Harling Trowel''' - if required for a base splatter coat. |
| − | * '''Wood Float''' - to smooth the surface and remove any tooling mark, also | + | * '''Bucket Trowel''' - to put plaster on the hawk. |
| − | * '''Devil Float''' - a float with a couple of lath nails driven through so they just protrude to provide a fine key | + | * '''Water Sprayer''' - to damp the surface to control suction and to keep mortar damp during ealy parts of cure (a couple of days at least). Various sizes depending on areas to be covered, portability and access. Might need a hose if a lot of water is required (e.g. dry brick walls). |
| − | * '''Firm Sponge''' - used on the skim to finish the surface | + | * '''Hawk''' - wood or plastic to carry plaster to the wall and to knock it up to keep it 'fat'. |
| + | * '''Plasterers Trowel''' - 9"x3" upwards, start smaller when you are learning. Used to push plaster (firmly) on to the wall and to finish the skim coat if a very smooth finish is required. Stainless flexible blades are easier to use and longer lasting than stiff carbon steel although much more expensive. A 'Venetian' trowel is easier to use on uneven surfaces as it has a thin blade and the corners are rounded and edges beveled so do not catch as much as a standard trowel. | ||
| + | * '''Scratcher''' - 6-8 pins in a handle (like a coarse comb) to gently score the surface to provide a key in the scratch coat for the levelling coat. | ||
| + | * '''Small Trowel''' - approx 8" or could be a bit smaller for detailed work/smaller areas/restricted spaces. | ||
| + | * '''Japansese Trowel''' - approx 8" (alternative to small trowel), if doing a lot of detailed work around windows, architraves etc., as it has triangular points up front and square ends at the back. | ||
| + | * '''Wood Float''' - to smooth the surface and remove any tooling mark, also raises the texture slightly. | ||
| + | * '''Devil Float''' - a float with a couple of lath nails driven through so they just protrude to provide a fine key (can use the wood float with a couple of screws through the front corners which can be removed of unscrewed out of the way) | ||
| + | * '''Firm Sponge''' - used on the skim to finish the surface if an open texture is required (better moisture transmission). | ||
==YouTube Videos== | ==YouTube Videos== | ||
Revision as of 00:53, 5 November 2019
Contents
Internal Lime Plaster
Typically three coats of varying consistencies of lime mortar and plaster but can be four if a harling coat is also used (where suction is very poor)and even five if the wall is uneven enough to require much dubbing out. All coats are a mix of sharp sand and quicklime mixed hot with the exception of the finishing coats which can use fine sand and lime putty for a finer finish (i.e. 3:1 is three parts sharp sand and one part quick lime or for a finish coat 1 part fine sand to 1 part mature lime putty)
- A thin 'harling' (or thrown) coat to provide a key and control suction (particularly on cob or brick) or to provide a key on impervious surfaces with poor suction - optional (3:1 made sloppy with extra water)
- A dubbing out coat to fill any deep depressions where a flat final finish is required - optional (3:1 hair/fibre optional)
- A scratch coat, the body of the plaster, about 10-15 mm thick to roughly flatten the surface, keyed by scratching with a comb to provide a grip for the float coat. (3:1 haired)
- A float coat to form a flat base, lightly scratched, for the final finish or top coat (3:1 unhaired).
- The top coat or finishing skim, much finer mix applied in two layers (2:1, 3:2 or 1:1 depending how fine a finish is required using finer silica sand, lime sand or even chalk dust)
External Lime Plaster or Render
Similar to above, tends to be less fine finish and depending on weather resistance/water control may include a pozzolan in the scratch coat and float coat to give an earlier (chemical) set and also reduce water absorbtion/transmission.
Tools required
- PPE - Eye protection and gloves as a minimum. Lime in the eyes is very dangersous and happens easily when handling plaster at any stage of the process. Gloves will protect our hand from the caustic drying effect of the lime. Overalls will obviously protect the rest of you and your clothes. A hard hat would be a good idea and essential on most building sites inside and out.
- Buckets/Trugs - if required for water and to mix/carry mortar, harling coat slurry or finish coat.
- Harling Trowel - if required for a base splatter coat.
- Bucket Trowel - to put plaster on the hawk.
- Water Sprayer - to damp the surface to control suction and to keep mortar damp during ealy parts of cure (a couple of days at least). Various sizes depending on areas to be covered, portability and access. Might need a hose if a lot of water is required (e.g. dry brick walls).
- Hawk - wood or plastic to carry plaster to the wall and to knock it up to keep it 'fat'.
- Plasterers Trowel - 9"x3" upwards, start smaller when you are learning. Used to push plaster (firmly) on to the wall and to finish the skim coat if a very smooth finish is required. Stainless flexible blades are easier to use and longer lasting than stiff carbon steel although much more expensive. A 'Venetian' trowel is easier to use on uneven surfaces as it has a thin blade and the corners are rounded and edges beveled so do not catch as much as a standard trowel.
- Scratcher - 6-8 pins in a handle (like a coarse comb) to gently score the surface to provide a key in the scratch coat for the levelling coat.
- Small Trowel - approx 8" or could be a bit smaller for detailed work/smaller areas/restricted spaces.
- Japansese Trowel - approx 8" (alternative to small trowel), if doing a lot of detailed work around windows, architraves etc., as it has triangular points up front and square ends at the back.
- Wood Float - to smooth the surface and remove any tooling mark, also raises the texture slightly.
- Devil Float - a float with a couple of lath nails driven through so they just protrude to provide a fine key (can use the wood float with a couple of screws through the front corners which can be removed of unscrewed out of the way)
- Firm Sponge - used on the skim to finish the surface if an open texture is required (better moisture transmission).
YouTube Videos
How to lime plaster an internal solid wall by Artisan Fine Architectural Plasterwork
Lime Plaster Application Guide by Ty Mawr
Lime Rendering and Lime Plastering Step By Step by Sed Edwards with John Edwards Lime
