Sheltercoat

Preparation

• Flush loose dust from stone surface.
• Dampen stone down several times using limewater.
• Thin sheltercoat mortar down to a thin creamy consistency with a 50/50 mixture of water/skimmed milk. This must be done no longer than one hour before it will be used otherwise the binding effect of the casein may be lost

Application

• Apply to the stone using a soft short haired brush working the sheltercoat well into the surface paying special attention to eroded areas, cracks and fissures.
• As the sheltercoated surface turns matt (as water is absorbed into the stone) work in the sheltercoat a second time with a clean dry brush. Timing is imperative - if the sheltercoat is too wet it is merely moved around the stone surface, if it is too dry it is brushed off. This second working in is comparable to the compacting of putty lime mortars as they stiffen after application. When sheltercoat is applied properly the brushstrokes should be barely visible.
• When the sheltercoat has completely dried a small brush can be used to remove any excess that may have built up in undercut areas and fine detail.
• Protect sheltercoated surfaces promptly after an area has been completed. It is essential that sheltercoat dries slowly to ensure maximum strength is obtained.
• Dampen down sheltercoated areas each day for three days after application.

Limewater

Preparation

• Draw off the limewater as required using a patent 'solo' spray pump attached to a clear polythene tube inserted 2" (50mm) into the limewater through a central hole. Alternatively the limewater can be drawn off into a portable garden spray (killaspray type).
• Wet the stone with one application of tap water prior to first application of limewater to aid its penetration.
• Ensure the limewater is water clear.
• Only apply to cool stone. Do not limewater stone that has been warmed by the sun and do not apply limewater in hot weather.

Application

• Apply a floodcoat of limewater starting at the bottom of the area to be treated, moving sideways and upwards.
• Immediately after application sponge off any access limewater from the stonework surface using a clean sponge frequently rinsed in a bucket of clean water. This will prevent white limebloom from forming.
• Whenever possible do not let the stone dry out between applications.
• Eight applications per day is likely to be maximum attainable.
• Apply a total of 40 coats or until the rate of absorption by the stone surface has been significantly reduced.

Plasters

Preparation

• Ensure area to be plastered is clean, free of dust and sound.
• Thoroughly dampen area to reduce and control suction from new plaster.
• Ensure joints are raked out or set back to a minimum 16mm depth.

Application

• Dub out hollows and depressions with as many coats as necessary. No coat to exceed 10mm. Mortar surface to be keyed.
• Apply lime plaster in three coats allowing 2 days between each coat to ensure initial shrinkage is over before application of the next coat.
• Each coat to be combed to provide a key for the succeeding coat.
• Dampen each coat prior to application of subsequent coats to reduce and control suction from new plaster.
• Final coat to be finished with a wooden float and not overworked.
• After final coat of plaster, allow plaster to cure for 1 month before application of limewash.

Limewash
Limewash is a traditional paint for decorating stonework, renders and plasters. In its raw form it is white or off-white but is often coloured with earth pigments to give colours like pink, warm grey, buff, cream and yellow. Limewash is moisture permeable and allows stonework and plasters painted with it to 'breathe'. It is made from either lime putty or slightly hydraulic lime.

Preparation

• Brush down and flush loose dust from stone/plaster surface.
• Dampen stone/plaster surface thoroughly.

Application

• Apply using a large bristle brush working the limewash well into the surface paying special attention to eroded areas, cracks and fissures.
• Apply up to four coats allowing one day curing between each coat.

Protect limewashed surfaces from premature drying as it is essential that limewash dries slowly and remains damp for at least four hours to ensure maximum strength. Limewashed surfaces may be dampened down with fine mist sprays if early drying is a problem.