Solid plastered surfaces conservation

carry out written and verbal instructions

select and use hand tools to remove existing solid plasterwork

to include:

• lump hammer

• bolster chisel

• cold chisel

• scutch hammer

• mechanical stripping tool (kango hammer)

cut away existing solid plasterwork

record and survey plasterwork condition

demonstrate how to:

• remove timber lathing

• fix timber lathing

• clean down backgrounds

• remove debris from work area

• protect existing plasterwork from damage when carrying out the works

demonstrate how to:

• provide adequate key on various backgrounds

• apply and finish internal and external plasterwork

• produce in situ mouldings

• repair in situ mouldings

• provide aftercare to prevent damage from rapid drying out or freezing

• rake out and repair cracks

select and use the resources required to stabilise plasterwork  

to include:

• limes

• cements including natural cement

• timber

• types of lathing

• fixings for lathing

• sands and other aggregates

• proprietary lime renders

• proprietary lime bonding materials

• natural materials (hair/wattle/ reeds)

• additives: accelerators/air entrainers/retarders/water

demonstrate methods of securing loose plaster from the face using mechanical fixings or insertion of grouting materials

demonstrate methods of securing loose areas of lath and plaster ceilings

to include:

from above or below where laths are damaged by dry rot or insects

where plaster keys have been damaged above

prepare a mould for cement casting

gauge and mix casting materials

to include:

• prepare mould for casting (wet and semi dry method)

• select lime/cements/sands/clean water for mixing

• gauge and mix casting materials

• place and compact mixed materials

• finish cast produced

• cure cast for up to 1 week keep damp

• place and compact mixed materials in mould

explain the purpose of using like for like materials

explain the purpose of curing and mist spraying of solid backgrounds

select material which is of the type appropriate to period of work

to include:

• plasters

• cements

• sand and other aggregates

• limes

• hair

• fixings

• additives

explain the purpose of curing Ordinary Portland Cement (OPC) casts

to include:

• moisture must be in place to allow for continued hydration to take place

• the setting action must continue between the OPC and moisturiser for up to 7 days

• this method of curing ensures a hardened cast

• the cast object can be immersed in water

• covered with plastic sheeting

• covered with hessian and kept damp

explain the difference between wet casting and semi-dry casting

• The Wet method of casting is where there are a number of moulds to cast but are not on a time scale, so with this method the mix is made up to a slurry and poured into the moulds. After two or three days the casts are removed and allowed to cure. This is sometimes called flood moulding. It must be remembered that sand and cement mix is slow setting.

• The Semi-Dry method is used where there is a short supply of moulds so the mix is gauged with just enough water to bind the aggregate and cement together. This mix is then tamped into the mould in layers. When completed the mould is turned upside down and the cast is removed. This system is the same as the one used on a bench with the bucket and spade. The cast is cured in the same way.

explain how to run mouldings in-situ

explain how to run down short breaks

explain how to cut and plant short breaks

explain how to finish moulding/mitres using joint rules and busks

explain how to validate ways in which the work should be carried out

explain the following roles and responsibilities:

• the client

• the principal designer

• the conservation architect

• the main contractor