A plain faced cast plaster ceiling (or wall) is formed from flat rectangular panels of fibrous plaster work.
These panels are made with a perimeter rebate around their outer edge to enable flat scrimmed joints to be formed which will not crack or distort where adjacent panels abut one another.
Panels are made to a size that will facilitate safe and efficient handling, transport, storage and installation.
Individual panels are formed on a dedicated glass top bench in a workshop. This gives the face of the casts a flat, smooth finish which is superior to hand-trowelled work in terms of appearance and accuracy.
Timber laths secured in splashed plaster and scrim reverse side to the face allow fixing by adhesives, mechanical means, wads of plaster-soaked scrim and wires. Types of fixing used to secure the panels will depend on backgrounds, but wherever possible two types of fixings should be used.
Advantages and Uses
Traditionally, plain faced fibrous plaster was used in the highest class of work. Lightweight yet strong when dry, accurate, secure, long-lasting and very fireproof which gave rise to its use as a decorative fireproof protection to timber and steel, resisting flame and heat.
In today’s fast-track construction plain faced panels are seldom used as savings can be achieved by using fireline plasterboard or pre-formed modern day ceiling and wall partitions.
Glass reinforced gypsum (GRG) is also used which is formed from alpha-grade plasters reinforced with glassfibre sheets or strands. GRG can be made to a designers specification using hand layup methods from moulds in a similar manner to fibrous plaster work.
Plain faced work still has its uses in restoration work or where a client understands the benefits and is prepared to incur the additional costs required to achieve this type of finish.
Plain faced work or GRG are versatile in that a craftsman using moulds made in the workshop can produce virtually any shape required by designers, specifiers or clients simply using casting plaster and mould making materials always available in the workshop.