The document discusses the decline of traditional lime plastering skills due to modern gypsum plasters. It notes the need for more skilled plasterers who can work with lime and perform decorative plastering. While lime plastering skills are becoming rarer, the document argues that lime plastering is not too difficult to learn and that with basic understanding and practice, most plasterers can produce reasonable lime plastering. It provides guidance on appropriate lime materials and application techniques for traditional plastering.

2. The promotion of modern gypsum-based
plasters has led to the almost complete demise
of lime plastering, and of many of the traditional
skills associated with the craft. This has been
exacerbated by the plastering trade being
divided into flat and decorative work, with new
'fibrous plasterwork' being made in workshops.
Many youngsters entering the trade are now
just taught the basic skills to enable them to
stick up plasterboard and skim plaster onto it.
We are told that it is all down to 'supply and
demand'; if this is the case, those of us involved
in work on old buildings need to be more
demanding.

5. There is a real need for skilled plasterers who
can plaster with lime, and also turn their hands
to repairing and reinstating dado and cornice
mouldings in situ. The current training system
works against anyone gaining this set of skills.

7. An article like this cannot resolve this skills
shortage, nor attempt to even describe the range of
skills that a traditional plasterer should have.
There are, however, some general principles which
anyone involved with lime plastering should be
aware of. Sadly there are too many cases of lime
plasters failing because the people who have
specified the work or the people carrying out the
work don't have adequate knowledge or
experience.

10. THE RIGHT
MATERIALS?Most people using lime in old buildings have a vague
understanding of the benefits of a 'breathing' mortar or
plaster, but if they perceive that lime is too difficult to
use they may decide not to bother with it. We need to
make it clear that the revival of the use of lime is not
some 'airy fairy' idea dreamt up by a bunch of idealists.
On the contrary, it is driven by the realisation that
buildings are suffering because they have been coated
with inappropriate materials, and the people living in
them may be less healthy as a result. There is
compelling evidence that modern gypsum plasters
encourage condensation and consequent mould growth
if used on walls that are supposed to 'breathe'. We are
beginning to see a revival in the use of lime plasters and
we need to encourage a revival of the skills required to

13. Having bemoaned the lack of proper training for
anyone wanting to learn traditional plastering
skills, it has to be said that lime plastering is not
rocket science. With a basic understanding and
a willingness to learn, most plasterers can pick
up the skills required to produce a reasonable
job in a few days. This is not the same as the
skill required to repair plaster in a fine quality
country house, or the experience required to
match a range of historic finishes, but these
things come with time, and we can hope that as
more plasterers learn to use lime they will be
inspired to develop their skills and
understanding further.

15. There are two characteristics that differentiate
lime plasters from modern plastering materials.
The first is that they set slowly by absorbing
carbon dioxide from the air, in the presence of
moisture. The second is that they will shrink as
they dry.

17. Although hydraulic limes, which set
more quickly than white/fat limes, are
occasionally used for plastering in
damp conditions, they are less
flexible and breathable than the latter,
and their use internally should
generally be avoided. All the evidence
on old buildings and in written
documentation indicates that for
centuries, if not millennia, plasterers
have chosen to use white/fat limes for
internal plastering.

19. There is some debate about whether we really need to
use traditionally slaked lime putty, or if bags of dry
hydrated white lime from the builders' merchant are
just as good. Although chemically they are the same
(both are calcium hydroxide), a traditionally slaked
lime, which has been matured for three months, will
have broken down into much smaller particles and
started to form crystal chains. This gives it better
adhesive qualities, helping it to grip the wall more
tenaciously. The difference seems to be in the maturing
process; so if recently hydrated lime from a fresh bag is
left to soak in water for three months, it should be as
good as a traditionally slaked and matured lime.
However, in practice most of us find it is easier to buy
the matured stuff from a specialist supplier.

21. Phone :+44 1235 434300
Email: info@limetec.co.uk
Address: Limetec – LMR
Traditional
126 Olympic Avenue
Milton Park
Abingdon
OX14 4SA
United Kingdom
Website: