The other day I was asked to provide a lime lath and plaster
specification, which I did and sent it off to the contractor. A day or so later
he came back to me and asked about why I had not specified Horse hair? The
supplier he had gone to had told him that my request in the specification for
the lime mix to not contain horse hair, but ox or goat, or even yak, was wrong
and all the premixed materials they sold are 100% horse hair. While I was not surprised
by the request for the mix to contain horse hair I was surprised that it was
the supplier’s practice to supply only mixes with 100% horse hair.
Now when I started out in my career I was under the
impression that all lath plaster mixes had horse hair in them. It was an
assumption made based on what others had told me and what I had read in modern
books. However as time has passed I have been lucky enough to meet and work
with master plasterers and have used the opportunity to quiz them about it,
among other things!
My learning was greatly enhanced by me being directed to the
book ‘Plastering Plain and Decorated, a practical treatise on the art &
craft of plastering and modelling’ by William Millar, published in 1897, a
second edition in 1899 (I have the one published in 1899), a third published in
1905 and then a fourth addition which was heavily edited by George Bankart in
1927 (I also have this one to compare with the 1899), William Millar had died
some 20years before this therefore Bankart took on the task of updating the
book to suite the methods of the day. Anyone either in the trade, or like me,
just with a huge interest in these things must purchase this book.
There is a surprising difference between the 1899 edition
and the one published in 1927. I purchased the 1927 book first but was a little
disappointed as it didn’t address some of my questions I had regarding the lime
aspect of things. So I bought the 1899 and it had everything I wanted to know
about plastering at this time and the materials and recipes he would have used.
Now neither the second or fourth edition recommend the use
of horse hair but then again they do not say to not use it. The subject is
covered in both books by this sentence:
“HAIR. – Hair is used
in coarse stuff as a binding medium, and gives more cohesion and tenacity. It
is usually ox-hair (sometimes adulterated with the short hair of horses). Good
hair should be long, strong, and free from grease and other impurities.”
As can be read above its not a ringing endorsement for the
use of horse hair. When I read the book I gain the impression that horse hair
is not good to be used. For the avoidance of doubt I see the word ‘adulterated’
being defined as follows:
Now there have clearly been many walls and ceilings laid
with a lime plaster haired with horse hair, especially if the materials were bought
from some suppliers in a pre-mix tub.
Have they failed? Probably not, but that’s not the point. If there is
better hair to use, then surely it should be used? Why would you wish to use,
or specify, a material which doesn’t have all the cohesion and tenacity that a
mix with better hair would have?
I hope you have found the above interesting, you can find Millar’s
books on Amazon, Donhead published the fourth edition in 2009, if you struggle
to find the earlier editions look at forgotten books, operated by Amazon.
Many thanks for reading
James
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