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It’s Just a Wall… Hand Plastering
for Health and Beauty
By
Thomas Hirsch
In
the eight or so years since I started to work with clay/ earthen plasters,
I have always had eager and enthusiastic responses from crewmembers,
owners and curious hands-on types. Never
in my twenty plus years in the building business have I had that kind of
reaction when it comes to drywall—the contemporary approach to indoor
wall coverings in the industrialized world.
What is so
satisfying? Is it working
with raw, local materials that are unrefined and relatively inexpensive?
Is it a reconnection with our ancestral roots where everyone built
their own dwelling and hand plastered it with whatever was at hand?
Is it the discovery of unlimited textures, colors, pigments and
molded shapes like arches, curves and niches?
Is it the feeling of independence that occurs when doing this work for
oneself… or maybe the feeling of interdependence when done within a
community? Is it because it
is fun to do and beautiful to the eye?
Perhaps it is all of these things that generates such fondness.
Notice the
experience you have of seeing hand rendered wall finishes with
imperfections and gentle undulations (or not so gentle in the case of
heavy textures) that play with light and color.
Contrast this experience with that of a typical drywall
installation. These surfaces
are usually a smooth, slick attempt at a perfect wall or ceiling.
They can appear lifeless, flat, “monotone”, cold and
unwelcoming. While writing
this I notice that our painted concrete block basement walls have more
character.
The plaster
verses drywall debate continues in the areas of health, indoor air quality
and environmental impacts. Drywall
(sheetrock) is comprised predominantly of gypsum, a mined earth
mineral that is relatively abundant.
As a pure substance it makes a fine interior plaster.
But the mining, manufacturing and transportation of gypsum products
represent substantial total embodied energy consumption.
Sustainability is questionable.
Inks from recycled newsprint that comprise the drywall paper as
well as the adhesives and other additives that are sometimes included for
moist0ure and fire resistant wallboards can be a significant source of
volatile organic compounds (VOC’s) that off gas into the indoor air.
This problem is often exacerbated by the use typical over the
counter synthetic paints and premixed drywall compounds which are
chemically treated with biocides, preservatives and other questionable
additives.
Read the Material Safety Data Sheets on these products and you’ll see
what I mean. The surface area of walls and ceilings with this sort of
treatment is typically the majority of a house or workplace, thus a major
player in the toxic loading of an indoor environment.
If you have recently installed drywall, there are specially
formulated paints available that seal and prevent the off gassing of
VOC’s. There are also
anecdotal references in the literature regarding the use of potentially
radioactive tailings- a mining byproduct- in the manufacture of gypsum
wallboard. One has to
be equipped with a Geiger counter to test for this type of radiation.
Drywall
scraps from new construction constitutes a significant volume of waste
that is usually land filled. Drywall
recyclers do exist in some larger metropolitan areas.
The plastering debris from our natural mixes are recycled into the
yard or the next batch of plaster.
Natural
plasters are composed of clay, gypsum, lime, sand, fibers such as chopped
straw or animal hair, and additives like wheat flour paste, casein (from
milk) or white glue, natural vegetable oils and mineral pigments.
Many of these ingredients are readily available and recipes abound
in the Natural Building literature. These plasters possess qualities that
insure good indoor air quality such as diffusion, thermal conductivity
(thermal mass), hygroscopicity (the ability of a material to absorb and
release moisture), electrically neutral (i.e., no static electric
buildup), and non-radioactive (hopefully!).
Essentially what all of this means is that the entire wall and
ceiling area that is composed of such materials have the ability to absorb
and release moisture and heat, thus helping to regulate humidity and
temperature within a dwelling. Diffusion qualities allow these surfaces to
actually filter the air through the micro capillary pores present in such
material. Unpainted plasters or breathable natural paints will preserve
these qualities, while synthetic paints and finishes will diminish or
eliminate them. Natural
plasters are an integral part of the breathing wall system explained in a
previous HGJ article. Elaborate
research on these building science topics have been carried out by the Bau-Biologie
Institutes in Europe over the last thirty years.
A word should
be added here about cement- based plasters.
They are often revered for their hardness and durability.
However, this comes with a sacrifice of vapor permeability.
If one chooses to use a cement- based stucco/plaster for the
exterior finish, then one must use an interior finish with similar
permeability ratings. Research
has shown that the application of cement plasters to centuries-old adobe
structures in the southwest U.S., and cob structures in the United
Kingdom, have led to failures in a relatively short time.
Water vapor that traveled unimpeded through these walls for
centuries now condensed on the cold impermeable surface of the new cement
plaster. This moisture
collects over time and causes building damage. Similarly, straw bale structures skinned with an
earthen/clay/lime plaster show no degradation, whereas the cement-based
plasters did. We must also
remember the detrimental environmental impact of cement manufacturing.
The biggest
drawback to plastering is the cost. Materials
are quite inexpensive but labor costs are high.
Hand plastering can cost three to four times as much as drywall
systems. In my view, the
added benefits to indoor air quality, the diminished environmental impact,
and the greatly enhanced aesthetics are well worth the extra expense.
I confess
that those of us in the craftsman/natural home building movement may have
become snobbish about not building and living in drywall boxes.
It is simply not satisfying. Hand
plastering is great fun, has unlimited creative potential and the result
is beautiful. And of course,
using local materials has a far less detrimental impact on the earth.
In fact, I think the earth, as well as we in relation to her, is
healed by using her gifts in these ways.
It is a physical process of transformation that translates into a
physical/spiritual entity that shelters us, nurtures us and protects us as
only our mother earth can.
While
plastering one day I began to ponder the thousands of grains of sand in my
mix. How far and long have they traveled to become part of this
wall? What volumes and
what vibrations they could speak! Crystalline
magic was working its spell.
RESOURCES
Bioshield
Paint Co., Santa Fe, NM (800)
621-2591, www.bioshieldpaint.com
Clay paints
The
Black Range Lodge/Natural Building Resources, Kingston, NM (505) 895-5652,
www.strawbalecentral.com
Videos and books on natural building and natural plasters
Building
for Health Materials Center, Carbondale, CO (800) 292-4838, www.buildingforhealth.com
Plastering products, including natural pigments, dry clays, lime putty
Designed
Finishes, Boise, ID (208)
377-1994, www.designedfinishes.com
Natural earth pigments, lime putty, lime wash
National
Gypsum, Charlotte, NC (800)
628-4662, www.national-gypsum.com
Gypsum plaster
National
Lime Association, Arlington, VA (703)
243-5463, www.lime.org Publications on
lime plastering
U.S.
Gypsum, Chicago, IL (800)
950-3839, www.usg.com Gypsum plaster
International
Institute for Bau-Biologie and Ecologie, Clearwater, FL
(727) 461-4371 www.baubiologieusa.com
Correspondence courses, seminars, consultation
FURTHER
READING
The
Natural Plasters Book: Earth Gypsum Plasters for Natural Homes, Chiras
& Guelberth, New Society Publishers, 2002.
Prescriptions
for a Healthy House, Baker-Laporte, Banta and Eliot, New Society
Publishers, 2001.
The
Art of Natural Building, Kennedy, Smith and Wonek, New Society
Publishers, 2002.
Mooseprints,
Robert Laporte, self-published
Harmony
Home Construction, LLC.
8122 Barney Road
Traverse City,
Michigan 49684
Ph: 1-877-45-GREEN Fx: 231-932-9193
info@harmonyhomeconstruction.com
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