Clay plaster

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Contents 1 Material analysis 1.1 Traditional uses 1.2 Emerging uses / trends 1.3 Finish and aesthetic qualities 1.4 Cost analysis 2 Material properties 2.1 Primary structural use 2.2 Material performance 2.3 Acoustic property 2.4 Manufacturing process and assembly 3 Environment and Life Safety 3.1 Environmental impact 3.2 Flammability rating 4 References 4.1 Notes 4.2 Student contributions 5 See also 5.1 Similar materials 6 External links 6.1 Additional resources 6.2 Leading manufacturers

Material analysis

MasterFormat Number: 09 25 00

Clay Earth Plaster is a practical, environmentally friendly alternative to cement, gypsum, acrylic, and lime plasters. It is compatible with the “breatheable” construction recommended for both historic and new buildings.

Traditional uses

Historically, plaster has always been a mud-like material made of many different earthen materials. Earth plasters are part of a timeless tradition.

There are examples of 1000-year old clay and mud plasters in China, Japan, India, Europe, the Middle East and Africa. Properly done, Clay Earth plasters are beautiful, easy to maintain and can outlast modern wall finishes.

Emerging uses / trends

We typically associate mud and clay plasters with certain architectural styles but they can be used successfully in any style of home including classic Cape Cods, and modern glass filled skyscrapers.

Today the most common forms of plaster are gypsum and cement. Both create hard brittle surfaces. They are very difficult to repair and over time, they crack because of this hard inflexible coat.

Clay plaster has a far longer working time than other plasters (up to several days if you need it) so you can work with confidence that the surface won’t “set” before you’ve achieved the desired finish. You can also reuse any excess plaster, even after you’ve mixed it and it’s dried, so there is no waste associated with the product.

Finish and aesthetic qualities

Clay Plaster comes in a large variety of colors and finishes.

American Clay Plaster (brand) offers the following finishes:

• LOMA
  • Loma provides a surprising range of textures for interior walls.
  • While always serving as a basecoat for all three of our Premier Plasters, LOMA™ as a final finish brings a finely honed polish to any wall surface.
  • Loma is the easiest of our three Premier Plasters to apply either with a trowel or spray on application.
  • Loma is the easiest plaster for do-it-yourself enthusiasts who have little or no plastering experience.
• PORCELINA
  • American Clay's smoothest plaster creates traditional opulent Old World marble smooth surfaces and lends a silky polished sheen to a wall surface.
  • Porcelina is the answer for elegant Italianesque or Contemporary walls.
  • Used over a base coat of LOMA
• MARITTIMO
  • The strongest of the three plasters because of the use of crushed shell aggregate.
  • The shell provides a speckled appearance that adds depth and subtle sheen to an interior environment.
  • Marittimo goes over a base coat of LOMA, and is as easy to apply as Loma.

Possible textures include:

• Float
• Mica
• Straw
• Blend
• Skip Trowel
• Sponge
• Steel Troweled
• Hand Textured
• Hand Painted

For color options visit: www.americanclay.com

Cost analysis

• Approximately $0.80 to $1.35 per square foot (not including shipping)

Material properties

Primary structural use

• Clay Plaster is used as a interior wall and ceiling finish.

Material performance

Negative Charge

• Natural clay maintains an incredibly dense molecular structure and shape, giving it the capacity to produce a self-generated negative charge upon hydration.
• Negative ions are proven to produce positive biochemical reactions in humans. A negative charge in a space acts on our capacity to absorb and utilize oxygen, causing us to have more energy and feel invigorated. Negative ions also have been proven to increase levels of the mood chemical serotonin, helping to alleviate depression, relieve stress, and boost our feelings of well being.
• Surrounding your interior environment with unsealed clay plasters, or clay paints, that produce Negative Ions will not only help neutralize the electromagnetic effect created by computers, appliances and synthetic plastics, but also will help eliminate static charge on walls.
• Your walls stay clean and will not attract dust! Also, by having clay plaster on a wall, you are helping to filter air of pollen and dander.

Life Expectancy

• If applied correctly, it should last the life of the wall.

Maintenance

• Easy to repair holes, dents or scratches with left over plaster.
• Typically no cleaning necessary. Clay repels oil from hand and dust accumulation because it is a naturally negative.

Reusable

• Plaster can be reused after mixed and set, simply rehydtrate mixture and apply.

Area Performance

• LOMA
  • Available in 50 lb. bucket or bags.
  • Coverage: 80 to 120 square feet in two coats per 50 lb. bucket or bag, depending on the substrate
• PORCELINA
  • Available in 50 lb. bucket or bags.
  • Coverage: 300-350 square feet per 50 lb. bucket or bag in one coat over a base coat of LOMA.
• MARITTIMO
  • Available in 50 lb. bucket or bags
  • Coverage: 160 square feet per 50 lb. bucket or bag in one coat over a base coat of LOMA.

Acoustic property

The acoustic properties are dependent on how many layers of plaster are applied.

Typically only 1/16" thick when applied to ceilings or walls, the R Value is < 0.3.

Manufacturing process and assembly

American Clay Plaster (brand) is manufactured in and uses materials from the US. Their products are made using a variety of natural clays, recycled and reclaimed aggregates, natural mineral pigments and a non-toxic mold inhibitor. As mentioned earlier, crushed sea shells are used in the MARITTIMO finish.

• Clay plaster can be troweled on like traditional plasters or sprayed on with a drywall hopper.
• Application can vary greatly based on desired finish

Environment and Life Safety

Environmental impact

Environmental alternative to cement, gypsum, or acrylic plasters

• Smallest carbon footprint per pound of any manufactured interior finish material

Recycled Content

• Marble quarries supply post-processing crushed stone from slab marble extraction
• Plaster bags are 100% recyclable back into manufacturing
• Pigment packaging 100% recyclable (type 1 plastics)
• Virtually no on-site waste (plaster can be rehydrated and reused)

Indoor Air Quality

• Plaster and pigments are 100% natural
• No added chemicals or off-gassing to affect indoor air quality
• Plaster limits moisture build-up helping maintain mold-free environment
• Molecular structure also produces a charge that reduces dust attraction to walls

Flammability rating

Fire rating: NFPA class A fire rated.

NFPA Class A fire rating: highly flame resistant; with the best rating at 0 and the worst at 250.

• American Clay Brand Plaster is a 5. Smoke spread = 0; smoke produced = 0.

Universal Building Code class 1 Non Flammable Wall Covering

• There is no “time rating” on the product because at a finished thickness of 1/16th of an inch, it will not add significant time delay in the burn-through of a fire.

References

Notes

Student contributions

• Amy Pagano, Spring 09

See also

Similar materials

• Plaster
• Eco-friendly paint
• Paint

External links

Additional resources

Leading manufacturers

• American Clay Plaster - [1]