How to Make Lime Plaster

Lime plaster has been used to coat walls and floors for at least 11,000 years. Neolithic plaster masons began by burning limestone (calcium carbonate -- fossilized sea shells) to a dust called "quicklime." When quicklime (calcium oxide) is mixed with a little water it becomes fine crystals of slaked lime or calcium hydroxide. Lime plaster, lime mortar and old-fashioned whitewash are all preparations of calcium hydroxide. When any of these are exposed to the atmosphere, they chemically transform back into a coating of calcium carbonate or limestone which, archaeological evidence indicates, lasts for at least 11,000 years.

Six cups of water
Large bucket
Dust filter face mask
5 lbs. of hydrated lime
12.5 lbs. of coarse sand
Paint mixer attachment
Electric drill
8 oz. of animal hair
Trowel

Instructions

- 1
  Pour 6 cups of water into a large bucket. Put on a dust filter face mask.
- 2
  Pour 5 lbs. of hydrated lime into the bucket. Many gardening supply stores sell hydrated lime in bags as small as 5 lbs. and sacks as large as 100 lbs..
- 3
  Pour 12.5 lbs. of coarse sand into the bucket. Chuck a paint mixer attachment into an electric drill.
- 4
  Mix the plaster with the paint mixer attachment for about three minutes before you start to sprinkle animal hair into the mix. Animal hair is a traditional ingredient in lime plaster although some plaster masons report success with other fibers, including cellulose, when plastering straw bale homes.
- 5
  Continue to mix the plaster and add animal hair until the plaster mix incorporates 8 oz. of hair.
- 6
  Apply the plaster using common plastering methods holding a trowel at a 75 degree angle. Lime plaster sets more slowly than gypsum plaster.

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Interior Home Repair