Properties and Uses of Whitewash Paint

This standard includes guidance on the preparation of whitewash paint. It also includes general information on its composition, characteristics, advantages and uses.

Composition

• A water-based paint.

• Composed primarily of water and lime mixed to form a thin paste.

• Binders are often added to improve the durability and chalking resistance of the lime-water mixture. Some of these bindersinclude salt, sugar, flour (rice, wheat, rye or buckwheat), starch varnish, glue, skim milk, whiting, brown sugar, vegetable oil plasticizer, casein, formaldehyde, borax or sulphate of zinc.

• Alum was sometimes added as a hardener to prevent the coating from rubbing off.

• Carbolic acid was sometimes added to create “sanitary” whitewash.

• Indigo and bluing were popular additives in counteracting the tendency of some binders to yellow.

• Whitewash can be tinted; historically, they were tinted with earth pigments, brick or stone dust; currently, lime-fast pigments are recommended.

Characteristics

• Adheres best to rough porous surfaces. It does not adhere well to smooth porous surfaces.

• When applied to a surface, the mixture forms a thin opaque film of calcium carbonate (Plaster)

Advantages

• Fairly easy to make.

• Non-yellowing (because there is no oil binder).

• Less expensive than other finishes.

• Effective in adhering to masonry surfaces.

• Considered a “sanitary” coating exhibiting disinfectant qualities (i.e. Sometimes used to retard the decay of wood).

• Somewhat effective as a fire retardant and thermal insulator when applied in thick layers.

Uses

• Historically used on the exterior to reflect heat.

• Also historically used to protect fruit tree trunks from frost and insects.

Mixes

Whitewash Mix For General Woodwork

NOTE: This mix has good adhesion and chalk resistance. It can also stand covered for several days before using.

• Make the lime paste by soaking 50 lbs. of hydrated lime in 6 gallons clean water - OR - slaking 25 lbs. of quicklime in 10 gallons of boiling water. Either combination will make about 8 gallons of paste.

• Dissolve 15 lbs. of salt or 5 lbs. dry calcium chloride in 5 gallons of water.

• Combine with lime paste and mix thoroughly. Thin with fresh water as necessary.

Whitewash Mix For Masonry (Brick, Concrete Or Stone)

NOTE: Mix only enough for a few hours use.

• Combine 25 lbs. hydrated lime with 25 lbs. white Portland cement.

• Add 8 gallons clean water and mix thoroughly.

• Add a dollop of white casein glue such as Elmer’s brand glue to the mixture.

• While mixing, the wash will start out very thick, slowly developing the consistency of heavy cream. If desired, adding 1-2 lbs. of dry calcium chloride, mixed in a small amount of water before using, to reduce chalking.

Whitewash Mix For Plaster

• Make the lime paste by soaking 50 lbs. of hydrated lime in 6 gallons clean water - OR - slaking 25 lbs. of quicklime in 10 gallons of boiling water. Either combination will make about 8 gallons of paste.

• Soak 5 lbs. of casein in 2 gallons of water - approximately 2 hours or until thoroughly softened.

• Dissolve 3 lbs. of trisodium phosphate in 1 gallon of water; add to the lime solution, and allow the mixture to dissolve.

• Allow both the lime paste and the casein to thoroughly cool.

• Stir the casein solution into the lime paste. Just before using, dissolve 3 pints of formaldehyde in gallons of water; SLOWLY add this solution to the whitewash; stir frequently; thin the mixture as desired.

-OR-

• Make the lime paste by soaking 50 lbs. of hydrated lime in 6 gallons clean water

-OR-

• slaking 25 lbs. of quicklime in 10 gallons of boiling water. Either combination will make about 8 gallons of paste.

• Dissolve 6 lbs. of salt in 3 gallons of boiling water, and allow to cool.

• Add this solution to the lime paste.

• Stir in 3 lbs. of white Portland cement

General Notes

• Before whitewashing any surface, gently wash the surface with vinegar. Be sure that brushes and pails are clean; be sure to strain the wash.

• Always slake the lime with boiling water and cover container with sackcloth or burlap to keep in the steam.

• Never let the lime dry up - when the lime has broken up, keep covered.

• When the lime has thinned to the right consistency, add 2 tablespoons of salt to each pail of wash.

• Add pigments to achieve desired color.