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Historic Preservation - Technical Procedures

Spectitle:

Properties And Uses Of Whitewash Paint

Procedure code:

0990005S

Source:

Interior's Handbook For Historic Interiors - Vol. Ii

Division:

Finishes

Section:

Painting

Last Modified:

02/24/2012

Details:

Properties And Uses Of Whitewash Paint



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 binders
    include 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.

                             END OF SECTION