TECHNICAL INFORMATION ON BUILDING MATERIALS

TIBI -36

FOE USE IN 'THE DESIGN OF LOU-COST HOUSING

THE NATIONAL BUREAU OF STANDARDS

UNITED JME3 DEPARTMENT OF COMMERCE

WASHINGTON, D. C„

September 28 ,_1_9_3 6_

PREPARATION OF PAINTS FRON SSUIPiiSTE PAINTS,

THINNING RSADY-KI XED PAINTS, AND

PREPARATION OF WATER 'PAINTS _

This is primarily a digest of the sections of Bureau of Standards

Circular No. 63 (November 17, 1917], "Paint and Varnish 7 ’;! and Technologic Paper No. 274 (December 15, 1924), "Use of United States

Government Specification Paints and Paint Materials", 2 by P. H. Walker

and E. F. Hickson, dealing with preparation of paints from semipaste

paints, the thinning of ready-mixed paints, and water paints and their

preparation.

The following papers contain additional information relative to

paint pigments, oil paints, and water paints:

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30 "Paint Pigments —White"

31 "Paint Pigments—Black, Red, and Lakes"

32 "Paint Pigments —Yellow, Brown, Blue, Green, and

3ronze"

33 "Federal Specification Paint Pigments and Mixing

Formulas 71 34 "Federal Specification Ready-Mixed Paints, Semipaste Paints and Mixing Formulas"

35 "Preparation of Paints from Paste and Dry Pigments"

43 "Aluminum Paints"

"'"Out of print. May be consulted in Government depository

libraries

.

pAvailable from Superintendent of Documents, Government

Printing Office, Washington, D. C. (Price 10 cents).

101036-C 1

Paint is "a mixture of pigment with vehicle, intended to he spread

in thin coats on surfaces for decoration or protection, or both,”l

The principal distinction between paint and varnish is that paint

contains an appreciable amount of pigment in suspension substantially

insoluble in the vehicle; while varnish consists of a liquid in which

resins or waxes contained therein are mostly in solution.

Semipaste paints may be poured from the container and are,

therefore, easier to break up than paste pigments which are quite

stiff. When more than one coat is required and the work is to be

done under skilled supervision, it is generally advisable to purchase semipaste paint,

heady-mixed paints as compounded are intended to be used for

final coats, or for one coat repainting work if the previously painted surface is in good condition. High grade ready-mixed paints reduced by a reliable paint manufacturer, if intelligently selected,

may be expected to give entire satisfaction. High grade service should

not be expected from low value products.

"hen skilled supervision is not available, it is frequently

best to use ready-mixed paint, since the manufacturers’ label provides

simple directions for reducing such paints for priming and body coats.

Preparation o f Paints from Semi pa ste Paint s

Although semipaste paints as compounded are sufficiently thin

to pour from the container, they require further breaking up and

thinning before they are ready to be applied. In preparing paints

from semipastc paints, the semipaste must be thoroughly mixed before adding the thinning liquids which should be done gradually

and with constant stirring until the paint is of proper consistency

for use. Such paints should be carefully strained before being applied,

Thinning Heady-Mixed Paints for Vari ous Uses

Hanufacturer *s Directions: For priming (first coat work on unpainted

surfaces), and body coat (second coat work) the ready-mixed paint

should be thinned according to directions usually provided by the

manufacturer. In following these directions it is generally advisable to pour off most of the clear liquid at the top of the container.

^3uoted from ’’Standard Definitions of Terms Relating to Paint

Specifications”, American Society for Testing Materials (1933),

pp. 735-739.

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The settled, pi.3r.1ent and the remaining vehicle should then be thoroughly

mixed by stirring with a stout paddle, A little of the remaining

liquid should he added and stirred thoroughly, repeating the process

until all is added. Should additional liquid he required, it may he

added in the same way. Paints should always he mixed and strained before using.

Speci f i c Dire ct ions : The following directions are provided to supplement those supplied by the manufacturer:

Priming soft p orous wo od; Add about one-half gallon raw linseed oil and about one pint of turpentine to each gallon of paint.

Priming hard or r esinous wo od : Add about one pint raw linseed

oil and about one-fourth gallon turpentine to each gallon of paint.

However, in recent years, there appears to he a trend toward adding

less oil to the finished paint for priming coats. Special priming

coat paints for wood have also appeared on the market. These

primers are formulated differently from the finish coat paint.

Body coats: Add about one pint turpentine or mineral spirits

to one gallon of paint,

Finish .coats: Use the paint as it comes from the can.

Caution : Driers should not he added to ready-mixed paints.

Wat, er Pa int s and fheir_ Preparation - whitewash

Lime, the basis of whitewash, provides a very sanitary coating

which is usually preferred for cellars and the interiors of outbuildings. It is the least expensive of all paints and, for certain

purposes, is the best.

Use of an insufficient amount of water produces "scorched"

lime which is generally lumpy and transparent. Too much water re*- tards the slaking process hy lowering the temperature.

Numerous substances, such as flour, skimmed milk, glue,

molasses, soap, alum, and sodium silicate are sometimes added to

whitewash to increase its adhesion.

When organic substances, such as flour, milk, glue, molasses,

etc., are added to whitewash, it is advisable to add some preservative to prevent putrefaction. The most commonly used preservatives

for this purpose are sodium chloride (common salt), zinc sulphate,

alum, and formaldehyde.

Caution : Whitewash containing organic matter should not be used in

damp interiors, even though preservatives are added.
Preparation o f Ordinary Hiitewash: Ordinary whitewash is made by

slaking about ten pounds of quicklime with two gallons of water. The

lime should be placed in a pail and the water poured over it. The

pail should then be covered with an old piece of carpet or cloth and

the whitewash allowed to stand for at least an hour. Before using,

sufficient water should be added to the mixture to bring bo brushing

consistency.

Bureau of Lighthouses Formulas: The following old formulas for whitewash issued by the Bureau of Lighthouses U. S. Department of Commerce

is claimed to be satisfactory for outside exposures, although better

formulas may be found in Bulletin 304-C described later herein.

’’Slake half a bushel of unslaked lime with boiling

water, keeping it covered during the process. Strain

it and add a peck of salt dissolved in warm water, three

pounds of ground rice put in boiling water and boiled to

a thin paste, one-half pound of powdered Spanish whiting,

and a pound of clear glue dissolved in warm water. liix

these well together and let the mixture stand for several

days. Keep the wash thus prepared in a kettle or portable

furnace, and when used, put it on as hot as possible with

pa inter ’ s or whitewash brush es .

A simple formula now given in Lighthouse Service instructions

is "to ten parts of best freshly slaked lime, add one part of best

Portland cement, mix well with salt water and apply quite thin.”

Ilis cellaneous I nforma tion and Formulas: For more practical information about whitewash and its application the Bureau of Lighthouses

suggests National Lime Association Bulletin 304-C ''Whitewash and

Cold-Water Paints, ”1 'The Paint Laboratory, National Bureau of Standards, is of the opinion that this information is the best on the subject that lias come to its attention.

Cement Dash

For certain purposes, especially on exposed places, a wash made

of hydraulic cement is preferable to whitewash.

Prepar ation; Cement wash is made by mixing three parts of Portland

cement and one part of fine sand, with any desired coloring' (e.g.

Venetian red), and adding sufficient water to produce as thick a mixture

as can be readily applied with a whitewash brush.

Available from the National Lime Association, 927 - 15th St.,

., Washington, D. C. (Free).

- 4 -

F. W,
Proprietary Brands : Excellent proprietary "brands of cement water

paints, in dry powder form, are available in white and about twelve

tints. The powder is generally mixed with water in equal parts by

weight, one pound powder to one pint water. These powders in

general are mixtures of white Portland cement, with or without

hydrated lime; and contain small amounts of moisture retaining

materials, such as calcium chloride; waterproofing agents, such as calcium stearate; small amounts of titanium pigment; and lineproof tinting colors, properly ground and blended by the manufacturer.

Calcimine

Cold-water paints or calcimines have as their basis whiting or carbonate of lime instead of caustic lime, as in whitewash. This

material itself does not adhere, and it is necessary to use a binder

of some kind, generally glue or casein.

Preparation of Ordinary Vfiii te Calcimine s; Ordinary white calcimine

may be made by mixing sixteen pounds dry whiting with one gallon water

until free from lumps, and adding a solution of one-half pound glue in one pint water. The glue may be dissolved by soaking for several

hours in cold water, and heating on a water bath (glue pot) until

completely dissolved. The addition of sodium phosphate to calcimine

has also been recommended.

Tint ing Hh i

t

e Calcimines : The tinting of white calcimines should be

done with colors that are not affected by lime, namely, yellow ocher,

siennas, umbers, Venetian red, para-red, maroon oxide, ultramarine

blue, ultramarine green chromium oxide, bone black, etc. If lampblack is used for tinting, it should be stirred in hot water containa little soap, or in cold water containing a small amount of borax.

Propr ietary Brands : Excellent proprietary brands of calcimines,

cold-water calcimines and hct-water calcimines, are available in white

and about twenty beautiful, soft tints. They dry rapidly and do not

give off objectionable odors. These coating materials are properly

ground and blended by the manufacturer who usually provides complete

mixing directions on the package. In the absence of such directions,

cold-water calcimines are generally mixed in the ratio of five pounds

of powder to three and one-half pints of water, and hot-water calcimines

in the ratio of five pounds of powder to five pints of water. All

calcimines should be strained before using’.

Typical Ca se in Calcimine Formulas: Casein is marketed in two forms,

soluble and insoluble. Since the insoluble form, pure casein, is the

one usually employed in calcimines, it is necessary to add some alkaline substance, such as soda ash (sodium carbonate), borax, or ammonia

to render it soluble. It is also necessary to add some preservative

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as carbolic acid (phenol), chromealum, thymol, or formaldehyde when

casein is used in calcimines.

Interior Us e: To prepare casein calcimines for interior use,

thoroughly mix in the dry state eight pounds pure casein, one pound

soda ash (58 percent), sixty pounds "gilders' bolted whiting”, and

twelve pounds plaster of Paris. The mixture should then be treated

with water to produce the desired brushing consistency and let stand

for a short time to allow casein to dissolve.

Exterior Use : Casein calcimines for exterior use may be prepared by dry mixing eight pounds pure casein, ten pounds air-slaked

lime, and one pound pulverized borax with sixty pounds of "gilders'

bolted whiting". This dry mixture should be kept in sealed packages

until needed, at which time it shoiild be mixed with water as for

interior use.

V/ater-resistant Calcimine : This type may be made by heating

one pound casein with one pint cold water, diluting with three quarts

ccld water, and adding eight fluid ounces ammonia. Stir this solution

until a smooth jelly is produced, after which, one-fourth fluid ounce formaldehyde (40 percent) should be added. This mixture acts as a binder into which whiting or any other pigment, white of colored,

not affected by alkali, may be stirred until a moderately thick paste

is obtained. The paste is then diluted with water, alcohol, turpentine, or linseed oil, as desired, until of proper brushing consistency.

Federal Specification : See TT-P-23 "Paint; Cold-Water, Casein-Binder,

Light Tints and White”, 1 covering two grades (whiting grade, dry

powder; and zinc sulphide, titanium oxide grade), and two types (dry

powder, and paste). This modern decorative material is available in

black, as well as white and a variety of soft, delicate tints. Its

popularity has increased enormously during the past two years, and

excellent proprietary brands of casein paints both in powder and

paste forms are now available and recommended instead of those mixed

by hand.

Casein cold-water paints are not as durable as oil paints,

especially for exterior application. Although sometimes used for

temporary exterior work, they are applied chiefly for decorating

plaster and other dry interior masonry surfaces. Before using coldwater paint, all iron and steel, such as nail heads, etc., should be

coated with oil paint to prevent rust stains. Come cold-water paints

when applied on masonry subject to dampness, such as cellar walls,

"^Available from Superintendent of Documents

ing Office, Washington, D. C. (Price 5 cents).

Government Print

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may turn black through the formation of mildew. Such paints should

always be used the same day as mixed. On most unpainted surfaces,

and particularly on wood, it is advisable to use a priming coat

prior to applying the cold-water paint. Generally speaking, coldwater paints should not be scrubbed with strong soap and water,

h/hen cleaning is necessary the paint may be washed rather gently

with mild white floating soap and water.