TECHNICAL INFORMATION ON BUILDING MATERIALS

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FOR UfSE IN THE DESIGN OF LOW-COST HOUSING

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THE NATIONAL BUREAU OF STANDARDS

UNITED STATES DEPARTMENT OF COMMERCE

WASHINGTON, D. C.

August 29, 1936

PAINT PIGMENTS—YELLOW, . BROWN, BLUE, GREEN, AND BRONZE

This is urimarily^a digest of the sections of Bureau of Standards

Circular No, o9> "Paint and Varnish", (November 17, 1917),'*' and Technologic Paper No. 274, "Use of United States Government Suecification

Paints and Faint Materials", (December 15, 1924), ^ Ly p, H. Walker and

E. F. Hickson, dealing with general composition , characteristics, and

uses of yellow, brown, blue, green, and bronze pigments.

The following papers contain additional information relative to

paint pigments, oil paints, and water paints:

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"Paint Pigments—White"

"Paint Pigments—Black, Red, and Lakes"

"Federal Specification . Paint Pigments and Mixing

Formulas"

"Federal Specification Ready-Mixed Paints, Semipaste Paints and Mixing Formulas’"'

"Preparation of Paints from Paste and Dry Pigments"

"Preparation of Paints from Semipaste Paints, Thinning

Ready-Mixed Paints, and Preparation of Water Paints"

"Aluminum Paints"

Pigments are "the fine solid warticles used in the preparation of paint,

and substantially insoluble in the vehicle, "3 In general, it may be

^Out of print. May be consulted in Government depositor}*- libraries.

pAvailable from Superintendent of Documents, Government Printing

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

^Qpioted from "Standard Definitions of Terms Relating to Paint

'Specifications", American Society for Testing Materials ( 1 93 3 )

PP. 735-73 9 .

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assumed that pigments composed of very fine particles, having high re- fractive indices, provide the greatest covering power and opacity.

Federal Specifications are specifications adopted hy the Federal Specifications Executive Committee and approved hy the Director of Procurement, Treasury Department, for use of all departments and establishments

of the Federal Government.^

Yellow Pigments—Chrome Yellow

General Composition and Types ; Chrome yellows are compounds of lead

with chromic acid.

Chrome Yellow Medium is a nearly pure lead chromate.

I Chrome Yellow Light , Lemon, or Canary contain a considerable amount

of lead sulphate or other insoluble, lead salt, intimately mixed with

lead chromate,

Chr ome Yell 6w Q range is a basic chromate precipitated from alkaline

solutions, ranging in color from pale orange to almost scarlet.

Characteristics : Chrome yellows range in color from deep orange to light

yellow. They are colors of . considerable brilliance, good color strength

and hiding power, fairly durable but slowly affected by atmospheric

conditions. Sulphides turn them black. Hence, ultramarine blue containing sulphide must not be mixed with them. They cannot be used with

silicate of soda, lime, or other alkaline substances as such substances

turn them to an orange or red color.

Federal Specification : See TT-C-291 , "Chrome Yellow; Dry, Paste-In-Japan , | Paste- In-Oil (Lemon, Medium, Orange)."

Zinc Chromate and Barium Chromate

Characteristics : Doth zinc and barium chromate are light yellow in color,

quite permanent., but lower in color strength and hiding power than lead

chromate. The zinc chrome is not a pure chromate, but appears to be a

double salt.

Use: Their use in paints is limited because of cost, although at the

present time, the use of zinc chrome in rust inhibitive priming paints

for metal is growing.

Copies of all Federal Specifications mentioned in this digest may

be obtained from Superintendent of Documents, Government Printing Office,

Washington, D. C. (Price 5 cents each).

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Yellow Ocher

General Composition : Yellow ochers are natural earths containing hydrated

oxide of iron (linonite, SFegO^^l^O) as the coloring matter. Various

ochers contain 10 to 60 percent hydrated oxide, -the remainder being

siliceous matter or clay.

Characteristics and Grades : In color they vary from pale yellow (citron)

to very dark, almost olive. When of good quality, yellow ochers are ex- cellent uigments, are permanent in color, and work well with all vehicles

and other pigments. With white thev produce fine cream or "buff tints.

They are used primarily as a tinting color.

French ocher is the "best grade. English ocher is darker in color.

American ochers range from those that are fairly good, though lacking

in ouacity, "brightness, tinting -power, and freedom from grit, to those

that are simply mud. Golden ocher is ocher- strengthened in color and

given a

' r ellow tone through the addition of chrome yellow, which fades

after a time, leaving only the natural ocher effect.

Federal Sueoification : See TT-0-111, "Ocher; Fry, Paste-In-Japan , and

Paste-In-Oil

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Raw Sienna

General Composition : Raw siennas resemble yellow ocher in general

composition, being earthy substances colored by hydrated iron oxide.

There is usually a little manganese oxide present. Rest grades are known as "Italian siennas".

Characteristics : Raw siennas are brownish yellow in color, and more

transuarent than the yellow ochers. With white they produce beautiful

cream tints which have greater color strength than ochers.

Use: Raw siennas are invaluable as staining and graining colors. They

are -undesirable for body colors.

Yellow Oxide of Iron

Production : Yellow oxide of iron is produced on a large scale by

precipitating a solution of ferrous sulphate with lime or soda ash,

and then oxidizing the ferrous hvdroxide by aerating it with hot air.

Characteristics : It is uniform, very soft in texture, and possesses a tinting strength which is several times greater than that of yellow

ocher. It contains about 90 percent ferric hydroxide.

Use : Yellow oxide of iron, at the present time, is used extensively as a staining and tinting pigment. It is also used largely in enamels,,

particularly those of the synthetic rosin type.

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Cadmium Yellow

Character!-sties. and Use :- Cadmium yellow is a sulphide of cadmium, used

in enamels. It is also prepared as cadmium lithopones, which are cheaper

than the pure cadmium sulphide.

Han sa Yellow

Characteristics .and Use : Hansa yellow is an organic, yellow pigment dye.

It is the most permanent yellow pigment on exposure to sunlight. Although

very expensive, it is used_ to some extent in Yellow lacquers and synthetic enamels.

Brown Pigments—Burnt Sienna

Production and Color ; Burnt sienna is uroduced by calcining raw sienna

which changes its color to an orange red or subdued red "brown of great

richness.

Kinds : "House Painters Bu rnt Sienna11 is strong in coloring matter, opaque,

and is intended to serve as a tinting color. "Grainers 1 Burnt Sienna"

is chosen for its transparency, richness, clearness, and is used as a body color (characteristic cherry), especially in graining. It is also

used extensively for producing the conventional mahogany, in which case,

it is generally strengthened in reddish tone by adding rose pinlc or similar red colors. ''

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Paw Umber

General Composition : Paw umber is a natural earth pigment, similar in

composition to the siennas but containing considerable amounts of

manganese .oxide. Best grades, known as "Turkey umber", come from

Cyprus.

Characteristics and Use ; Raw umber has a yellowish brown color with an olive tone. It is permanent, mixes well with vehicles, is of medium

opacity, and fair strength. It gives drab tints with white, and a great variety of other tints when mixed with colored pigments, for

which purpose it is extensively used.

Burnt Umber

General Composition : Burnt umber is calcined raw umber.

Characteristics : It has a rich brown color, which, while darker than raw umber, should be free from redness.

Use: Burnt umber is used for the. -same purpose as raw umber. However,

the tints formed are of a different 'order of drab.

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Metallic Sr owns or Mineral Browns

Pro Inc t ion and Colors : Metallic ‘browns or mineral "browns are uroduced

from native ores which, iroon roasting, develou colors ranging from

"bright red "brown to dark -on role

Charac teri stic s : They are ouaoue , fairly -permanent, changing "but little

on exposure and can "be mixed with other uigments with good results.

Use : Such "browns are extensively used to uaint roofs, barns, iron

bridges, and similar surfaces where a good substantial covering is

reouired without much regard for beauty of finish.

Vandyke Brown (Cassel Earth or Cologne Earth)

C-eneral Composition : Vandyke brown is a uigment of carbonaceous

character usually found in or near bogs.

Characteristics and Use : This pigment is soluble in dilute alkali,

forming a solution which may be applied to wood and ureciuitated in

the grain with dilute acid giving a very good and uermanent walnut

stain. When ground in oil and thinned with turpentine, it makes a good walnut oil stain which is not too transuarent and is decidely

uermanent. However, it does retard very strongly the drying of

linseed oil.

" Sau brown11 is a commercial dry soluble form of Vandyke brown.

The color of Vandyke browi may also be obtained by using burnt

umber, drou black, and Prussian blue, producing a color that is permanent, but lacking the transparency of true Vandyke brown.

Synthetic Brown Oxide of Iron

Production and Characteristics : Synthetic brown oxides of iron are very rich shades of brown uigments made synthetically from iron salts.

They are uniform, soft in texture, very strong in tinting strength,

and generally contain over 95 uercent oxides, of iron.

Blue Pigments—Prussian Blue

General Composition : Prussian blue is an oxidized ureciuitate uroduced

by ureciui tating uotassium ferrocvanide with ferrous suluhate.

Characteristics and Use ; Prussian blue, which is a characteristic dark

blue in color, is a transuarent uigment of great strength, 1 u'ound

giving to a ton of white lead a decided sky blue tint. It is fairly

permanent exceut in contact with alkalies or lime, which decolorize

it rauidly. With white uigments it should give a decided blue tint,

not uurulish or muddy. As Prussian blue is very fine in texture, it

does not settle in the vehicle, and hence it is used as a dipuing

paint.

Pederal Suecificatiori ":

' See TT-P-691, "Prussian-Blue; Dry, Paste-In-Japan

Paste- In-Oil."

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Ultramarine Biue

Production : Ultramarine blue is produced artificially by heating' together clay, silica, sodium carbonate, sodium sulphate, charcoal, rosin

and sulphur. The resulting oroduct is then ground, roasted, and washed

Characteristics : In color this "pigment varies from a pure blue to

colors "bordering on green (green ultramarine). It is bright but of

low color strength. Although it is affected by weak acids, it is permanent when exposed to sunlight, alkali, or lime. The sulphur in

ultramarine darkens white lead carbonate ,. and discolors chrome yellow

and other colors containing lead.

Use : Ultramarine blue is used largely in house -painting for mailing

tints with zinc white.

Federal Speci ficat ion: See TT-U-^51. "Ultramarine-Blue; Dry, PasteIn-Japan, Paste-In-Oil .

Cobalt Blue

General Composition : Cobalt blue is a compound of oxides of aluminum

and cobalt . .

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Characterist ics : It has a fine greenish blue color, -permanent to light,

and is not affected by alkali, lime, or acid. It can be mixed with any

other pigment or color. Because of the high price of genuine cobalt

blue, the so-called commercial -product is a suitable ultramarine blue

mixed with a little zinc white to .-provide a close imitation of cobalt

blue

Blue Lead

General Composition : Blue lead is essentially a basic lead sulphate’

with an excess of lead oxide mixed with varying small quantities of

lead" sulphide , lead sulphite, zinc oxide, and carbon.

Characteristics : It is a dark blue-gray -pigment, affected by exposure

to light which fact is of little importance as blue lead is not used

for coloring power. After drying, when mixed as a paint, it is com- paratively immune against darkening by coal gas.

Use: Blue lead is used to a considerable extent as a protective coating

for metallic surfaces.

Federal Specification : See TT-B-Ug6, "Blue-Lead; Basic-Sulphate, Dry

and Paste-In-,Oil

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Monastral Blue

Characteristics and Use : Monastral blue is a new, blue pigment dye

(copper phthalocvanine) that has appeared on the market, which gives

a very beautiful, blue .tint. It appears- to be destined f-omuse as.' a’ g; pointing ink pigment. ’

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'' jJi ' ( Green' Pfgmdhts—Chrome Green -

Production : Chrome green can' be made simply "by mixing together Prussian

blue and Chrome yellow. However, in color works, the necessary solutions to produce both Prussian blue and chrome yellow are made up and

then mixed together, the resulting chrome green being_a very intimate

mixture of the blue and yellow.

Characteristics : In tone the mixtures range from very rale yellow

green to a ver:r deep blue green. They have great covering power and

good color strength, but are not very durable and are subject to the

limitations' of both Prussian blue and chrome jrellow.

Common Grades and Use : "Commercial Greens" are composed of about 75

percent barvtes or silicate to 25 -percent color. As a body pigment,

commercial greens answer very well. Pure Green known commercially as "chemically uure" is preferred for tinting purposes.

Federal Suecification : 3ee TT-C-236, "Chrome, Green; Pure, Pry, PasteIn-Japan, Paste-In-Oil .

Chrome Oxide Green

Grade

: True Chrome Oxide Green is chromic oxide (CrpO^), a rather

expensive, -permanent, dull color of satisfactory hiding- power. " C-uignets 1 Green" or "Viridian" is a carefully made product of the best grade, which

is more or less hydrated and usually contains boric acid. "Chrome Ocher"

is a clay stained with chromic oxide. It has little value.

Federal Suecifications : See TT-C-271, "Chrome ,’ Green ; Oxide."

Emerald Green

General Composition and Use : Emerald green is -poisonous copper acetoarsenite, known as "Paris Green", which is extensively used as an insecticide. Its use as a paint pigment has almost entirely ceased.

Verdigri

General Composition : Verdigris is a basic acetate of copper.

Characteristics : It possesses a pale bluish green color which is not

permanent.

Use : Verdigris is used to some extent for decorative effects, and in

marine paints as a protection against barnacles.

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. Green Earth - (Terre Verte , or Verona Green)

General Composition ; The so-called' green eartlis are usually complex

silicates of magriesium, or other ajlhali "base and ferrous iron.

Characteristic

; They are uermanent, semiopaque, and their colors

are dull "bluish green varying to a "bluish gray.

Use : Although their chief use is in " disterrroer" (water paint), they

are used somewhat by manufacturers of mixed paints to produce certain

neutral greenish tints with white. A good quality of> green earth

brightened with certain basic coal-tar dyes is used as a cheap limeproof green color.

Metallic Pigments ("Bronzes)

Bronze Paints : Very finely divided metals or alloys are used in the

so-called bronze uaints^

Aluminum Bronze is metallic aluminum.

Conner Bronze is metallic copper.

Gold Bronze is the term applied to finely divided alloys of : copper, zinc, and tin which have colors resembling gold.

Bronze Powders generally contain small amounts of oil or fatty matter

such as stearine. They may be dyed*with coal-tar dyes, resulting in

brilliant reds, greens, blues, nurnles, etc. The dyed colors are not permanent on exposure to Sunlight.

Federal Specification : See TT-A-U76, "Aluminum-Powder; (For) Paints

(Aluminum-Bronze-Powder) » "

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