TECHNICAL INFORMATION OH BUILDING MATERIALS

TIBM-31

FOR USE IN THE DESIGN OF LOW-COST HOUSING

THE NATIONAL BUREAU OF STANDARDS

UNITED STATES DEPARTMENT OF COMMERCE

WASHINGTON, D. C.

August 22, 19S 6

PAINT PIGMENTS—BLACK , RED, AND LANES

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

Circular No. 69, "Paint and Varnish", (November 17, 1 917)>^ and Technologic Paper No. 2jh, "Use of TTnited States Government Specification

Paints and Paint Materials", (December 15, 192U),^ "by P. H. Walker and

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

uses of black and red pigments, and lakes.

The following -oarers contain additional information relative to

paint pigments, oil paints, and water paints:

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30 "Paint Pigments—White"

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

Bronze"

33 "Federal Specification Paint Pigments and Mixing

Formulas"

3k "Federal Specification Ready-Mixed Paints, Semipaste Paints and Mixing Formulas"

35 "Preparation of Paints from Paste and Dry Figments"

36 "Preparation of Paints from Semipaste Paints, Thinning

Ready-Mixed Paints, and Prenaration of Water Paints"

U3 "Aluminum Paints"

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

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

^Out of print. May be consulted in Government deuository libraries.

p^Available from Superintendent of Documents, Government Printing

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

-Quoted from "Standard Definitions of Terms Relating to Paint Specifications", American Society for Testing Materials (1933), pp. 7^5-7"*9.

0G1736~C 1
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assumed that ragmen ts composed of very fine particles, having high

refractive indices, provide the greatest covering p owe r and opacity.

Lake ; In paints a lake is "a snecial type of pigment consisting

essentially of an organic soluble coloring matter combined more or less definitely with an inorganic base or carrier* It is characterized

generally by a bright color- and a more or less nr on ounce d translucency

when made into an oil paint

,

Federal Srecifica'ti ons are specifications adonted by the Federal

Specifications Fxecutive Committee and annroved by the Director of

Procurement, Treasury Department, for use of all deoartments and

establishments of the Federal Government.

Black Pigments-—Lampblack

Production and General Composition; Lampblack is soot produced by the

incomplete combustion of oils, fats, resins, or resinous woods. It is more or less pure carbon.

Charac ter i st: c

s

: It is grayish black in color, very bulky, remarkably

permanent, and has great color strength.

Fse : Lampblack is largely used to produce a fine blue gray, by mixing

it with white. It is also used as a solid color, although it is not so bright a black as some other pigments.

Federal Specification : See TT-L-71? 'JLaunpDlack; Dry, Paste- In-Japan:,

Paste-In-Oil. n

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Gas Black or Carbon Black

Production : Gas black is closely related to lampblack, and is produced

in a similar manner though from natural gas.

Characteristics : It is far blacker looking than lampblack, With white,

gas black gives a brownish or smoky tone to the gray which is pot

desirable. Both lampblack and gas black, when burnt, should not leave

more than a small fraction of 1 percent residue.

^Quoted from "Standard Definitions of Terms Relating to Paint

Specifications", American Society for Testing Materials (1933)*

PP. 735-739.

p . 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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Varieties : Thermatomic black and acetylene black are varieties of gas

black of recent introduction.

Use : Gas black is used as a solid or body color and in -printing inks.

Bone Black

• Production and General Composition : Bone black is uroduced by heating

bones in a retort from which the air is excluded. The resulting bone

charcoal, which is ground fine, contains 10 to 20 -percent carbon. The

remainder is largely calcium phosphate. "Ivory black" or "Drop black"

made from 'ivory chips and cuttings is a high grade bone black.

Characteristics : It is fine black in color. Its color strength may be

not more than l/g as great as lampblack, and the gray it gives with

white is not so nure. All kinds of bone black may contain Prussian

blue, which is added to modify the color. A much stronger color may

be made from bone black by removing the mineral matter with hydrochloric

acid.

Use : Bone black is used as a body color.

Federal Specifications : See . TT-B-601 , "Bone-Black; Dry, Paste-In-Japan,

Paste-In-Oil „

Charcoal Black

Producti on : Charcoal black is of vegetable origin and uroduced in the

- same manner as bone black. Sources —peach and plum pits, cocoanut shell,

cork waste, and grapevine cuttings.

Use ; The blue black or vine black grade made from grapevine cuttings is

used by artists in water colors.

Graphite (Black Lead or Plumbage)

General Composition ; Graphite is a form of carbon found as a natural

mineral. That used in paint sometimes contains as much as 85 percent

graphite, the remainder siliceous material. Sometimes silica or other

pigments are added* thus reducing the graphite content of the pigment

in a graphite paint to no more than Ho percent.

Characteristics ; Graphite is extremely permanent. Its dull grayish

black color renders it undesirable for any use except on inconspicuous

surfaces. Ac he s on gr aphi t e is an artificial graphite of extremely fine

texture, sometimes used in paints. This graphite may contain as little

as 0.1 to 0.2 percent ash.

Graphite Faints : "Brown graphite", "green graphite", and ,r red graphite"

paints are graphite paints with some other added coloring matter.

Use ; Graphite is used largely in paints for iron roofs and other iron

surfaces.

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Black Oxide of Iron

Characteristics : This is an artificial- pigment having the approximate

composition of- magnetic iron oxide.' It is a soft, black, oowder.

Use : It is used in • anti-corrosive paints and in black cold water oaints.

Miscellaneous Black Pigments

Types : Black mineral substances, such as coal, shale, etc., are ground

and sold under a variety of names, such as "mineral black", "keystone

filler", or "iron filler." Their use is generally confined to paints

applied as fillers for rough surfaces.

Red Pigments—Indian Red

Production and G-e neral Compo s ition : Indian red is produced artificially

by roasti' 1 ferrous sulohate (green vitriol), which yields colcothar or rouge, of dors from bright scarlet to ourolish red. It should contain

at least ^5 percent ferric oxide, •

Characteristics : This oigment is of a dark purplish color, very permanent,

and is not affected by light or by other pigments with which it is mixed.

As a body color it is very onaaue and may be extended by the addition of

large proportions of inert material, and yet cover very well. "Turkey

red" is the name given to iron oxid.es of bright red color.

Use : Indian red is used largely to afford pure tints with white.

Tuscan Red

Produc tion : Best grades of Tuscan red are produced by enriching Indian

red with an Alizarin lake dye. Cheaper dyes of inferior quality, and

bases other than Indian red are sometimes used. However, the resulting

colors soon fade and such products are worthless for special uses for

which Tuscan red is adapted*,

Characteristics : Tuscan red possesses a beautifully subdued crimson tone

of great color strength, which is usually reduced by mixing it with

barytes, whiting, or gypsum. It is very permanent and will stand temperatures as high as 300 ° to 350°^ without changing.

Use : Tuscan reds -are. extensively ->used to withstand vigorous exposures.

They are used for painting steam pines, radiators, imnlements, machinery,

end passenger cars, > ?

Venetian Red

Production and General Composition : Better grades of Venetian red are produced by mixing calcined ferrous sulphate with gypsum. The calcined

ferrous sulnhate is mixed with barytes or whiting in the manufacture of

inferior grades.

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Charac teristics i Good Venetian red is always brick red in color. It has

excellent body and, if free from whi'ting, great permanency. It may be

mixed safely with any other pigment. Cheap commercial calcined earth

' reds, which are not much more than clay possessing sufficient iron to

color, and sold as Venetian reds should not be confused with high grade

Venetian reds, as their use, except in cases where reduced cost is the

sole object, is likely to lead to disappointment

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Use ; Good Venetian red can be used for almost any kind of painting in

oil or for "distemper" (water paint). It is very widely used when an inexpensive and reliable pigment is needed. However, as an exterior

paint on metal, an iron oxide pigment with a siliceous base is generally

pre ferred.

Red Lead

Production and General Composition : Red lead is produced by heating

metallic lead forming lead monoxide (litharge) which is converted into

red lead by additional heating. Fure red lead (Pb^O^) may be regarded

as 1 part lead peroxide (PbC^) and 2 parts lead monoxide (PbO),

Painters 1 red lead contains 85 to 99 percent Pb-^0^, the remainder of

the unadulterated samples being lead monoxide unchanged in the manufacturing process. By a special fume process, red lead of exceeding fineness

can be made, ' Red lead can be bought toda?/ which is guaranteed to contain at least 9S percent true red lead (Pb^0i|).

Characteristics : Red lead is a brilliant scarlet red pigment. It is

blackened by hydrogen sulphide or other sulphur compounds, and has a tendency to whiten upon exposure to atmospheric agencies. As its chief

use is for first or priming coats, these defects are of no consequence.

Ordinary red lead, 'containing less than 95 percent Pb^O^, of itself,

is a good drier. When mixed with oil it will solidify to a hard mass within a short time, therefore, it should be used immediately after, or

at most, within 2U hours of mixing. The practice of grinding red lead

to a paste form in a non-drying oil is not recommended. When ground

mixed with other pigments, such as silica, it should not be sold as pure red lead.

There is a high grade red lead on the market containing about 98

percent Pb-^O^ which, when ground in linseed oil to a paste form, does

not harden in the container, and appears to be equal in every wav to

freshly mixed dry lead.

Red lead paint is very heavy, flows on stiffly, has a tendency to

sag, and is not likely to cover as much surface as white lead. If

properly prepared and applied it forms a very tough, adherent coating.

Orange Mineral is a form of red lead having a lower specific

gravity and lighter color.

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Use ; Red lead is used for its protective action, and not as a color or for tinting purposes. Although it is probably the best, and most widely

used pigment for priming coats on all kinds of surfaces, red lead is not

commonly, used for priming ^ood because of its color, which requires more

coats to hide when white or light tints are desired than would be needed

if light-colored pigments were used. For the protection of iron and

steel from outdoor exposures, red lead linseed oil paints are probably

the best. This paint should weigh not less than 25 pounds per gallon.

Federal Specifications : See TT-R-191 , "Red-Lead; Dry and. Paste-In-Oil .

Avoid storing red lead paste in places of high temperature. Red lead

should not be purchased in paste form unless it is to be used within

three months after shipment by the contractor.

English Ve rmi lion

General Composition ; English vermilion is mercury sulphide.

Character ^ ':ics: It is very opaaue , a beautiful scarlet, but not a very permanent color.

Use: English Vermilion is used principally for striping, but because

of its high price, its place for other purposes has been taken by modem

organic lakes,

American T hrmilion (Scarlet Lead Chromate, Chrome Red)

General Composition : American vermilion is a basic chromate of lead.

Characteristics : It is a brilliant scarlet, coarsely crystalline powder,

possessing good hiding power and color strength. It is fairly permanent

to light, but is blackened by sulphides. Grinding turns it to a dull

yellow.

Use : As a protective pigment in paints for iron and steel, American

vermilion equals or excels red lead. However, cost prohibits its wide

nse . It is sometimes used as a color pigment, but for this purpose its

place is largely, taken by coal-tar reds.

Cadmium Red or Selenium Red

General Composition : Cadmium red or Selenium red is a red inorganic

.pigment of recent introduction. It is a manufactured pigment consisting

of cadmium sulphide and cadmium selenide.

Charac teristics : This is a brilliant red pigment of considerable opacity,

and very stable to light.

Use : It is used in enamels.

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«' Lakes “V ; "

Production : Lakes are formed by combining the coloring matter of certain

dyes with metallic bases. Most of the natural lakes are obsolete, the

great bulk being prepared from synthetic (coal-tar) dyes.

Characteristics ; In general they range in color through every shade of

red, purnle, and maroon. Lakes are brilliant, transparent, possess

high- color strength, but are frequently very fugitive to light.

Types:

Alizarin Lakes are produced artificially from coal-tar. They are very eermanent, and possess fair hiding power especially if precipitated

on an excess of opaque base.

Carmine Lakes are formed by combing carmine, the coloring matter of

cochineal, with alumina. They are deep, fiery-scarlet powders, fugitive

to light.

Rose fi nk and Hose lakes are made from brazilwood or artificial

coal-tar dyes.

Artificial Vermilions: When urouerly made, artificial vermilions

are very brilliant ,

. and possess high color strength. They are more permanent than genuine English Vermilion, but do not have the same hiding

power. .Some are slightly soluble' in oil, and have a tendency to bleed"

into other colors, especially white. Artificial vermilions in some cases are also injuriously acted upon by ammonia vapors and'-many pigments.

Permanent and satisfactory artificial vermilions are made from

Alizarin as a lake, extended by red lead, blanc fixe, or whiting.

Red Organic Pigment Dyes : The introduction of synthetic dyes preparedfrom coal-tar, gave rise to the three following very important red organic

pigment dyes, Toluidine toner is the best bright red pigment at the paint 1 manufacturer's disuosal (See Federal Specification TT-E-531&)®

Parani traniline red is an excellent red. pigment dye, Lithol red is another

good, red pigment dye.

Tungstate-Molybdate Lakes' : Such lakes have appeared quite recently

in red, green, yellow, and blue. They are being used in the printing

ink industry, and to some extent by paint manufacturers to keep green

and blue tints from changing color' in the container, -I

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