TECHNICAL INFORMATION ON BUILDING MATERIALS

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FOR USE IN THE DESIGN OF LOU-COST HOUSING

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THE NATIONAL BUREAU OF STANDARDS

UNITED STATES DEPARTMENT OF COMMERCE

WASHINGTON, D. C.

May 5, 1937

VOLATILE PAINT AND VARNISH THINFERS1

This is chiefly a digest of sections of applicable Federal Soecifications^ and ef the following publications of the National Bureau of

Standards dealing with turpentine, substitutes for turpentine, composite

vehicles, and less important volatile thinners.

Circular No. C$9, "Paint and Varnish", (November 17, 1917)?^

Technologic Paper No. T274, "Use

fication Paints and Paint Materials",

Walker and E. F. Hickson.

cf United States Government

(December IN, 1924), by P.

SpeciH.

Turpentine

Production and Types : Turpentine, a valuable and widely used volatile

thinner for ail paints and most oil-resin varnishes, is produced (a) by

distillation of resin from the pine-tree yielding " gum sp irits of tur- pentine" , (b) by either steam distillation or destructive distillation

of the pins wood, yielding " wood turpentine", (c) in the form of sulrhate

wood turpentine , a by-product of the paper pulp industry.

Volatile thinners consist of that portion of paint, water excepted,

which is volatile in a current of steam at atmospheric pressure.

2 Specifications adopted by the Federal Specifications Executive

Committee and approved by the Director of Procurement, Treasury Department,

for use of all departments and establishments of the Government. Conics

of Federal Specifications mentioned in this digest may be obtained from the

Superintendent cf Documents, Washington, D. C. (price 5 cents)

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Out of print and not available by purchase, but may be consulted in

Government depository libraries.

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Available from the Superintendent cf Documents, Washington, D. C.

(Price 10 cents)
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Properties and. Use ; Turpentine has excellent "flatting" and good solvent

properties. It has excellent penetrating qualities, evaporates in a satisfactory manner, and is the "best solvent for oils, etc., occurring in

woods. Therefore, it should he used in priming coats on new wood. There

is no objection to using it in all subsequent coats. When paints containing 'varnish require additional volatile thinner, It is safest to use turpentine. • ,

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' Federal Specifications : • See LLL-T-791a s "Turpentine; (For) Paint, Type I",

covering what is known as gum spirits of turpentine, steam-distilled wood

turpentine, and sulphate wrod turpentine; and LLL-T-792 9 "Turpentine; (For)

Paint, Type II", covering what is known as destructively distilled wood

turpentine.

There is practically : no difference in evaporation of the two types.

However, there is evidence that wood turpentine in certain cases is a some- what better solvent than gum spirits. Differences in solvent power are immaterial-in thinning oil paints, but in the manufacture of certain varnishes

they are important. Turpentine has proved to be very helpful in improving

the brushing properties of some of the new synthetic resin varnishes and

enamels. In specifying wood turpentine, it is advisable to agree upon a standard sample for odor.

Turpentine Substitutes

Substitutes for turpentine are usually prepared from suitable fractions

of petroleums. They vary greatly in specific gravity, flash point, solvent

power, etc. Therefore, selection must be based on requirements. Generally

speaking, t! ey must be almost completely volatilized during the drying

process and possess suitable solvent power, causing no precipitation of

"gum" or polymerized oil in the paint or varnish.

Petroleum Spirits (Mineral Spirits ): .Although different fractions from the same petroleum vary greatly in solvent power and while there is little evidence to show what, if any, effect the nature of crude petroleum has <*n the

solvent power of mineral spirits made from it, substitutes prepared from an asphaltic base petroleum (Texas) are believed to have better solvent powers

than those prepared from a paraffin base petroleum (Pennsylvania),

Mineral spirits is not as good a solvent as turpentine, but can be

used in many cases. The only marked difference between products containing

a petroleum distillate, possessing proper volatilization and solvent power,

and those containing turpentine, is found in the flowing or spreading properties. The influence of the thinner on drying, and the nature of dried

film have never been satisfactorily determined.

The recently developed hydrogenated naphthas have proved to be valuable

in utilizing synthetic resins. These naphthas are much better solvents than

the ordinary mineral spirits.

Federal Specificat ion : See TT-T-291, "Thinner; Paint, Volatile Mineral

Spirits" covering that grade of petroleum distillate, known as mineral spirits or petroleum spirits for use in paint, which evaoorates in a manner

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similar to turpentine. In thinning varnishes with mineral spirits it is,

necessary to make sure that the particular varnish "being used will mix

readily with them.

Solvent Naphtha (Coal-Tar Naphtha) ; The distillate of light oil from coaltar, boiling principally between 130°C and l60°C, is a good solvent. It is

extensively used, especially in bituminous paints and four-hour type var- nishes and enamels, to dissolve synthetic resins.,- to increase the solvent

power of petroleum naphthas, and to keep in solution highly blown or kettled

oils. Solvent naphtha is sometimes called l60n benzol.

Composite Vehicle ^

Federal Specification : See TT-T-2 71 , "Thinner; Paint, (For) Semipaste

Paints", covering one grade of a composite vehicle which contains in one liquid, drying oil, drier, and volatile thinner intended for use in cheaper

paints than straight linseed oil paints. It is used for single-coat work,

generally in repainting jobs, and for semipastc paints when the use of

straight linseed oil is not justified,. Although paints made with this com- posite vehicle arc inferior to straight linseed oil paints, they frequently

give good service.

Less Important Volatile Thinners

Benzene (benzol), toluene (toluol), and xylene (xylol), definite com- pounds of lower boiling points than solvent naphtha, also derived from the

light oil of coal-tar, are sometimes used as volatile thinners. Benzene

and toluene are used as volatile thinners particularly in cellulose ester

lac quers.

Grain, denatured, and wood alcohol are used principally in shellac varnishes; amyl acetate, amyl alcohol, butyl acetate, and butyl alcohol in

nitrc-cellulose lacquers.

! Such preparations are sometimes called "Thinning Mixtures for Paint",

and arc also offered under a variety of trade names, such as "Japan Oil",

"Paint Oil", "Linseed Oil Substitute", etc. The term "Linseed Oil Substitute" should not be used for composite vehicle, for while such materials

may have decided merit, they are not substitutes for linseed oil.