John Ripley Freeman.

On the safeguarding of life in theaters; being a study from the standpoint of an engineer online

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the gas supply to the furnace, but they were carried far enough
to prove an endurance more than ample for their purpose as a
shield while the audience^is escaping, and it was plain to all who
witnessed these tests that the sheet steel curtain, protected with
some asbestic material on the fire side, possessed far greater
strength and endurance against fire than the simple asbestos.
The thin sheet of steel, moreover, cut off the view of the fire that
was apparent through the texture of the asbestos canvas.

With care given to the design of the guides and fastenings at
edges and top, so that after it was lowered the curtain could not
be pulled out by warping, buckling, " smoke explosions " or pres-
sure of air, the steel curtains would have a value to the fire under-
writer that no asbestos curtain can possess, and would probably
hold a fire on the stage from entering the auditorium.

The general type of steel proscenium curtain finally adopted
in Chicago and required at all theaters was worked out somewhat
hurriedly, according to the average judgment of the Aldermanic
Committee, in advance of any other tests than the failure of the
Iroquois curtain.

It consists of a light framework of steel angle irons with
corrugated plate about one-sixteenth inch thick on the audi-
torium side, and some asbestic non-conducting material on the
stage side, with an air space of one, two or three inches between.
Where guided only by loops on stationary vertical cables at its
vertical edges, it is required to lap over the edge of the arch
about eight inches. A curtain structure of this kind of the ordi-
nary size weighs from two tons to six tons.

The hanging of most of these Chicago steel curtains would be
improved by more substantial iron channels to hold the edge, and
by the addition of positive down-haul tackle or some arrange-
ment by which the counterweight could be thrown off, for now
the great weight of these curtains is so nearly counterpoised that
it is entirely possible that the excess of air pressure against its
surface of about one thousand square feet may prevent the slight
excess of gravity from lowering it. The Austrian experiments
and the story of some of the eye-witnesses of the Iroquois
disaster indicate the possibility of a strong outward air pressure
from the expanding air.

Finally, regarding fire curtains, it should be said that with
proper smoke vents and complete automatic sprinklers, the
perfection of the curtain becomes of lesser importance.



Theatrical scenery is ordinarily painted on a strong linen canvas
weighing about six and six-tenths ounces per square yard. Heavy
cotton sheeting is sometimes used for the cheaper temporary pro-
ductions. The gauze used for skies and transformation scenes is
of cotton, of texture like mosquito-netting. Frames and battens
and profile backings are of white pine. The canvas is first
stretched on a frame and stiffened by a coat of glue size applied
warm with a broad brash. Next, it receives a priming coat of
whiting and glue size, and is then ready for the scene painter.
The mineral colors used are mixed with water and glue, and many
tests prove that the painted canvas is somewhat less readily com-
bustible than the unpainted, and that the heavier is the coat of
pigment the more flame is retarded.

The fireproofing of scenery canvas and other cloths and fab-
rics has from time to time, during the past fifty years, engaged
the attention of many talented men, and one who now consults
only the articles in books and technical pamphlets is led to
believe that this fireproofing of canvas or cloth can be accom-
plished by brushing the surface over with either one of several
solutions of chemicals.

After reviewing whatever I could find in print, after consult-
ing with several experienced scenic artists, and after making
tests myself, and later enlisting the friendly assistance of several
experienced chemists to carry on independent investigations of
all solutions prominently recommended for the fireproofing or
flame-proofing of fabrics, I regret to conclude:

1st, that the best that is possible in the fireproofing of
scenery is far from satisfactory;

2d, that the petty tests that have satisfied certain distin-
guished chemists are very misleading as guides to what will
happen when the same process is tested on the larger practi-
cal scale;

3d, that the best we can hope to accomplish is to " flame-
proof " a fabric so that it will not ignite from a match,
an electric spark or a gas jet ; or so that if ignited it will not
burst into flame.

This much of protection, little and disappointing as it is, is of
great value and worth all that a good process costs, if it can be


accomplished in practice without injury to fabric or colors; for if
we can thus prevent the little flame from quickly spreading, we
have removed perhaps nine-tenths of the danger of a fire starting
on the stage, but it falls far short of what many have believed
and loudly proclaimed was within easy reach.

Inefficiency of All Methods of Fireproofing Scenery.

Once get the gauze and canvas and pine on the stage enveloped
in flame, everything " fireproof ed " will lurn to total destruction
with substantially as great a rush of flame and suffocating smoke
as with the untreated material. Indeed, the chemicals may make
the fumes worse.

After having investigated the question of fireproofing the
scenery faithfully, probably with greater thoroughness than has
ever been done heretofore, I am led to believe that we must
after all rely on the safeguards of the engineer rather than those
of the chemist, for the safeguarding of human life in theaters.

The efficient fireproofing of the great quantity of white pine
used in frames, battens and profiles (eight thousand square feet
in the case of the Iroquois) appears to be a practical impossibility.
The eleven miles of manila ropes cannot be "flame-proofed"
without too great a sacrifice of their strength.

New Tests and the Theory of Action of " Fireproofing "


Distrusting the ordinary test of trying to ignite a small strip
of the treated cloth with a match or gas flame, early in these
studies I took about one-fourth a square yard of cloth treated
with phosphate of ammonia, which is the most efficient fire re-
tardant of all the half hundred chemicals and mixtures yet rec-
ommended, and hanging it in sheets half an inch apart within a
piece of common stove pipe two feet long, lined with a sheet of
asbestos in order to check the loss of heat by absorption in the
cold metal, lighting it at the bottom with a little wad of u excel-
sior" wood shavings, I saw this "most perfectly fireproof ed
cloth" disappear with a rush of flame in forty seconds.

The difference in the results of a test of a single strip over a
gas flame and a series of parallel sheets hung near together within
a chamber is that in the second case we confine the radiant heat
and the distilled combustible gases very much as they would be


confined in the closely hung sheets of scenery over the stage
(see Figs. 1 and 2).

It is almost inconceivable that any of the various solutions used
for fireproofing canvas or wood could so change the cellulose,
gums and resins, of which these mainly consist, as to prevent
their destructive distillation with the evolution of the same vol-
ume of inflammable gas, much like ordinary illuminating gas,
that they ordinarily give out when heated to the char point.

We may find it slow work to light the wet twigs and green
wood for our camp fire, but once well started, they burn furi-
ously. The best fireproofing of fabrics amounts to about the
same as substituting a fabric of wool for one of flax or cotton.
Woolen mills by fifty years' experience are no better insurance
risks than cotton mills.

Our various tests, interpreted from the scientific point of view,
indicate that about all that we can hope for from the application
of " fireproofing" chemicals is as follows:

1st, the destructive distillation of the chemical may keep
the surface of the cloth near the applied flame bathed for a
few seconds in a thin film of steam or inert gas, arising from
the distillation of the microscopic quantity of the chemical
lodged in the fabric, thus keeping the oxygen of the air
away from the carbon for a moment.

2d, the dissociation or distillation of this little quantity
of the chemical absorbs a little of the heat applied or

3d, the chemical used may have a non- volatile base which
will fuse and cover the surface of the'combustible carbon
with a glassy film that, although exceedingly thin, will keep
this carbon beyond reach of the oxygen of the air. This may
perhaps lock up from twenty-five per cent, to fifty per cent,
of the heat-giving content of the fiber.

I have already intimated that phosphate of ammonia has given
the best record in fire-retardant quality of any of the many chem-
icals and mixtures tested. Theoretically, we should expect it to
do so, for its chemistry fulfils the above conditions. First, it has a
little tendency to gather dampness, and to dry this out absorbs a
little heat. Next, as the heat" rises, ammonia is given off, and the
film of this repels the oxygen of the air. When the ammo-


nia is gone we have left the otho phosphoric acid which in liquid
form covers the surface and preserves it from oxidation under
increasing heat. At 300 to 400 degrees Fahrenheit this decom-
poses, giving off water; at higher temperatures, it gives off its
remaining water. In all of this dissociation it absorbs some heat
until we have left, at full red heat, fused meta-phosphoric acid as
a liquid film surrounding the fixed carbon remaining from the de-
structive distillation.

On the other hand, the phosphate of ammonia has its disadvan-
tages. A manufacturing chemist, perhaps of widest experience
of any in this country in the practical chemistry of the phos-
phates, warns me that for its best efficiency it must be applied
in a strong or saturated solution, but if very strong, it may in
time disastrously affect the strength of the fiber, that it is some-
what deliquescent, has a tendency to develop fungous growth,
that in time it may part with a portion of its ammonia, becoming
the acid ammonium phosphate which has a tendency in presence
of moisture to attack metals, while in a warm atmosphere the free
phosphoric acid attacks some colors.

The foregoing cautions by my friend, the chemist, were derived
from experience on other material than stage scenery, and we
shall soon have plenty practical experience to show if phosphate
of ammonia is injurious to scenery, under the practical condi-
tions of use, for this has been used during the past year and a
half more than any other substance to meet the enforcement of
the laws of certain cities requiring all stage scenery to be fire-
proofed. The diluteness of the solution that has been applied in
some instances within my observation will tend to lessen its in-
jurious qualities in the same degree that it weakens its flame-
proofing, and the tendency of any antipyrine to promote mildew
in damp atmospheres can probably be prevented by adding some
antiseptic or germicide to the solution.

History and Practice of Fireproofiny Canvas.

After each of the great historic theater fires that have occurred
since the science of chemistry was born, this subject of fireproofing
cloth has been studied by chemists of eminence, and nearly all of
the chemicals and compoundsr ecently brought forward by scenic
artists and dealers in painters' supplies are the same that have
been recommended over and over again for the past fifty years.


The tests made from time to time for proving their efficiency
have not copied practical conditions.

It is said that fifty years ago, after a serious fire in the Berlin
Opera House, it tvas made the custom to soak the scenery canvas
in a strong solution of alum; nearly fifty years ago a Parisian
chemist carefully examined the subject of fireproofing scenery,
and orders are said to have been issued that all stage scenery be
impregnated with silicate of soda. Fifty years ago the value of
phosphate of ammonia was recognized as an antipyrine. Forty-
five years ago an elaborate series of researches was reported to
the British Association for the Advancement of Science, embrac-
ing a great range of chemicals, with many tests for determining
the most effective strength of solution to be applied. Nearly
thirty years ago, after the Brooklyn Theater horror, some of the
scenery in Wallack's Theatre in New York is said to have been
fireproof ed with tungstate of soda, and the well-known New
York chemist, Dr. R. Ogden Doremus, called the attention of
American theater managers to phosphate of ammonia. More
than twenty-five years ago a committee of the British House of
Commons took testimony on this matter of fireproofing scenery,
and the manager of the Criterion Theater testified that he regu-
larly used sodium tungstate in the preparation of new scenery.
Curiously, our recent tests fail to show any great virtue in sodium
tungstate as an antipyrine. Twenty years ago the London So-
ciety of Arts reported on fireproofing of stage scenery and re-
ported that the scenery in nearly all London theaters was treated
with some fire retardant preparation.

Twenty years ago a committee of the Franklin Institute of
Philadelphia studied and reported on this subject, recommending
sundry chemicals.

Eleven years ago Prof. ^Thomas H. Norton devoted to this
subject his presidential address before the Section of Chemistry
in the American Association for the Advancement of Science at
the Brooklyn meeting, and made it appear that fireproofing of
fabrics was easy.

Nevertheless, it is probable there was at the time of the Iro-
quois fire hardly a piece of scenery on a theater stage in the
United States or England, or anywhere else, that had been sub-
jected to fireproofing treatment.

The veteran manager, John B. Shoeffel, tells me that from his
experience with the French and English made scenery used in


the American tours of Bernhardt, Eejane, Mounet-Sully, Coque-
lin, Mary Anderson, Irving and others under his management,
it is his confident belief that none of it was fireproofed. His
experienced stage mechanic, William J. Kelly, confirms this
and says further, that according to his personal experience on the
stage of several London theaters, none of their scenery was fire-
proofed. The eminent scenic artist, Walter Barrage, of Chicago,
tells me that through personal experience in England and confer-
ence with scene painters from the Continent, he has found there
was no general use in Europe of fire retardant solutions in the
preparations of scenery.

A year ago Mr. E. O. Sachs, Secretary of the British Eire
Prevention Committee, wrote me that there was then no re-
quirement for the fireproofing of scenery by chemical solutions
in the English law, and in his compilation of the Building Laws
of European cities, in Yienna alone, do we find mention of fire-
proofing of scenery, and there very vaguely.

Thus, notwithstanding widespread belief, backed by much
eminent authority that scenery could be readily flame- proofed, it
has not been done.

~Wliy Stage Scenery Has Not Been Flame-proofed.
In brief, the reasons are:

1st, it adds to the cost by an amount that may be estimated
at from $250 to $500 for the average five-act drama, having
25,000 square feet of canvas, and adds two or three times this
cost for a great spectacular piece. Seldom would flame-
proofing add more than five per cent, or ten per cent, to the
cost of an outfit of scenery.

2d, there is a fear that most of the fireproofing chemicals
injure the strength of the canvas.

3d, the scenic artists have feared the effect on their deli-
cate colors.

4th, some of the chemicals proposed tend to rust and
loosen the iron fastenings and tacks.

5th, most of the stage scenery in existence is traveling
around the country, stopping only a brief time in one city,
and it is a tedious matter for the local authorities to make
certain that it has been fireproofed.

6th, the appalling theater catastrophes have come almost a


generation apart. The people and the officials have short
memories for their lessons. Inspectors become easy about
special laws which, passed under pressure of a great calam-
ity, soon become dead letters.

7th, the general public is thoughtless and indifferent and
runs its chance.

Therefore, at the present time, although since the Iroquois
fireproofing has become a general rule, remembering the likeli-
hood that in future as in the past the fireproofing of scenery will
become neglected, we may all the more emphasize the importance
of the perfected automatic smoke vent and of the automatic
sprinkler and the other obvious safeguards.

A New Investigation of the Fireproofing of Fabrics.

After some preliminary trials, with the assistance of the
chemical engineer of the Inspection Department of the Factory
Mutual Insurance Companies and conferences with the experienced
scenic artists, Burrage of Chicago and Story of Boston, and after
reviewing the probable effect of various solutions upon the fabrics
and upon the ordinary colors used by the scenic artist with some of
my personal friends who were of wide experience as chemists of
textile factories and chemical works, I enlisted the ingenuity of
my friend, Mr. George C. Whipple, Consulting Engineer, Director
of the Mt. Prospect Laboratory in Brooklyn, and of Mr. Irving
W. Fay, Professor of Chemistry in the Brooklyn Polytechnic
Institute, in the hope that starting with the theory of the suc-
cessful action of ammonium phosphate^ as stated above, we
could find some substance of equal value as an antipyrine that
would be less likely to injure fabric or colors. Sundry theaters
and scenic studios were visited by Mr. Whipple to learn the prac-
tical conditions. The bibliography of the subject was again thor-
oughly reviewed. Standard methods for testing the comparative
efficiency were worked out, and tests were made with substan-
tially all of the substances that had been recommended by good

Nothing was found better than, or so efficient as, the phos-
phate of ammonia, known to be efficient for the past fifty years.
Nothing was found that would prevent the instant burning with
a rush of flame when the test was made with a strong Haze on
closely hung sheets of canvas, but many substances were found


that would make gauze and canvas proof against ignition Jby a
match, flame, gas jet, a cigarette or an electric spark.

Some Tests of Effect of Fire-proofing Solutions upon Colors.

In my Boston tests the results of sundry solutions, after from
one month to one and one-half years' time, upon canvas sized and
painted in the ordinary way with the ordinary colors of the
scenic artist's palette, was as given in Tables 4 and 5 (pages
127 and 128), which are representative selections from eight
large test sheets :

These eight samples were prepared in the studio of Mr. Story,
a well-known scenic artist of Boston, under the supervision of Mr.
L. K. Davis, chemical engineer of our Inspection Department.
Sheets of ordinary linen scenery canvas and also sheets of wide
cotton such as used for scene painting, each about seven feet
square, were painted with broad flat stripes of the colors found
commonly in the scene painter's palette put on by an experi-
enced artist in the ordinary manner. After these strips of
color were thoroughly dry other broad stripes, crosswise to the
first, were applied, consisting of one stripe each of the various
chemical solutions which at that time were most prominently
commended for firep roofing scenery. This checker-board pattern
thus permitted about 180 simultaneous tests of color and chemical
on each of our eight large canvas sheets, or more than 1,000 in all.

Solutions of different strength were tried on different sheets,
15 per cent, and 25 per cent, respectively, and the further ex-
periment was made of first applying a strong solution of each
chemical to the canvas before it was sized and painted. This
gave much better results and far less discoloration than when
the canvas was flame-proofed after it had been sized and painted.

The reason for the less discoloration plainly is that the chemi-
cal penetrates the fiber more easily before it has been sized,
and that the sizing prior to the painting locks it in and puts it
into less intimate contact with the pigment.

I found, in every case, that the phosphate of ammonia affected
many of the colors, and that the ammonium chloride and the
strong solution of " fireproofine " were very injurious.

The treated canvas when dry and shaken gave off a dust from
the chemicals.

To independently verify and extend the above tests that the



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chemical engineer of our Inspection Department had made in a
Boston scenic studio, Messrs. Whipple and Fay tested about thirty-
five colors and shades by painting these colors in stripes on a sheet
of canvas, and there crossing them with stripes of the various fire-
proofing solutions. In the brief tests by Whipple and Fay no
colors were found affected by the solutions commonly used save
the cobalt blues and the delicate violets, thus differing somewhat
from the results of my previous tests at Boston in which I found
many of the standard scene painters' colors affected by phosphate
of ammonia and ammonium chloride to the extent of changing
the shade or tint, and in extreme cases destroying the color, and
had found that samples of painted scenery treated with a trade
preparation called " fireproofine " became marred by a dusty
white efflorescence.

Possibly this efflorescence is to some extent a matter of
manipulation, and the decision about injury to colors, as sug-
gested regarding the promotion of mildew, had best be made
after we are all possessed of the result of a few years' experience
with the present legal requirements for fire-proofing scenery in

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Online LibraryJohn Ripley FreemanOn the safeguarding of life in theaters; being a study from the standpoint of an engineer → online text (page 5 of 8)