E. 0’HARAr
RADIUM LUMINOUS ARTICLE» AND METHOD OF PRODUCING SAME.
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APPLlCATlON FILED DEC. 26, 1919.
1,364,950.
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Patented, Jan- 11, 1921
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UNITED sTAres_PATENT 'OFFICE.
ELIOT O’HARA, OF WALTHAM, MASSACHUSETTS.
RADIUM LUMLNOUS ARTICLE AND METHOD OF PRODUCING SAME.
Speci?cation of Letters Patent.
1,364,950.
Application ?led December 26, 1919.
To all whom it may concern:
Be it known that I, ELIOT O’HARA, a citi
zen of the United States, residing at Wal
Patented Jan. 11, 1921.
Serial No. 347.591.
from the following description when taken ‘
in connection with the accompanying draw
lng's, and the novel features thereof will be
polnted out and clearly de?ned in the claims
chusetts, have invented a certain new and at the close of this specification.
useful Improvement in Radium Luminous
The drawing is a view showing on a
Articles and Methods of Producing Same, greatly exaggerated scale a portion of an
of which the following is a speci?cation, zirticle treated in accordance with the inven
tham, county of Middlesex, State of Massa
reference being had therein to the accom
10' panying drawings.
15
to be treated is ?rst coated with opaque en
dium luminous material inorder to render
ing 1s then ?red on as is commonly done
65
amel 2 which contains no lead. This coat
the compound usually contains disintegrate rial. radium luminous compound, etc. One
through the bombardment of the alpha rays kind of radium luminous compound suitable
of the radium. Furthermore the exposed for such purposes consists of crystallized
radium luminous surface collects dust and zinc sul?d mixed in proper proportions with
dirt. Attempts have been made to protect radlum bromid; another suitable compound
the radium luminous surface by glazing it. conslsts of zinc sul?d mixed with mesotho
The ordinary glaze however, contains lead rlum. A suitable proportion is two parts of
which destroys or at least diminishes the
luminosity of the coating or at any rate
30
‘
In practising my invention the article 1
self-luminous certain ?gures or other special with any enamel name-plate, dial or sign.
markings on the article. As heretofore done, . After the coating has been ?red on there
however, the self-luminous coating is re is applled to the portions which are intend
moved by the action of the weather, such as ed to be made luminous, a coating ofllumi
moisture or ice, or by cleaning agents. nous powder 3 which is commercially sold
"Also as heretofore done, the crystals which under the name of radium luminous mate
20 -
25
1on.
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It has heretofore been common to coat
surfaces of dials or other articles with ra
60
70
75
80
radlum bromid or mesothorium to ten thou
sand parts of zinc sul?d, but these propor
tlons may be varied considerably if desired.
prevents the light from the radium lumi
nous material from showing in substantially There are, however, numerous other com
85
its full strength through the glaze. Some pounds which may be employed with ‘good
results and which contain radio-active and
protect the luminous coating have been by radio-responsive material which will stand
of the previous methods of attempting to
35
covering the surface with sheets of glass or
mica, or coating it with lacquer or varnish.
None of these methods have so far as I am
aware been successful in accomplishing the
result desired, namely of fully protecting
the radium luminous compound and at the
40 same time in not materially diminishing the
_ luminosity, nor have they delayed disinte
gration of the crystals.
45
50
the temperature of glazing, and I consider
90
any such compound as coming within the
scope of my invention.
In order to cause
the luminous powder to adhere tothe por
tion which is to be rendered luminous there
is preferably employed as a vehicle or adhe 96
sive, a gum or other adhesive material which
will turn to a gas and leave as small as pos
sible residue in the heat afterward to be
The object of the present invention is to applied. I have successfully used for this
provide the radium luminous surface with purpose a very ?ne solution of gum arabic 100
a protective coating which will permit the in water, or a very thin solution of gun
light emanating from the radium luminous cotton in amylacetate or acetone, also Venice
material to pass through the coating in sub turpentine in oil of thyme or alcohol, but
stantially its full strength and which shall other materials may be used 'and the proc
protect the radium luminous material ess is not con?ned to any one of these.
105
against disintegration and render it weather
After the application of the luminous I‘
proof and of such characterthat it will not powder in the manner above speci?ed, the
readily collect dust and dirt, and which luminous powder and its vehicle by which
can be easily cleaned without detriment to it is applied to the markings are allowed to
the radium luminous surface or to the pro
55 tective coating.
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dry thoroughly. This usually takes from
three hours to forty-eight hours, depending
The invention will be fully understood on the adhesive or vehicle used. Whatever»
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1,364,950
2
the length of time required it should be al
lowed to dry thoroughly.
After it has thoroughly dried I sift on
the face of the article to be treated a thin
coat or ?lm of ?ux, sometimes commercially
10
luminous compound was applied to the arti
55
cle will have substantially disappeared.
What I claim is 1-
1. An article having an opaque enamel
coating, radium luminous markings applied
known as glaze or fondant, having previ ' to the surface of said enamel coating, and a
ously reduced this flux to powder of suitable transparent vitri?ed coating over said lumi
degree of ?neness. I have successfuly used nous markings.
2. The method of giving a transparent
a size grain which will pass through number
60
markings on an article, consisting of treat
ing the face of the article with a thin coat
65
thirty-eight bolting cloth, but it may be protective coating to radium luminous
coarser or ?ner without having a detri
mental effect on the result of the process.
It is quite important that in selecting the of finely powdered ?ux, which is free from
lead and consequently will not discolor the
tains no lead. Any one of certain types of radium compound, and allowing the same
potash-lime glass which is free from lead to thoroughly dry, then vitrifying the coat
makes a suitable ?ux or glaze for this pur of ?ux by placing the article to be treated
?ux a material should be used which con—
15
70
in a mu?le furnace and allowing the same to
remain
in the furnace for a period of time
cording to the followilrilg formula :—100 S02, ‘
20 34 K2CO3, l5 CaO2 2 and .33 MnO2, or at a high temperature.
3. The method of treating an article to
other formulae given in Thorpe’s Dictionary
pose; such for instance, as a glass made ac~
25
of Applied Chemistry under the caption of produce a radium luminous marking with
Potash lime glass. I do not intend to limit transparent protective coating consisting of
myself, however, to the particular ?ux above coating the article with opaque enamel
mentioned or those referred to, as there are which contains no lead, then ?ring the coat
numerous other leadless ?uxes suitable for ed article, then applying to the article ra
the purpose.
Those above mentioned are
80
dium luminous material, and making the
merely given as illustrative specimens which same adhesive to the portions which are to
are suitable. As an alternative to sifting on
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latter method is used the coat of flux should
35
be made luminous, using as a vehicle an ad
a coating of dry powder the powder can be hesive of a character which will turn to gas
mixed with water or volatile oil and spread when heat is applied, then applying to the
on the article with an air brush. If the face of the article containing the markings
and previous coatings a thin coat of flux
be allowed to dry thoroughly before the which has previously been reduced to a
powder, then vitrifying the coat of ?ux in a
next operation.
After the coat of flux is thoroughly dry it mu?le furnace at a high temperature.
should be ?red or vitri?ed in any suitable
4. An article having a radium luminous
manner. The preferred method is to place
marking thereon provided with a transpar~
ent protective coating consisting of a flux
the article in a muf?e furnace for a suitable
85
90
length of time. The space inside the mu?ie free from lead and vitrified on the radium
should be kept at a temperature just su?i
'cient to fuse ‘or vitrify the ?ux. I have
found in practice a temperature of 1000‘’. to
1200° Fahrenheit for a period of from two
45 to four minutes to be very satisfactory, but
good results are possible with other tem
50
luminous surface.
5. An article having a radium luminous
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marking thereon, and a transparent protec
tive coating therefor consisting of a ?ux
free from lead and vitri?ed on the radium
peratures and with other periods of time
100
luminous surface.
6. An article having a coating of opaque
in the muffle.
enamel free from lead, a radium luminous
~
This produces a transparent, hard glazed marking thereon, and a transparent protec
coat 4 whichv will allow the light from the tive coating therefor consisting of a flux free
radium luminous compound 3 to show in
substantially‘full strength through the glaze
and will be very durable. The adhesive
‘substance which was employed when the
from lead and vitri?ed on the radium lumi 105
nous surface at a high temperature.
In testimony whereof I affix m signature.
ELIOT ’HARA.