Wick compositions for incendiary devices

A wick composition for incendiary devices is disclosed which enables an improved and controlled burn rate. The wick composition comprises: PA1 (a) about 25 to about 75 weight percent of a nitrate compound selected from the group consisting of cellulose nitrate, cellulose trinitrate, polyvinyl nitrate, and ammonium nitrate; PA1 (b) a nitrate stabilizer; and PA1 (c) a wick or string material.

FIELD OF THE INVENTION 
This invention relates to improved wick compositions for incendiary devices 
such as candles. More particularly, this invention relates to wick 
compositions for incendiary devices which enable improved and controlled 
burn rates. 
BACKGROUND OF THE INVENTION 
Compositions for incendiary devices are well known in the art. For example, 
in McCormick, U.S. Pat. No. 224,203, a lamp wick saturated in a solution 
of nitrate of potash and alum is disclosed. In Haase, U.S. Pat. No. 
807,553, a method is disclosed for facilitating lighting of candles and 
tapers made of stearin, wax, paraffin or other suitable material. The 
method comprises dipping the free end of the wick material, which will not 
be embedded in the candle substance, in a solution of celluloid in 
acetone. 
In Grosvenor et al., U.S. Pat. No. 1,430,543, a lighter wick is disclosed 
for cigars, cigarettes, and pipes in which a suitable "tow wick" is made 
with an adjusted quality and quantity of fat material. An oxidizing agent 
which may include nitrates and chlorates is disclosed to promote 
combustion. 
In Fox et al., U.S. Pat. No. 3,940,233, a lead-free candle composition is 
disclosed which comprises a combustible wick composition comprising a 
combustible wick and a stiffening agent. The stiffening agent comprises a 
wax-insoluble polymer or copolymer having a Vicat softening point of at 
least 2.5.degree. C. higher than the melting point of the candle wax. 
Examples of suitable stiffening agents mentioned include polyacrylates, 
polymethacrylates, polystyrenes, styrene-acrylate copolymers, 
styrene-methacrylate copolymers, nitrocellulose and derivatives thereof. 
Polymethylmethacrylate and polystyrene are mentioned as being excellently 
suited as the stiffening agents. The Fox et al. candle compositions 
comprise about 75-95 weight percent of a wicking material and 5-25 weight 
percent of a stiffening agent. 
The problem with many of the prior art compositions for incendiary devices 
is that the compositions result in the emission of harmful or noxious 
gases. Further, many prior art compositions do not enable a controlled 
burning of the wick of the candle or other incendiary device. It would 
therefore be advantageous to provide a composition for incendiary devices 
which would burn completely at a controlled burn rate with no harmful 
gases being emitted during or after burning. 
SUMMARY OF THE INVENTION 
The invention comprises a wick composition for incendiary devices which 
enables an improved and controlled burn rate comprising: 
(a) about 25 to about 75 weight percent of a nitrate compound selected from 
the group consisting of cellulose nitrate, cellulose trinitrate, polyvinyl 
nitrate, and ammonium nitrate; 
(b) a nitrate stabilizer; and 
(c) a wick or string material. 
The wick or string material may comprise linen, rayon, cotton, or cellulose 
or mixtures thereof. Optionally, the wick compositions may additionally 
comprise a material to give the wick composition pliability or flexibility 
which may be desirable depending on the application of the wick 
composition. Such pliable materials include naphthalene, camphor, or other 
suitable cross-linked polymers such as polyethylene. The invention further 
comprises methods of making such wick compositions for incendiary devices. 
The wick compositions of the invention are especially suitable for lighting 
an incendiary device comprising a series of candles such as birthday cake 
candles linked together in series by the wick composition. 
DETAILED DESCRIPTION OF THE INVENTION 
The wick compositions of the invention for incendiary devices having 
improved and controlled burn rates comprise: (a) a nitrate compound 
selected from the group consisting of cellulose nitrate, cellulose 
trinitrate, polyvinyl nitrate, and ammonium nitrate; (b) a nitrate 
stabilizer, and (c) a wick or string material. The wick or string material 
preferably comprises rayon, linen, cotton, cellulose, or a mixture 
thereof. Optionally, a pliable material such as camphor, naphthalene, or a 
suitable cross-linked polymer such as polyethylene may be added if needed 
to make the wick composition more pliable or flexible. 
The nitrate compound contained in the wick compositions of the invention is 
selected from the group consisting of cellulose nitrate, cellulose 
trinitrate, polyvinyl nitrate, and ammonium nitrate, such as a 
commercially available nitrocellulose sold under the designation Hercules 
Nitrocellulose RS18-25-SEC, available from Hercules Chemical Co., 
Wilmington, Del. The nitrate compound comprises about 25 to about 75 
weight percent of the wick composition, and preferably about 40 to about 
70 weight percent of the wick composition. Also, preferably the nitrate 
compound comprises about 12 to about 13.5% nitrogen. 
The nitrate stabilizer is preferably selected from the group consisting of 
dibutyl phthalate, diphenylamine, and ethyl centralite. Preferably the 
nitrate stabilizer comprises ethyl centralite such as an ethyl centralite 
which is commercially available under the designation 
1,3-diethyl-1,3-diphenylurea from Aldrich Chemical Company, Milwaukee, 
Wis. The nitrate stabilizer preferably comprises about 0.1 to about 5.0 
weight percent of the composition, and most preferably comprises about 0.1 
to about 1.0 weight percent of the composition. 
The wick composition of the invention further comprises a wick or string 
material. Preferably the wick or string material is selected from the 
group consisting of linen, rayon, cotton, cellulose or mixtures thereof. 
Most preferably, the wick or string material comprises linen, rayon, or a 
mixture thereof. In one preferred embodiment, the wick composition used in 
the invention comprises a multi-filament linen or rayon yarn. Examples of 
wick or string material according to the invention include but are not 
limited to multi-filament rayon yarns available from North American Rayon 
Corporation, Elizabethton, Tenn. Two such yarns are sold under 
manufacturing codes 4321 and 4324, and both have a denier size of about 
150, about 60 filaments per yarn, and about 3 turns or twists per yarn. 
Another example of a suitable wick or string material according to the 
invention is a multi-filament rayon yarn manufactured by Dixie Yarns, Inc. 
of Gastonia, N.C. sold under the manufacturing code 12/2 Rayon Lot No. 
885SJ. This yarn has a denier size of 60, about 738 fibers per 
cross-section, and a twist of ply 9.0. The wick or string material 
comprises about 25 to about 75 weight percent of the wick composition, and 
preferably about 30 to about 60 weight percent of the wick composition. 
The wick compositions of the invention are made by forming a nitrate 
solution by dissolving the nitrate compound in a suitable solvent and 
mixing the dissolved nitrate compound with a nitrate stabilizer. The wick 
or string material is then passed through the nitrate solution to form a 
wick material coated and impregnated with the nitrate solution. The 
nitrate solution is then dried. 
For example, the nitrate compound and the nitrate stabilizer are dissolved 
in a suitable solvent for the nitrate compound. Such solvents are well 
known in the art and include, for example, ethyl acetate, alcohol/ether, 
acetone, ethylene glycol acetate, methoxybutanol acetate ketones, 
methanol, or an inorganic hydroxide. The dissolved nitrate compound is 
then mixed with a nitrate stabilizer to form a nitrate solution. The 
nitrate solution is then inserted or impregnated into the wick or string 
material by any suitable method such as by passing the wick or string 
material through the nitrate solution by methods which are well known in 
the art. Such methods include, for example, placing the nitrate solution 
in a coating chamber and pulling the string or wick material through the 
chamber. Alternatively, the string may be dipped into the nitrate 
solution. The nitrate solution may be worked and impregnated into the 
string or wick material by spreading the fibers or monofilaments of the 
string or wick material by conventional means and pulling the string or 
wick material through the nitrate solution. Such impregnation methods are 
described, for example, in U.S. Pat. Nos. 3,042,570 and 5,019,450, 
incorporated herein by reference, which relate to impregnation of fiber 
reinforcing materials such as glass fibers with thermoplastic resins for 
long fiber thermoplastics. 
The compositions of the invention may additionally comprise a pliable 
material such as naphthalene, camphor, or other suitable cross-linked 
polymers such as polyethylene. The following examples further illustrate 
the wick compositions of the invention.

EXAMPLE 1 
A wick composition was prepared comprising 25.0 wt. % cellulose nitrate 
(12% nitrogen), 0.3 wt. % ethyl centralite as a stabilizer, and 74.7 wt. % 
of either of the North American Rayon multi-filament rayon yarn 4321 or 
4324. The cellulose nitrate was first mixed with acetone until it was in 
liquid phase and mixed with the ethyl centralite. The rayon wick material 
was then passed through the liquid cellulose nitrate solution and dried 
either by forced air (convective) or vacuum drying at 80.degree. C. The 
burn rate (inch/second) of this wick composition was approximately 0.42. 
EXAMPLE 2 
A wick composition was made according to Example 1 except that 50.0 wt. % 
cellulose nitrate (12% nitrogen), 0.5 wt. % ethyl centralite, 48.5 wt. % 
of a multi-filament yarn described in Example 1, and 1.0 wt. % naphthalene 
was used. The burn rate (inch/second) of this composition was 
approximately 0.93. 
EXAMPLE 3 
A wick composition was made according to Example 1 except that 74.0 wt. % 
cellulose nitrate (12% nitrogen), 0.7 wt. % ethyl centralite, and 25.3 wt. 
% multi-filament rayon yarn described in Example 1 was used. The burn rate 
(inch/second) of this composition was approximately 1.30. 
As can be seen in Table I below, the burn rate of the compositions of the 
invention can be controlled by the amount of nitrate compound added to the 
wick material. In Table I, all wick compositions were made according to 
Example 1, and only the amount of cellulose nitrate to the amount of wick 
material was varied. 
TABLE I 
______________________________________ 
% Cellulose Nitrate 
Wick Burn Rate 
in Coated Wick (inch/sec) 
______________________________________ 
26.0 0.42 
58.8 0.93 
68.0 1.10 
74.0 1.30 
78.0 1.10 
______________________________________ 
EXAMPLE 4 
An incendiary device comprising a group of birthday candles linked together 
in series was prepared from the wick composition of Example 2. The 
standard wicks of about thirty-five candles were attached to a suitable 
length of the wick composition so that all standard candle wicks were 
linked to one another in a series, each candle being a distance of about 
one to three inches apart. The attachment of the wick composition to the 
standard candle wicks was made by solvent gluing each standard candle wick 
to the wick composition with the wick composition solvent (acetone). 
However, attachment of the wick composition to the standard candle wicks 
can be accomplished by any other suitable means such as with a suitable 
adhesive or by ultrasonic welding. The series of birthday candles were lit 
by simply igniting one end of the wick composition attached to the wick of 
the first or last candle in the series. 
The advantages of the wick compositions for incendiary devices of the 
invention include that the incendiary devices using the wick compositions 
of the invention, when lit, will burn completely without residue and will 
produce no harmful gases. Further, the incendiary devices made from the 
compositions of the invention may be used to light a single incendiary 
device such as a candle, or may be used in series to light multiple 
candles or incendiary devices. For example, the compositions of the 
invention can be used to ignite multiple birthday or holiday candles 
linked together in a series by said wick composition. The speed of burning 
can be controlled as described above, depending on the amount of nitrate 
compound used.