Methods for increasing a camouflaging effect and articles so produced

Methods and articles so produced for increasing the camouflaging effect of any camouflaging pattern, the invention relates to the coating of at least portions of a camouflaging pattern disposed on an article with a material capable of assuming different chromic states at different ambient light levels. Materials employed to produce color changes in the camouflaging pattern include light and/or heat sensitive dyes and/or inks and particularly photochromic materials capable of reversible color changes. At least portions of camouflaging patterns modified according to the invention change color, such as from a color in the original camouflaging pattern to a different color or from a first shade of a given color to a second shade of that same color, on exposure to sunlight either of a more direct nature or a greater intensity, the color change being reversed in whole or in part by a return of ambient light conditions toward or to a given set of original light conditions. Color changes can also be from a clear "no color" state to a colored state. Since lighting conditions, especially direct sunlight, can cause thermal changes, materials capable of reversible alteration in chromic state due to heat changes also find utility in the methods of the invention.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates generally to methods for camouflaging articles 
including articles of clothing and the like and to camouflaging patterns, 
the invention relating particularly to methods and articles so produced 
for increasing the camouflaging effect of a camouflaging pattern by 
changing the chromic state of materials forming at least some of the 
camouflaging pattern on exposure to changing ambient light conditions. 
2. Description of the Prior Art 
Camouflage is an art unintentionally but advantageously employed in nature 
to conceal by pattern and/or color. Mankind learned basic camouflaging 
techniques from natural sources long prior to recorded history in order to 
conceal human beings, their possessions and even dwellings from human 
enemies as well as from animals being hunted or possibly hunting human 
beings. In more recent times, camouflage has been commonly employed in 
sport hunting and in military situations, these differing applications 
sharing a common intent of concealing people, clothing, armament and other 
accessories through the use of patterns and color which cause the 
concealed entities to merge with a given background. Camouflaging patterns 
presently in use vary widely but usually involve representations of 
natural structure taken from a given environment with which the hunter 
intends to blend. Such structure includes vegetative materials in 
particular, whether as individual leaves, stems, branches or the like or 
vegetative groupings which can be representative of one or more bushes, 
trees, etc. These patterns are often colored with a number of different 
colors depending upon the background with which a particular pattern is 
intended to blend. Such patterns are typically formed by the screening of 
individual colors in succession on a substrate such as a textile 
substrate. Even when a variety of colors are employed in an original 
printed camouflaging pattern of this kind, the color intensity and color 
type does not change to produce an improved camouflaging effect when the 
camouflaging pattern is exposed to increased ambient light conditions such 
as occurs, for example, when the sun comes out from behind a cloud. In 
prior art camouflaging patterns, the reflective capacities or capabilities 
of the colors forming portions of the camouflaging pattern do not change 
since a given color in the camouflaging pattern remains that color 
regardless of ambient lighting conditions. Given this characteristic of 
prior art camouflaging patterns, it is readily seen that such prior art 
patterns do not allow for changes in the colors forming the pattern when 
the pattern is exposed to increased lighting levels such as are primarily 
due to changing sunlight conditions. Even more clearly, prior art 
camouflaging patterns do not provide for changes in the patterns 
themselves when the pattern is exposed to increasing levels of sunlight. 
Essentially, except for possible minor changes in color shading brought 
about by reflectivity only when a prior art camouflaging pattern is 
exposed to increased ambient light levels, the prior art does not 
encompass in its teachings a change in a camouflaging effect, much less an 
improvement in a camouflaging effect brought about by differing ambient 
light conditions and particularly sunlight exposure levels. In effect, 
prior art camouflaging patterns remain essentially the same regardless of 
sunlight intensity. 
Photochromic materials are well known in a variety of arts and include 
light and/or heat sensitive dyes and/or inks both inorganic and organic 
including polymeric materials, microencapsulated materials and paints 
inter alia, which materials can be solvated in water-based or other 
solvents. A characteristic common to photochromic materials is the ability 
to change chromic state between at least two different light levels. A 
chromic state is that color condition, including a colorless condition, 
which exists at a given light level or levels. As an example, a 
photochromic dye can be essentially colorless at ambient light conditions 
such as would exist indoors out of direct sunlight but would change to a 
colored state when exposed to increased ambient lighting conditions such 
as direct sunlight and/or when exposed to increased heat levels. 
Photochromic dyes such as "chromasome inks" are particularly available 
which exhibit colorless chromic states at ambient lighting conditions such 
as would exist indoors out of direct sunlight but which change chromic 
state to a colored condition when exposed to direct sunlight, these dye 
materials having previously been used in articles of apparel such as "T" 
shirts and the like to produce a colored pattern on the article of 
clothing when the wearer is in direct sunlight but which "disappears" when 
the article of apparel is worn indoors in normal indoor ambient light 
conditions. As such, the prior utility of photochromic dyes and inks of 
this type has been to produce a highly visible and recognizable pattern on 
an article of apparel when that article of apparel is exposed to direct 
sunlight, such articles of apparel and the patterns thus formed thereon 
being the literal opposite of camouflage since such prior art patterns are 
intended to be seen. 
The present invention intends the provision of methods and articles 
produced by the methods for increasing the camouflaging effect of any 
camouflaging pattern by virtue of coating of at least portions of the 
camouflaging pattern with a photochromic material capable of different 
chromic states under differing ambient light levels. The camouflaging 
patterns produced according to the invention are intended to change color 
and even shape due to color change and when the patterns are exposed to 
differing ambient light levels and particularly to direct sunlight as 
opposed to indirect sunlight. Still further, the invention intends the 
formation of "shadows" and the like in a camouflage pattern such as in 
areas of the pattern not previously colored or not previously bearing 
indicia, the shadowing being formed as representational of the manner in 
which shadows are formed in nature. The invention therefore intends an 
improvement in camouflaging effect for articles provided with a camouflage 
pattern produced according to the invention. 
SUMMARY OF THE INVENTION 
The invention provides methods for increasing a camouflaging effect in a 
camouflaging pattern as well as articles produced according to the methods 
of the invention. In a preferred method of the invention, a photochromic 
material is coated over at least portions of a camouflaging pattern, the 
photochromic material being capable of different chromic states at 
different ambient light levels. In particular, a preferred photochromic 
material so employed exhibits a colorless chromic state when subjected to 
ambient light levels such as are encountered in indoor environmental 
situations or outdoors such as when direct sunlight is absent or obscured 
by shading structures and the like. The preferred photochromic materials, 
when exposed to direct sunlight or to substantially increased ambient 
light levels, then exhibit a change to a chromic state causing a color 
change in the photochromic material. When the photochromic material is 
disposed over a colored material in the camouflaging pattern, the color of 
the material in the camouflaging pattern can combine with the color of the 
photochromic material in the chromic state so produced to provide an 
additive color function, that is, the colors of the original camouflaging 
pattern and of the photochromic material printed thereover can produce a 
color change of a desirable nature which acts to increase the camouflaging 
effect of the original camouflaging pattern, this increased camouflaging 
effect being particularly suitable to the increased light level conditions 
which are brought about by exposure to direct sunlight, etc. On return of 
ambient light levels to or toward original conditions, the photochromic 
material changes color to the original chromic state which, in the case of 
certain preferred photochromic materials disclosed herein, is to a 
colorless chromic state. Preferred photochromic materials according to the 
invention are therefore seen to be reversible. 
A variety of photochromic materials can be useful according to the 
invention to include light-sensitive and/or heat-sensitive materials 
capable of color changes and particularly reversible color changes, these 
materials including both inorganic and organic materials including 
polymeric materials, microencapsulated materials and paints inter alia. 
Photochromic dyes useful according to the invention can be formulated to 
exist in a "sol" or similar dispersion. Aqueous solutions of photochromic 
materials useful according to the invention can also be formulated. 
Photochromic materials useful according to the invention can exhibit color 
changes from colorless to colored states, from "lighter" colors and shades 
to "darker" colors and shades or from "darker" colors and shades to 
"lighter" colors and shades. It is to be understood that this variety of 
material choice is referred to herein through the use of the single term 
"photochromic materials" even though particular photochromic materials are 
explicitly disclosed herein in descriptions of the preferred embodiments 
of the invention. 
According to the invention, photochromic materials are coated over 
particular portions of an existing camouflage pattern and particularly 
along edges of structure within the pattern such as, in a representation 
of vegetative matter in a pattern, the edges of representations of leaves, 
stems, branches, stalks, trunks, vegetative masses and borders 
therebetween which are representative of structure within the existing 
pattern. In an existing camouflage pattern which is improved according to 
the invention, at least certain representational portions of the 
camouflaging pattern can be formed of conventional inks or similar 
materials which are incapable of color change. Those portions of the 
existing camouflaging pattern which are coated with particular 
photochromic dye-containing ink as described herein either do not exhibit 
a color change or only a relatively minor color change at ambient light 
levels such as exist indoors during daylight hours or which exist outdoors 
such as during periods when the sun is behind clouds or blocked by natural 
or man-made shading structure. However, exposure to the sun or the like of 
the camouflaging pattern having photochromic overcoating causes the 
photochromic overcoating to substantially change color or hue, the color 
of the photochromic material causing a color change in at least a portion 
of the pattern which was previously colored or causing a color change in 
at least a portion of the pattern which was not colored or colored only as 
background. The newly colored area, which can take a representational 
shape such as a shadow or the like, produces a colored area in the 
camouflaging pattern which is more effectively camouflaging under 
conditions of increased light levels such as direct sunlight. An existing 
camouflaging pattern per se is possibly capable of producing a perceived 
increase in brightness or reflective intensity on exposure to ambient 
lighting levels of greater intensity such as direct sunlight. However, the 
existing camouflaging pattern per se will only exhibit a nominally 
increased reflectivity and does not change color to a color or hue capable 
of providing an increased camouflaging effect for a given light level. 
When utilizing photochromic materials which are colored at different 
chromic states, the photochromic material can be used to form particular 
portions of a camouflaging pattern either with or without overcoating 
portions of an existing camouflaging pattern. In such a situation, the 
photochromic material is conveniently employed not only at the edges of 
representations of vegetative structure in the pattern but also in the 
bodies thereof to form entire representations of structure such as entire 
leaves, stems, branches, stalks, trunks and other vegetative masses as 
well as shadows of such structure. Similarly, photochromic materials can 
be coated over or can form at least some or all of a camouflaging pattern 
including major portions of at least certain structure including 
representations of leaves, stems, stalks, branches, trunks, vegetative 
masses and borders therebetween as well as shadows of such structures. 
Photochromic materials of differing chromic states can be coated over or 
form at least some or all of representational structure forming a 
camouflaging pattern including representation of leaves inter alia. 
Accordingly, the invention provides camouflaging patterns and methods for 
forming such patterns wherein colors within the pattern change on exposure 
to sunlight or ambient lighting levels of increased intensity, the color 
change being similar to the color change of environmental background 
colors including formation of shadows when exposed to lighting of 
increased intensity such as direct sunlight. 
It is another object of the invention to provide methods and articles so 
produced for increasing the camouflaging effect of any camouflaging 
pattern through the formation of at least portions of the camouflaging 
pattern from a photochromic material or from overprinting of a 
photochromic material onto existing portions of a camouflaging pattern to 
increase the camouflaging effect of the pattern, thereby increasing the 
versatility and effectiveness of the camouflaging pattern. 
It is a further object of the invention to provide methods for increasing a 
camouflaging effect and articles so produced of a camouflaging pattern by 
changing the chromic state of materials forming at least some or all of 
the camouflaging pattern on exposure to changing ambient lighting 
conditions. 
Further objects and advantages of the invention will become more readily 
apparent in light of the following detailed description of the preferred 
embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings and particularly to FIG. 1, a portion of an 
original camouflaging pattern is seen at 10 to comprise a representation 
of a branch 12, a representation of a leaf 14, a representation of a trunk 
16 of a tree and representations of veins 18 of the leaf 14. A 
camouflaging pattern such as the portion of such a pattern seen at 10 
utilizes a variety of shapes and colors to produce a concealing function. 
Colors employed for various areas of the pattern 10 include tans, blacks, 
white, browns, golds, greens and grays inter alia. Differing areas of the 
pattern 10 are differently colored in order to produce a camouflaging 
effect. Representations of structure such as the representation of the 
branch 12 can be seen to have various areas thereof colored differently. 
In the example of the branch 12, two different areas of said branch 12 are 
colored gray as indicated by the numeral 17 while the remaining portion of 
the branch 12 is colored brown as indicated by the numeral 15. For 
camouflaging effect, and to provide an impression of coloring in nature, a 
representation of structure such as the branch 12 is typically colored 
more than one color. Although the areas of differing color as seen in FIG. 
1 are seen to be separated by black lines due to the fact that FIG. 1 is a 
line drawing, in actual practice some areas of the pattern 10 would not 
have a black line disposed therebetween. In such situations, one color 
would simply end and the other color begin. Still further, a camouflaging 
pattern such as the pattern 10 would have in certain other areas a 
blending of the colors together such as where one color fades into an 
adjacent area of different color. 
The pattern 10 has been simplified as to number of colors and as to the 
size of areas of differing color as well as the number of differing 
colored areas in close proximity to each other. For an example, "wisps" of 
the color gray shown as 17 can be placed in the pattern 10 within larger 
areas of color such as the large areas which are colored with brown as 
seen at 15. The "wisps" of lighter color serve to break up areas of darker 
colors, in particular, and provide a more natural camouflaging effect. It 
is also seen in the pattern 10 that the color black as seen at 11 can be 
used to form relatively large areas of color as well as to provide 
relatively narrow lines between areas of different color. It should also 
be understood that lines between areas of different color can also be 
provided by other colors such as brown as an example of a darker color and 
gray as an example of a lighter color. The color green seen at 13 is 
typically provided within a pattern as coloring a relatively large area. 
The colors green 13, brown 15, gray 17, and tan 19 can further be 
appreciated to have a wide variety of hues or shades within the same 
pattern 10. As might be appreciated from a consideration of the pattern 
10, camouflaging patterns can be infinitely diverse in shape and color. 
According to the present invention, these camouflaging patterns of 
infinite diversity can be improved according to the present invention as 
will be described herein. 
It is known in the art that a camouflaging pattern such as the pattern 10 
is advantageously formed by the successive printing, such as by screening, 
of the different colors onto a substrate which is typically a woven or 
non-woven textile fabric although virtually any surface can receive a 
printed camouflaging pattern onto its surface. According to the present 
invention, at least portions of the pattern 10 of FIG. 1 are coated such 
as by overprinting with photochromic materials which, when exposed to 
ambient light of sufficient intensity such as direct sunlight, changes 
color to produce a different color which is intended to be representative 
of the coloring effect produced in nature and which occurs during a 
substantial change in ambient lighting conditions. Such a color change can 
result from a combining of the "new" color of the photochromic material 
within the color present in the original camouflaging pattern 10 or can 
result from the change of the photochromic material from one state to a 
second state including from a colorless state to a colored state. Changes 
in ambient lighting conditions in nature often occur such as when the sun 
moves from behind a cloud and exposes objects to direct sunlight as 
opposed to a lower level of ambient light existing when the sun is behind 
clouds or other shading structure. The colors of the original camouflaging 
pattern 10 do not change color when exposed to direct sunlight and the 
colors, shades and hues which can be seen in the pattern 10 can only 
become slightly brighter since the reflective capacity and capability of a 
given colored area of the pattern 10 does not change due to an increased 
illumination level. However, placement of a photochromic material over 
some or all or even portions of some or all of the areas of the pattern 10 
marked as being gray by the numeral 17, for example, results according to 
the invention in a change in color of those areas so coated on exposure to 
substantially increased illumination levels such as exposure to direct 
sunlight. In the instance where the photochromic material is colorless at 
low illumination levels, the gray 16 in the pattern 10 is colored solely 
due to the contribution of the ink forming the original pattern 10. On 
exposure to direct sunlight, for example, the overcoated photochromic 
material changes chromic state and becomes a color characteristic of the 
particular photochromic material. The color then perceived for the 
overcoated area is, in general, the additive contribution of the color of 
the area, such as a gray area 17, with the color of the photochromic 
material when exposed to sunlight. The pattern 10 would then exhibit a 
different pattern of color due to the change thus effected. 
Photochromic materials having a colorless state when exposed to low light 
conditions can be coated either over colored portions of a normal pattern 
10 or over uncolored portions of the pattern 10. Exposure to sunlight or 
the like can then cause a representation of structure of a representation 
of the existence of structure, such as a shadow, to form in the enhanced 
pattern. Such a shadow can be caused to "form" over uncoated or coated 
portions of a normal pattern such as the pattern 10 or both. 
While photochromic materials of widely varying color can be applied to a 
camouflaging pattern such as the pattern 10 to produce color changes of 
differing kind and degree, reference is now made to FIGS. 2 through 4 in 
order to more clearly illustrate the effect of the application of a 
typical photochromic material useful according to the invention to a 
localized portion of a camouflaging pattern such as the pattern 10. FIGS. 
2 and 3 represent a particular portion of a camouflaging pattern taken 
from the pattern 10, that portion being identical in FIGS. 2 and 3. The 
localized pattern of FIGS. 2 and 3, as well as FIG. 4, comprises an area 
of a black color as seen at 11, an area of a gray color as seen at 17, and 
an area of a brown color as seen at 15. Shown in "exploded" relation to 
the gray area 17 and the brown area 15 are identically shaped layers 20 
and 22 which are shaped respectively to fit over the gray area 17 and the 
brown area 15, the representation of FIGS. 2 and 3 being idealized in the 
showing of a very thin layer of coating material, that is, the layers 20 
and 22 of photochromic dyestuff, as it would "ideally" exist in spaced 
relation to the portions of the pattern 10. 
As seen in FIG. 2, relatively low ambient lighting conditions prevail due 
to the fact that the sun is illustrated as being blocked out by clouds 24. 
Under these relatively low ambient lighting conditions, the layers 20 and 
22 of "red" dye are colorless. The portion of the pattern 10 seen in FIG. 
2 would therefore appear to be the same color as in FIG. 1 since no color 
contribution is provided by the layers 20 and 22. Note, however, in FIG. 
3, that the emergence of sun 26 to expose the pattern 10 to direct 
sunlight causes the layers 20 and 22 to become red as is indicated by the 
vertical hatching on the layers 20 and 22. Of course, the layers 20 and 22 
are perceived as being red only in the idealized situation where the 
layers 20 and 22 are spaced from the pattern 10 or in the more realistic 
situation where the photochromic red dye comprising the layers 20 and 22 
had been placed on a "white" substrate such that the only color 
contribution would be from the layer 20 and 22. With further reference to 
FIG. 4, however, it is seen that exposure to the sun 26 causes that area 
previously seen as gray at 17 to change color and become a yellow/gold 
color due to the additive contribution of the original gray color 17 and 
the red color from the layer 20 of photochromic material. Similarly, the 
area of the pattern 10 seen in FIGS. 2 and 3 as being brown at 15 is now 
seen in FIG. 4 to be a dark gold due to the additive color contributions 
of the brown color from the original camouflaging pattern 10 and the red 
color from the layer 22 of the photochromic material. 
While the representations provided in FIGS. 2 through 4 are greatly 
simplified and pertain particularly to photochromic materials which are 
colorless under relatively low ambient lighting levels and colored only on 
exposure to relatively higher ambient lighting levels such as direct 
sunlight, it is to be seen that even for such particular photochromic 
materials, literally infinite combinations exist for color change in an 
original camouflaging pattern such as the pattern 10 when some or all of 
the pattern 10 is overcoated with photochromic materials. Given the 
teachings of the invention, it is even possible for the designer of 
camouflaging patterns to design the original pattern itself around the 
various photochromic materials suitable to practice of the invention in 
order that the photochromic materials are used to best advantage. In a 
usual practice of the invention, photochromic materials are preferably 
placed in lighter areas of the pattern 10 which not only allow for greater 
color change but which also provide more definition to the lighter areas 
in the pattern 10 which mimics nature due to increased definition of 
structure in nature when exposed to direct sunlight or the like. Using 
photochromic dyestuffs in ink formulations such as will be described 
hereinafter, it is generally advantageous to change greens and browns in 
original patterns to yellows and oranges in the patterns improved 
according to the invention. Dyestuffs which turn red from a colorless 
original form will change relatively large light areas such as gray areas 
or "white" areas to a red color on exposure to sunlight. The browns in a 
camouflaging pattern are usually of differing intensity and range between 
lighter milk chocolates to darker milk chocolates. A red dyestuff on a 
darker milk chocolate base will result on exposure to sunlight in a dark 
gold color while a red dyestuff on a lighter milk chocolate will produce a 
yellow gold color. Combinations of coloring can also be provided which 
will cause certain camouflaging patterns to be more useful in the spring 
of the year while other camouflaging patterns will find greater utility in 
the fall of the year. 
Photochromic materials vary in the nature of the color change exhibited 
when exposed to sunlight or the like. Certain photochromic materials 
including certain materials preferred at present due to ability to rapidly 
change color, etc., typically cause a camouflaging pattern to change from 
relatively lighter colors to relatively darker colors. In such situations, 
gray areas of a pattern as well as white to off-white areas are typically 
more favorably coated with photochromic material since darker areas in an 
original pattern will typically only darken. Photochromic materials 
capable of changing from darker colors to lighter colors of the same color 
would be advantageously utilized according to the showing of FIGS. 5A and 
5B. In FIG. 5A, a leaf 28 is seen to be formed of a dark green color in 
the body of the leaf 28, the leaf further having dark brown veins 30. FIG. 
5A illustrates relatively low ambient lighting conditions. Under increased 
ambient lighting conditions such as exposure to direct sunlight as 
represented by FIG. 5B, portions of the dark green areas of the leaf 28 
change to a lighter green whereas edges of the leaf 28 as seen at 32 
become a yellow color. The veins 30 change from a dark brown to a lighter 
brown. Color changes as can be appreciated from a comparison of FIG. 5A 
with FIG. 5B illustrate color changes found in nature such as when the sun 
moves out from behind a cloud, it being the intent of the invention to 
produce similar color changes which are as natural as possible in order to 
provide an increased camouflaging effect. 
When photochromic materials suitable to particular camouflaging 
opportunities are not readily available or are too expensive for 
commercial consideration, the invention envisions the use of fractional 
tones such as illustrated simply in FIG. 6 to provide desired camouflaging 
effects. In FIG. 6, a greatly enlarged portion of structure found in a 
camouflaging pattern is conveniently taken to be a portion of a leaf or 
the like wherein major portions seen at 34 of a leaf or the like are 
caused to be "full tone" which could conveniently be a relatively dark 
green color such as might be representative of a leaf or other vegetation. 
A multiplicity of small white dots 36 are caused to be formed throughout 
the portions 34, these dots 36 being printed as half tones, quarter tones 
or other fractional tones with photochromic material in order to provide 
an ovcerall lighter color on exposure to sunlight. The coloration of the 
fractionally toned pattern seen in FIG. 6 thus moves from a darker color 
under ambient lighting conditions of a relatively low level to a lighter 
color on exposure to direct sunlight or substantially higher ambient 
lighting conditions. As one example, the dots 36 can be essentially light 
or of a gray color such as the gray 17 in the pattern 10. Overcoating of 
the "gray" dots 36 with a suitable photochromic dye material causes the 
gray dots 36 to become gold on exposure to sunlight, thereby improving and 
increasing the camouflaging effect of the pattern. 
Particular photochromic materials which are presently known to be 
advantageously utilized in the practice of the invention include 
aryl-substituted heterocyclic photochromic dyestuffs such as are produced 
under the trade name Reverasacol and made available by the Keystone 
Aniline Corporation of Chicago, Ill. The Reverasacol materials take the 
form of dry dye powders which are converted to ink formulations by 
companies such as Flexible Products, Inc. of Marietta, Ga., and Color 
Technologies, Inc., of Watkinsville, Ga. These photochromic dyes are 
substantially colorless under relatively low ambient lighting conditions 
but change variously to blues, greens, reds, oranges, purples and yellows 
when exposed to sunlight or other high ambient lighting conditions. The 
Reverasacol dyes are soluble in polymers and various solvents and can be 
used in differing percentages to form color combinations in both resin and 
binder formulations. Formulations can be provided for adherence to 
substrates formed of essentially any material. Combination of these 
photochromic dyes with ordinary dyes and/or pigments is also possible and 
within the scope of the invention. 
The dyestuffs referred to above can be formulated as inks in aqueous, that 
is latex, based formulations and in oil formulations to produce inks 
applicable by ordinary silk-screening methods and similar known 
methodology. Clear plastisol printing inks, such as available from the 3-G 
Corporation, Morristown, Tenn., are available for mixing with dyestuffs. 
Certain of the plastisol inks allow addition of the dyestuffs under normal 
agitation with percentages of the dyestuffs as a part of the total 
formulation typically ranging from 0.1% to 2%. Concentrations of PBC 
printing inks into which the dyestuffs can be incorporated allow 
modification of hardness and flexibility of the resulting ink by additions 
of plasticizers such as DINP. Latex printing inks incorporating the 
present dyestuffs can also be provided by flat screen printing, rotary 
screen printing, roller printing and ink jet printing inter alia. In latex 
formulations, the dyes are predispersed into an aqueous solution typically 
comprising 70% water, 25% dyestuff, 1% surfactant such as Synthropol KB 
manufactured by ICI Chemicals and 4% thickener such as ASE-60 manufactured 
by Rhome and Hauss Chemical along with sufficient ammonia to neutralize 
pH. The dye solution thus formed is mixed to make a ready to use ink with 
a binder such as Orco Pad Binder HLF, from Orco Dyestuffs Corp. and a 
thickener such as Orco Clear Conc. 331, from Orco Dyestuffs Corporation. A 
typical solution includes 20% binder, 75% thickener and 5% of the dye 
solution formulated above. 
A coating suitable for plastic and metals is formulated using 35% of an 
acrylic resin such as B-66 from Rhom & Haas, 8.75% toluene, 42.2% xylene, 
from 12 to 14% PM acetate and 0.1 to 2% of the dyestuff formulation. While 
these particular formulations are very useful, it is to be understood that 
other formulations of photochromic materials including the dyestuffs 
particularly disclosed above are useful in the practice of the invention. 
Referring now to FIGS. 7 and 8, a portion of a camouflage pattern is seen 
to comprise a representation 40 of a tree trunk or the like under 
relatively low ambient light conditions such as would exist when the sun 
is obscured by a cloud or the like. As seen in FIG. 7, the representation 
40 of the tree trunk does not cast a shadow or casts only a very faint 
shadow (not seen in the drawing). However, when the sun seen at 44 in FIG. 
8 is no longer obscured by a cloud or other obscuring structure, it is 
seen in the pattern of FIG. 8 that a representation 42 of a shadow is 
formed. The representation 42 of the shadow forms by virtue of having 
previously coated an area of the camouflage pattern with a clear and 
colorless photochromic material which, on exposure to direct sunlight or 
the like as described herein, causes an area of the camouflage pattern to 
change color to a gray, brown or other darker color to mimic the formation 
of a shadow as occurs in nature. The photochromic material which causes 
formation of the representation 42 of the shadow can be overcoated onto 
any portion of the camouflage pattern including areas of the pattern 
previously coated with ink materials or portions of the pattern not 
previously coated with ink materials or both. It should also be understood 
that the camouflage pattern represented in FIGS. 7 and 8 would likely have 
a number of different shadow representations which would form on exposure 
to sunlight or the like. It is also apparent that the formation of shadows 
as described in combination with other increased camouflaging effects as 
described herein can all take place on the same camouflage pattern in 
order to increase the camouflaging effect of the pattern when exposed to 
direct sunlight or the like. 
Photochromic materials solvated by organic solvents or by water-based 
solvents including water per se are commonly available. Examples of such 
materials which change from a clear, colorless state to virtually any 
visible color are referred to in U.S. Pat. No. 5,730,961, the disclosure 
of which is incorporated hereinto by reference. Photochromic materials 
described in U.S. Pat. No. 5,730,961 include spiropyrans and spiroxazines. 
A wide variety of suitable photochromic materials are available and include 
those photochromic materials described in the following U.S. Pat. Nos.: 
______________________________________ 
5,176,905 
5,591,255 
5,435,994 
5,630,869 
5,446,150 
5,708,181 
5,456,905 
5,728,758 
______________________________________ 
The disclosures of the patents thus listed are incorporated hereinto by 
reference. 
Suitable photochromic materials compounded in suitable solvents for 
printing as particularly intended according to the invention can be 
obtained from sources such as GSR Enterprises, 561 Buckeye Court, Santa 
Rosa, Calif. 95409; and from 2.sub.nd Story Concepts, 975 Higbee Avenue, 
N.W., Canton, Oh. 44718. Aqueous-based materials particularly suited for 
printing on fabrics can be obtained from 2.sub.nd Story Concepts 
particularly as materials which change from clear to yellow, blue, red or 
gray and which can be compounded by mixing to provide virtually any color 
of the spectrum. 
The invention also encompasses the addition of materials known as puffing 
agents to the photochromic inks used to form at least a portion of a 
camouflaging pattern. Such puffing agents typically take the form of fine 
particles of resinous materials such as polystyrene and the like, such 
materials and processes for use of such materials being disclosed in U.S. 
Pat. Nos. 4,933,991; 5,133,088 and 5,653,166, the disclosures of which 
patents are incorporated hereinto by reference. According to the 
invention, the puffing agents could be added to both photochromic inks and 
conventional inks, if both kinds of inks are present in a pattern, 
although the puffing agent would not necessarily be present in all 
portions of the pattern. A puffing agent could potentially be added only 
to a portion of a given color, either photochromic or conventional, when 
such color portions are contiguous in order to provide shadowing or other 
effects. 
Processing according to the invention when using puffing agents includes 
typical heating steps and the like which can essentially be that 
methodology disclosed in the patents referred to above, photochromic inks 
useful according to the invention as described hereinabove having thermal 
stability characteristics similar to those of conventional inks used in 
forming camouflage patterns, these thermal stability characteristics 
allowing ready use of puffing agents. It is further to be understood that 
puffing agents can be used as taught herein in camouflage patterns printed 
solely with conventional, non-photochromic inks. 
The invention further encompasses the concepts of inclusion of holograms 
and the like in a camouflage pattern, such holograms being produced 
according to U.S. Pat. Nos. 3,808,024 and 4,838,965, the disclosures of 
which arc incorporated hereinto by reference, and by other techniques 
known in the industry. Essentially, the invention extends to the use of 
either or both photochromic inks and conventional inks in the formation of 
a hologram, the hologram then being preferably used in a camouflage 
pattern. However, it is to be understood that a hologram pattern formed in 
part or wholly with photochromic inks could be utilized for the formation 
of printed patterns other than camouflage patterns. It is further to be 
seen that puffing agents can be used in those inks utilized to form 
holograms for inclusion in camouflage patterns or the like according to 
the invention. Processing steps necessary to formation of such holograms 
and application thereof to fabrics and the like are described in the 
aforesaid patents since these techniques are useful with photochromic inks 
in a manner similar to use of conventional inks due to heat stability and 
other characteristics of the photochromic inks which are similar to 
corresponding characteristics of conventional inks used for formation of 
holograms used to form patterns on fabrics and the like. 
While the invention has been particularly described in reference to the 
formation of camouflaging patterns on textile fabrics and the like, it is 
to be understood that the camouflaging patterns of the invention can be 
directly formed onto a variety of substrates in addition to fabrics 
utilized for formation of clothing and the like. Examples include direct 
formation of the camouflaging patterns onto weaponry, optical equipment, 
vehicles, buildings including hunting blinds and the like, aircraft, 
watercraft, as well as small accessories including knives, bottles, and 
communication equipment inter alia. Photochromic materials other than 
chromasome ink based materials in differing base compositions and 
providing a variety of color change options find utility according to the 
invention. While light sensitive dyes find particular utility according to 
the invention, it is to be understood that liquid crystalline material and 
other photochromic materials find utility according to the invention. 
Accordingly, it is believed to be apparent that the invention is to be 
interpreted in light of the following recitation of the invention as 
provided in the appended claims.