Confidential information bearing article

A confidential information bearing article comprising a cover sheet adhered to a base sheet is provided which is capable of providing hidden confidential information to a recipient. Through the use of camouflage, obscuring, and opacifying and reflectivity increasing coatings, the paper used for the mailer becomes effectively opaque, and information printed on the inside of the article is substantially unreadable from the outside. The article includes an adhesive for securing the base sheet and cover sheet and perforations along the edges to assist the recipient in opening the article.

BACKGROUND OF THE INVENTION 
This invention relates to a confidential information bearing article, and 
more particularly to a construction in which a base sheet and a cover 
sheet having an opacifying and light reflective coating on their outer 
surfaces and bearing confidential information on their inner surfaces are 
secured together so as to prevent reading of the confidential information 
until opened. 
A variety of articles have been used to conceal secret or confidential 
information within a two or more ply construction and to prevent 
unauthorized viewing thereof. Such confidentiality has been needed for 
lottery tickets, promotional coupons or offers, game cards, pay checks and 
the like. Typically, the confidential information is sealed between two or 
more plies of paper, paper board, plastic or the like. The construction is 
designed to be pulled apart to reveal the confidential information. 
Likewise, many other types of confidential information are transmitted 
through the mail in the form of checks, invoices, bank statements, and the 
like. Envelopes have been typically used for transmitting this type of 
confidential information. Postcards provide an inexpensive alternative to 
sending messages in envelopes, but in the past they have not been suitable 
for the delivery of confidential information because the information is 
not concealed. 
However, attempts have been made to produce post card constructions which 
permit the obscuring of confidential information until receipt by the 
addressee. For example, Tanaka, U.S. Pat. No. 4,278,199, teaches a post 
card construction in which confidential information is preprinted on the 
card, and then an opaque cover member which is substantially smaller in 
size than the card is adhered to the card, covering the confidential 
information. 
Shishido, U.S. Pat. No. 4,742,954, also teaches a post card construction in 
which preprinted confidential information may be hidden from view by a 
laminated cover sheet which is secured to a transparent protection film 
layer bonded to a base sheet. The cover sheet is delaminated from the base 
sheet by the addressee of the post card to reveal the confidential 
information. 
However, the construction of Shishido comprises several layers, one of 
which must be laminated by a heating operation requiring a closely 
controlled temperature range. Shishido also requires at least two separate 
printing operations. Further, neither Shishido nor Tanaka describe a 
procedure for automating the production of a series of postal cards. 
Ormond, U.S. Pat. No. 3,329,333 also teaches a post card or mailer device 
for checks or other confidential information which consists of a base 
sheet containing indicia, a cover sheet having a tacky adhesive around its 
periphery, and a removable intermediate sheet which is attached to the 
tacky undersurface of the cover sheet. The intermediate sheet is removed 
before mailing and the cover sheet is adhered to the base sheet and 
remains secure until the cover sheet is removed to reveal the intended 
message. In an alternative embodiment, the cover sheet is applied directly 
to the base sheet with a pressure sensitive tape for use in automated 
mailings. 
Hieken, U.S. Pat. No. 3,126,211, relates to a mailer for checks, invoices, 
and other confidential information consisting of a base sheet bearing 
confidential indicia and addressee information and a cover sheet which is 
strippably secured to the base sheet to cover the confidential 
information. 
Chang, U.S. Pat. No. 4,425,386, relates to a multi-sheet business form 
having four plies. The top ply has on its surface a spot coating which 
comprises chromogen-containing pressure rupturable microcapsules and a 
color developer material which upon impact ruptures and forms an image on 
the underlying plies. The second and third plies may also support the 
coating on all or portions of their surfaces, while the fourth ply serves 
as a backing sheet. This form may also be printed in a continuous form 
assembly. 
Welsch et al, U.S. Pat. No. 4,172,605 discusses the use of a chemically 
reactive printer ribbon in which the ribbon is coated with a color forming 
chromogenic substance in solution. Selected areas on the front of a 
business form are coated with a color developer material so that when 
impacted with the ribbon, an image is formed on the paper. However, the 
ribbon must be in direct contact with the underlying receiving sheet to 
permit transfer of the color former to the color developer for proper 
image formation. 
A problem with previous post card or envelope mailers containing 
confidential information has been the lack of opacity of the paper stock 
used. When held up to a strong light source, the confidential information 
could be perceived through the cover and/or base sheets of the 
construction. Increasing the thickness of the paper stock used results in 
greater opacity, but adds material costs to the mailer construction and 
makes the mailer more difficult to process as a continuous form. Further, 
the added thickness and weight of the mailer may increase postal costs. 
Other commercially-available mailers incorporate a random ink pattern on 
the inner surfaces of the top and bottom sheets which attempt to prevent 
the contents of the mailer from being readable through the mailer. See 
also U.S. Pat. Nos. 3,988,971, 4,081,127, and 4,095,695 which are hereby 
incorporated by reference. Other mailers employ a random block out pattern 
on the inner surfaces of the mailer having specific areas which have been 
coated with carbon ink. These carbon patches correspond with areas on the 
outer surface of the cover sheet which have been printed with block out 
patterns so that confidential information may be printed on the outside of 
the mailer and be transferred to an insert sheet inside of the mailer 
without being read from the outside. This mailer also includes a tab 
portion which is releasably secured to one ply of the mailer for opening. 
See U.S. Pat. No. 4,157,759. However, all of these mailers require the 
insertion of a separate sheet containing the intended message. 
In addition to the limitations of the prior art, the use of sophisticated 
processing equipment by the U.S. Postal Service has resulted in new 
restrictions on the types of paper that may be used for mailers. For 
example, envelopes or mailers made from coated paper or plastic cannot be 
properly processed when using automated equipment. Also, paper containing 
dark fibers or which has block out patterns printed on the interior and/or 
exterior surfaces thereof may interfere with the operation of the optical 
character readers (OCRs) and bar code sorters used by the Postal Service. 
As a result, the Postal Service has requested that the address-bearing 
surface of a mailer must have a sufficient light reflective surface so 
that it can be read by an OCR scanner and must have a reflected light 
difference between the paper and the ink of at least 30%. In addition, the 
paper used to construct the mailers should have sufficient opacity to 
prevent printing, such as block out patterns, from inside the mailer from 
showing through in the OCR and bar code reading areas so that such 
printing does not interfere with OCR scanning. 
Banking institutions have also implemented new regulations in regard to 
checks. In May, 1988, the Federal Reserve Board issued Regulation CC to 
implement the Expedited Funds Availability Act to facilitate the expedited 
processing of checks. Many checks are printed with markings on the reverse 
side of the check, such as carbon bands, blocks of jumbled letters and/or 
numbers, random or designed backgrounds, or cross-hatching applied for 
security in mailers to prevent reading the check information from the 
reverse side or through the mailer. However, when endorsing checks of this 
nature, depositary banks may be unable to avoid the markings, patterns, or 
designs, and consequently, paying banks may not be able to read the 
endorsement, causing the check to be returned and resulting in an unwanted 
delay in payment processing. Consequently, the American National Standards 
Institute (ANSI) which issues standard specifications for check 
endorsements has recommended that the check background color should be 
plain white, or a plain, light pastel color, and if printed patterns or 
designs are used as background, they should be in a muted, light color. 
Accordingly, the need still exists in the art for a simple construction for 
concealing a wide variety of confidential information such as lottery 
tickets, game cards, coupons, checks, financial instruments, and other 
documents containing confidential information. The construction should be 
capable of keeping the printed information confidential until opened by 
the recipient or addressee and, in the case of mailer constructions, which 
complies with the recommended standards set by the U.S. Postal Service and 
banking institutions. Further, there remains a need for such a 
construction which can be used in an automated system for the production 
of a series of such confidential information bearing articles. 
SUMMARY OF THE INVENTION 
The present invention meets that need by providing a confidential 
information bearing article such as a mailer construction for checks and 
other confidential documents comprising a cover sheet adhered to a base 
sheet which may be easily printed by automated systems and insures 
confidentiality until receipt by the addressee through the use of 
information obscuring coatings applied to the outer and/or inner surfaces 
of the cover and base sheets. An adhesive, applied to the edges of the 
article, enables the recipient to readily peel back the cover sheet and 
read the confidential information. 
In accordance with one aspect of the present invention, a construction 
information bearing article is provided which comprises a base sheet, a 
cover sheet overlying the base sheet and an adhesive securing the cover 
sheet and base sheet such that the cover sheet and base sheet are readily 
separable. By "readily separable" we mean an adhesive which will maintain 
the integrity of the construction during normal handling but which will 
permit separation of the plies and access to the interior of the 
construction by the application of force by the end user. However, it is 
desired that the adhesive be of sufficient strength to leave evidence of 
the fact that a user has gained access to the interior of the 
construction. The cover sheet and base sheet may contain printed 
information on one or more of their respective inner surfaces. 
To help insure that the information printed on the base sheet and cover 
sheet remains hidden from view, the material comprising the base sheet and 
cover sheet should have a high level of opacity combined with images 
confusing to the eye, thus rendering the printed matter inside 
substantially unreadable through the mailer construction. To achieve this, 
the respective outer surfaces of the base sheet and cover sheet are 
printed with a camouflaging block out pattern. In a preferred embodiment, 
the camouflage pattern comprises a random printed pattern of jumbled 
numbers and jumbled letters printed with a camouflage ink. The camouflage 
pattern is first overcoated with an obscuring coating of a colored ink, 
and then overcoated with means for increasing the opacity and reflectivity 
of respective outer surfaces of the base and cover sheets such as an 
opacifying and reflectivity increasing coating. This results in a light 
reflective surface on the outside of the mailer which helps prevent 
printed matter on the inside from being read. Optionally, the same series 
of steps may be performed on the inner surface of the construction. 
The confidential information bearing article includes an adhesive which, in 
one embodiment of the invention, is applied around the peripheral edges of 
the cover sheet and base sheet. The cover sheet and base sheet also may 
have perforated removable edge portions for easy separation. 
In a preferred form, the article comprises a mailer construction in which 
the cover sheet includes a die cut window area which corresponds to the 
portion of the base sheet in which addressee information is to be printed. 
The window area of the cover sheet is preferably covered with a 
transparent material such as glassine on its inner surface to provide 
protection to the addressee information. 
In another embodiment of the invention, a confidential information bearing 
article is provided which comprises a single sheet having a first half 
portion and a second half portion, wherein the first half portion may be 
folded over onto the second half portion to form a folded sheet. The inner 
surface of the sheet may be printed with indicia. The surfaces of the 
sheet which will form the outer surfaces of the mailer construction are 
printed with the camouflaging block out pattern and coated with obscuring 
and opacifying and reflectivity increasing coatings as described above. 
The article includes an adhesive which may be applied around the 
peripheral edges of the first half portion and second half portion of the 
sheet, and may include perforated removable edge portions. In a preferred 
form, the invention comprises a mailer construction which also may include 
a die cut window covered with a transparent material such as glassine on 
the first half portion of the sheet. 
In another embodiment of the invention, a confidential information bearing 
article is provided which comprises a single sheet continuous form having 
a left half portion and a right half portion. The front surface of the 
continuous form, which forms the inner surfaces of the article may be 
printed with indicia with the use of automated equipment. The back surface 
of the continuous form, which forms the outer surface of the article, is 
printed with the camouflaging block out pattern and coated with the 
obscuring coating, then overcoated with the opacifying and reflectivity 
increasing coatings as described above. After the form has been printed 
and coated, the left half portion of the form may be folded onto the right 
half portion of the form to form a continuous folded sheet. The article 
also includes transverse perforations for separating the form into 
individual articles and an adhesive which may be applied around those 
areas which form the peripheral edges of the individual articles, and may 
also include perforated removable edge portions for easy separation. In a 
preferred form, the article comprises a continuous mailer form which also 
includes die cut windows covered with a transparent material such as 
glassine or the like at predetermined intervals along the left half 
portion of the form. 
In yet another embodiment of the invention, a confidential information 
bearing article is provided which comprises a base sheet, a cover sheet 
overlying the base sheet, and an indicia-bearing sheet positioned between 
the base and cover sheets. The respective inner surfaces of the cover and 
base sheets may be printed with indicia as well. The respective outer 
surfaces of the article are printed with the camouflaging block out 
pattern and coated with the obscuring and opacifying and reflectivity 
increasing coatings as described previously. Again, the cover and base 
sheets are preferably secured at their peripheral edges with an adhesive 
and have perforated removable edge portions. In a preferred form, the 
article comprises a mailer which may also include a die cut window on the 
cover sheet which is covered with a transparent material such as glassine. 
In a further embodiment of the invention, a confidential information 
bearing article is provided which comprises a base sheet and a cover sheet 
overlying the base sheet. The respective inner surfaces of the base sheet 
and cover sheet are printed with the camouflage block out pattern and 
coated with the obscuring and opacifying and reflectivity increasing 
coatings as described above. The inner surfaces of the base sheet and 
cover sheet are then overprinted with indicia. Thus, the reflective 
coating is on the inside of the article and the outside of the article has 
a clean, uncoated surface. The cover and base sheets are preferably 
secured at their peripheral edges with an adhesive as described above and 
include perforated removable edge portions. In a preferred form, the 
article is a mailer which also preferably includes a die cut window on the 
cover sheet covered with a transparent material such as glassine or the 
like. 
Accordingly, it is an object of the present invention to provide a 
confidential information bearing article including a base sheet and a 
cover sheet bearing confidential information secured within which is 
simPle to manufacture and print by automated systems and which is capable 
of providing hidden confidential information to a recipient. Other objects 
and advantages of the invention will be apparent from the following 
description, the accompanying drawings and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
For ease of understanding, the confidential information bearing article of 
the present invention will be described with reference to a preferred 
mailer construction. However, it will be apparent to those skilled in the 
art that the invention is applicable to a variety of articles such as 
lottery tickets, coupons, promotional game cards, pay checks, and the like 
where there is a need to maintain information confidential until an 
article is opened by the recipient. 
The preferred mailer construction of the present invention is illustrated 
in FIG. 1 and includes a cover sheet 10 and a base sheet 12. The mailer is 
preferably constructed of a cellulosic material, preferably a 24# bond 
paper, although other weights of paper or paper-like materials are also 
within the scope of the invention. An adhesive 14 is applied to the 
peripheral edges of the mailer to seal its contents but enable the 
recipient to readily peel back the cover sheet and read the information 
contained therein. The adhesive is preferably a hot-melt glue, although 
other known adhesives such as pressure sensitive adhesives may be used. In 
other constructions of the confidential information bearing article of the 
present invention, it may be useful to apply an adhesive, such as a 
fugitive adhesive, over substantially the entire surface of the base 
and/or cover sheets. 
An optional die cut window 16 is positioned over the area where the name 
and address information of the recipient is to be printed on the inner 
surface 22 of the mailer. The window is covered with a transparent 
material such as glassine or the like which is secured around the edges of 
the window to give further protection to the addressee information. 
Perforations 19 are also positioned inside of the peripheral sealed edges 
of the mailer and can be removed by the recipient to assist in opening the 
mailer. 
As illustrated in FIG. 2, the inner surface 20 of cover sheet 10 and the 
inner surface 22 of base sheet 12 may contain confidential printed 
information 23 such as a combined payroll check and stub. To ensure the 
confidentiality of the printed information inside the mailer, the 
respective outer surfaces of the base sheet and cover sheet are printed 
with a camouflage image and then coated with obscuring and opacifying 
coatings. These three means work together to prevent the printed material 
inside from being read, while at the same time presenting an outer surface 
of good reflectivity. 
Referring now to FIGS. 5-6, the information obscuring coating process of 
the present invention is illustrated. The first step in the process 
involves printing the respective outer surfaces of the cover sheet and 
base sheet with a camouflage pattern, C, as illustrated in FIG. 5. A 
preferred camouflage pattern is a block out pattern which includes a 
random printed pattern of jumbled letters and jumbled numbers in which the 
lines of type are overlapping. Preferably, the type fonts and sizes 
approximate the type fonts and sizes which are used to print the 
confidential information contained on the interior faces of the mailer. 
However, other camouflage patterns may be used to good effect. 
The camouflage pattern is preferably printed using a dark gray, rather than 
black, ink. In this manner, the color, pattern, and density of the 
camouflage pattern as perceived by the eye will closely match the color, 
pattern, and density of the confidential information printed within the 
mailer when viewed by transmitted light. The difference is that the 
confidential information is printed on the inner faces of the sealed 
mailer while the camouflage pattern is printed on the outer faces of the 
mailer. Additionally, where the confidential information is printed in a 
color other than black or dark gray, it may be desirable to use a similar 
color to print the camouflage pattern. For example, if the confidential 
information is printed using a blue ink, the camouflage pattern may also 
be printed in blue. 
Next, the camouflage pattern is overcoated with an obscuring coating D, 
such as a gray ink. The gray ink may also contain pigments. However, it is 
preferred to use dye-based inks. Although aqueous-based inks are 
preferred, any ink suitable for printing by flexography, gravure, 
letterpress, wet offset, or dry offset may be used. 
One preferred ink comprises about 5% by weight hydroxyethylated 
polyethylene imine, available from Morton Thiokol; about 8% by weight 
sulfonated nigrosine; about 5% to 15% by weight isopropyl alcohol; about 
0.5% by weight of a defoamer such as SWS 213 Defoamer, available from Air 
Products; and 71% to 85% water by weight. In an alternative formulation, 
the gray ink may comprise about 40% by weight polyethylene glycol 400, 
available from Union Carbide; about 5% by weight of a 50% gluconic acid 
solution; 6% by weight tetrahydrofurfuryl alcohol; about 2% by weight 
Solvent Black 7; about 5% to 10% by weight isopropyl alcohol; about 0.5% 
by weight defoamer; and 35% to 45% water by weight. In another alternative 
formulation, the gray ink may comprise about 15% by weight 
methoxypolyethylene glycol 350, available from Union Carbide; about 5% by 
weight of a 50% gluconic acid solution; about 6% by weight 
tetrahydrofurfuryl alcohol; about 2% by weight Solvent Black 7; about 5% 
to 10% by weight isopropyl alcohol; about 0.5% by weight defoamer; and 
about 60% to 70% water by weight. 
As discussed above, in certain situations it may be desirable to print the 
camouflage image in a color of ink other than gray. Exemplary colored ink 
compositions for use in the practice of the present invention include a 
blue ink comprising about 5% Reactive Blue 72 dye, about 5% to 15% 
isopropyl alcohol, and the remainder water, all percentages by weight. An 
exemplary red ink comprises about 5% Reactive Red 24 dye, about 5% to 15% 
isopropyl alcohol, and the balance water. An exemplary yellow ink 
comprises about 4% Direct Yellow 166 dye, about 10% isopropyl alcohol, and 
the remainder water. 
The exact formulation of the ink making up the obscuring coating is not 
critical. However, it should function to reduce the contrast between the 
dark jumbled characters of the camouflage pattern and the remainder of the 
outer surface of the sheet. By reducing the print contrast ratio between 
pattern and unprinted surface, the camouflage pattern becomes nearly 
impossible to read by the eye when the light reflective opacifying 
overcoat has been applied. Accordingly, automated postal sorting equipment 
including OCR scanners are not able to "read" the camouflage pattern and 
the pattern does not interfere with the automated reading of addressee 
information. 
In the final coating step, the obscuring coating is overcoated with an 
opacifying reflectivity increasing coating, O, such as a white reflective 
ink. Such an ink is CR 37861 Aqueous High Reflective White, available from 
BASF, Inmont Division. As illustrated in FIG. 7, the opacifying and 
reflectivity increasing coating provides a light reflective surface to the 
mailer. This permits ready scanning of addressee information by automated 
sorting equipment as well as providing a light-colored, neutral background 
for receiving endorsement information on the back of the check portion of 
the mailer. 
By "opacifying" we mean a coating which increases the opacity of the 
substrate to light. However, the final product need not be, and in the 
vast majority of cases is not, completely opaque to light. Rather, it is 
desired that the base sheet and cover sheet have a high level of opacity 
which when combined with the camouflage pattern and obscuring coating, 
render printed matter inside substantially unreadable through the mailer 
construction. 
In another embodiment of the invention illustrated in FIG. 2, the preferred 
mailer construction may comprise a single sheet. The form includes a first 
half portion 10 and a second half portion 12. The inner surfaces 20 and 22 
may be printed with indicia such as a combined check and stub. The outer 
surfaces are printed with the camouflaging block out pattern C and 
overcoated with the obscuring and opacifying gray and white coatings D and 
O, respectively. As shown in FIG. 2, the mailer construction includes an 
adhesive 14 applied around the peripheral edges of the mailer and includes 
perforated removable edge portions 18 and perforations 19. The mailer also 
includes a die cut window 16 covered with glassine or other transparent 
material on the first half portion 20. 
In another embodiment of the invention illustrated in FIG. 3, a preferred 
mailer construction is provided which comprises a single sheet continuous 
form which may be used in an automated printing device. The single sheet 
comprises left half portion 20 and right half portion 22 which may be 
folded over to form a single sheet. As will be apparent to one of ordinary 
skill in the art, the printing on the left half portion and right half 
portion of the continuous form may be interchanged. The front surface of 
the single sheet may be printed with indicia such as a combined check and 
stub. The back surfaces of the sheet are printed with the camouflaging 
block out pattern and coated as described previously. As shown in FIG. 3, 
the mailer construction includes an adhesive 14 applied around the 
peripheral edges of the sheet, and includes perforated removable edge 
portions 18 and perforations 19. The mailer also includes a die cut window 
16 covered with a transparent material such as glassine on the left half 
portion of the sheet. For automated printing, the form includes pin feed 
holes 32 in detachable margins 34 extending along both sides thereof. The 
form also includes transverse perforations 36 for separating the 
continuous form into individual mailers. 
In another embodiment of the invention illustrated in FIG. 4, a mailer is 
provided which comprises a cover sheet 10 and a base sheet 12, with an 
indicia bearing sheet 30 positioned between the base and cover sheets. 
Inner surfaces 20 and 22 of the mailer may be printed with indicia as 
well. The outer surfaces are printed with the camouflaging block out 
pattern and coated as described previously. As illustrated in FIG. 4, 
cover sheet 10 and base sheet 12 are secured at their peripheral edges 
with an adhesive 14 and also include perforated removable edge portions 18 
and perforations 19. The cover sheet 10 also includes a die cut window 
which is covered with a transparent material. 
While the confidential information bearing article, and a preferred mailer 
construction, of the present invention has been described with camouflage, 
obscuring, and opacifying and reflectivity increasing coatings on the 
exterior surfaces thereof, the coatings may be applied to respective inner 
surfaces of the article so as to provide clean outer surfaces to the 
article. Alternatively, where there is a high need for confidentiality, 
the coatings may be applied to both the inner and outer surfaces of the 
article. For example, where the article is a lottery ticket, two-sided 
coating will provide a very effective article for maintaining the 
confidentiality of information. In either embodiment, inner surfaces of 
the article may then be overprinted with indicia, including confidential 
information, checks, or other financial instruments. The information 
obscuring coating provides a neutral background for printing while also 
preventing that information from being viewed by holding the mailer up to 
a source of light. 
A summary of a preferred automated process for constructing a preferred 
mailer construction in accordance of the present invention is described 
below. 
A roll of continuous form paper is printed on its back side with a 
camouflaging block out pattern such as the one illustrated in FIG. 5 by 
conventional printing means such as flexographic or gravure printing. The 
paper is then overcoated with a first obscuring coating of an ink of a 
color which aids in hiding the information, also by conventional printing 
means. The obscuring coating is then overcoated with an opacifying and 
reflectivity increasing coating of white ink. The paper is allowed to dry 
and is then rewound. The resulting paper is effectively opaque. That is, 
while the paper is not completely opaque to light, the combination of 
camouflaging pattern, obscuring coating, and opacifying and reflectively 
increasing coatings renders printed information substantially unreadable 
through the paper. 
The continuous paper is then fed through a printing operation where it is 
printed with return address information on its back side and printed with 
any desired interior images on its front side. The paper is then 
perforated around the periphery of the individual mailers outlined on the 
form. If desired, windows are die cut along specific intervals on the left 
half portion of the form and a transparent material such as glassine may 
optionally be applied and glued over the window area. A hot melt adhesive 
is then applied to selected peripheral edges of the individual mailers on 
the form. 
The continuous form paper may then be shipped to a customer or other 
potential user where individual payee and amount information is printed 
onto the front side of the form. The paper may then be fed through a 
document heat sealing device such as the Series 400 Thermobond.RTM. unit 
available from The Standard Register Company. The machine automatically 
feeds in the continuous paper, folds the form in half, and heat seals the 
edges of the form so that it is secured. The forms may then be burst and 
trimmed to separate the individual mailers. 
In order that the coating process of the invention may be more readily 
understood, reference is made to the following examples which are designed 
to illustrate the invention, but not limit the scope thereof. 
EXAMPLE 1 
A gray ink composition for use as an obscuring coating in accordance with 
the present invention was prepared by adding 40% by weight polyethylene 
glycol 400, 5% by weight of a 50% gluconic acid solution, 6% by weight 
tetrahydrofurfuryl alcohol, and 2% by weight Solvent Black 7 in a vessel 
equipped with a mechanical stirrer. The mixture was stirred for 20-30 
minutes at room temperature at moderate speed. Next, 7% by weight 
isopropyl alcohol and 0.5% by weight SWS 213 Defoaner were added to the 
mixture and stirred for another 10 minutes. Water (39.5% by weight) was 
then slowly added while the mixing was continued. The ink mixture was then 
filtered through a 50 micron filter. 
EXAMPLE 2 
A gray ink composition for use as an obscuring coating in accordance with 
the present invention was prepared by adding 15% by weight 
methoxypolyethylene glycol 350, 5% by weight of a 50% gluconic acid 
solution, 6% by weight tetrahydrofurfuryl alcohol, and 2% by weight 
Solvent Black 7 in a vessel equipped with a mechanical stirrer. The 
mixture was stirred for 20-30 minutes at room temperature at moderate 
speed. Next, 7% by weight isopropyl alcohol and 0.5% by weight SWS 213 
Defoamer were added to the mixture and stirred for another 10 minutes. 
Water (64.5% by weight) was then slowly added while mixing was continued. 
The mixture was then filtered through a 50 micron filter. 
EXAMPLE 3 
A gray ink composition for use as an obscuring coating in accordance with 
the present invention was prepared by adding 8% by weight sulfonated 
nigrosine, 10% by weight isopropyl alcohol, 0.5% by weight SWS 213 
defoamer, and 76.5% water by weight in a vessel equipped with a mechanical 
stirrer. The mixture was stirred for 10 minutes at room temperature. The 
ink mixture was then filtered through a 50 micron filter. 
EXAMPLE 4 
A roll of uncoated 24# bond paper was printed with a camouflage image on 
one surface thereof. The printed surface of the paper was then overcoated 
with the obscuring gray ink composition of Example 3. While still wet, the 
paper was then overcoated with an opacifying coating of a light reflective 
white ink available from BASF, Inmont Division, under the designation 
CR37861 Aqueous High Reflective White. The paper was then dried and 
rewound. 
Having described the invention in detail and by reference to preferred 
embodiments thereof, it will be apparent that modifications and variations 
are possible without departing from the scope of the invention defined in 
the appended claims.