Materials and methods utilizing a temporary visual indicator

This invention relates to novel compositions containing temporary visual indicators and methods for using these compositions. Specifically, this invention relates to a sunscreen composition containing an indicator that is visible when the substance is applied to the skin, but becomes invisible shortly after application. The continued presence of the indicator allows the indicator to be reactivated temporarily to the visible form so that a user can verify the presence of the sunscreen. The visible indicator ensures that the sunscreen is applied evenly and completely to the area to be protected, but becomes invisible so as not to interfere with the action of the sunscreen or discolor the skin.

BACKGROUND OF THE INVENTION 
The potentially harmful effects of overexposure to solar radiation are now 
well-documented. These harmful effects range from the discomfort of minor 
sunburn to increased incidences of serious disorders such as skin 
melanomas. A variety of methods for avoiding overexposure to the sun's 
rays have been devised. The use of hats, protective clothing, and other 
physical barriers to block radiation is common. A wide variety of chemical 
compounds are also available which can be used to block or absorb certain 
constituents of solar radiation. Such chemical compounds are widely used 
in suntan compositions. Such suntan compositions may be formulated to 
absorb a major portion of the incident radiation and screen the user from 
the sun's rays or they may be formulated to allow most of the radiation to 
pass through. The consumer can choose an appropriate level of sunscreen 
protection. 
One problem frequently encountered by sunscreen users pertains to the 
difficulty in achieving complete and uniform protection. Uneven or 
incomplete application of sunscreen may result from the difficulty in 
applying lotion to hard-to-reach areas of the body such as the middle of 
the back. The back is not only hard to reach, but it is also hard to see, 
and therefore, it is often difficult to tell accurately where sunscreen 
has been applied. Even for portions of the body which are easy to reach 
and to see, it is often difficult to know where sunscreen has been applied 
because it is either clear as it is applied or it quickly becomes clear as 
it is rubbed into the skin. Thus, a common problem encountered by 
sunbathers or others who use sunscreen is the occurrence of localized 
areas of sunburn caused by the incomplete or uneven application of 
sunscreen. Such overexposure to the sun's rays can result in unattractive, 
uneven tanning and, more importantly, can lead to serious skin disorders 
if the overexposure is prolonged or particularly severe. 
Another common problem faced by sunscreen users is knowing whether the 
sunscreen that had been applied at an earlier time is still present. 
Sunscreens are often formulated to be water-proof or water-resistant, but 
there are no guarantees as to just how water-resistant. Therefore, after 
several trips to and from the water, sunbathers cannot be certain their 
sunscreen has not washed away leaving them unprotected from the sun. 
The subject invention provides, for the first time, an easy means for the 
sunscreen user to know exactly where sunscreen has, and has not, been 
applied and whether already applied sunscreen is still present. The 
technology of the subject invention can also be utilized in other 
situations where it is desired to know where a particular material has 
been applied. Clear lacquers, varnishes or sprays formulated with the 
temporary visual indicator of the subject invention allows the user to 
ensure that an area is adequately covered by these materials by providing 
a temporary color guide for the user during their application. The 
temporary visual indicator of the subject invention formulated with 
pesticides, herbicides or fertilizers guides the user in accurate and 
complete application of these materials to a treated area. In preparing 
for surgery or other medical procedure, it is often necessary or desirable 
to apply a disinfecting, medicated, or analgesic lotion or spray to a 
particular area of the patient. It is advantageous, or critical, to know 
precisely where that lotion or spray has been applied. The temporary 
visual indication of the subject invention ensures the entire surgical 
area is disinfected. 
An adhesive compound which undergoes color changes upon application is 
described in Chandaria, U.S. Pat. No. 4,954,544. The indicator affecting 
the color change in '544 enhances the physical characteristics of the 
composition by contributing to the improved flow and adhesion of the glue. 
The indicator also adds to the economy of the product by allowing the glue 
to be formulated with less adhesive compound. Unlike the indicator in 
'544, the temporary visual indicator of the present invention is 
incorporated into a material exclusively to provide a visual guide for the 
application of that material to a surface. Until now there has been no 
accurate means for knowing the precise location where lotions or other 
like materials have been applied. 
BRIEF SUMMARY OF THE INVENTION 
The subject invention concerns novel methods and compositions useful for 
providing temporary visual indication of the location to which a lotion or 
other material has been applied. The materials and methods of the subject 
invention are specifically exemplified with reference to sunscreen, but a 
person of ordinary skill in the art would readily appreciate that the 
teachings of the subject invention can be readily applied to other 
technologies. 
Specifically exemplified herein are sunscreen compositions which contain a 
visual indicator allowing the sunscreen user to know exactly where the 
sunscreen has been applied. Advantageously, the visual indicator provided 
according to the subject invention is visible only temporarily and 
disappears within a short period of time so as not to interfere with the 
transparent nature or activity of the sunscreen. As described herein, the 
compositions of the subject invention can be formulated by a person 
skilled in the art, using the teachings of the instant invention, to 
permit the indicator to remain visual for a period of time appropriate for 
the particular application. For example, in the case of sunscreen the 
indicator may remain visual for about 15 seconds to 2 minutes or more 
after the initial application of the lotion and for only 30 seconds to 1 
minute upon reactivation of the indicator. 
In a preferred embodiment of the subject invention, a sunscreen is 
formulated with a compound which is visible at a first pH and invisible at 
a second pH. The sunscreen is formulated at said first pH, wherein the 
indicator is visible but, upon application to the skin, the sunscreen 
changes pH, within a short period of time, to said second pH, wherein the 
indicator can no longer be seen. The indicator can be reactivated to its 
visible form by temporarily returning the pH of the lotion already applied 
to the skin to the first pH to verify the continued presence of the 
sunscreen. As a specific example, the visual indicator useful according to 
the subject invention can be phenolphthalein which is pink and can be seen 
at a pH of 9.0 and above, but is invisible or colorless at a pH below 8.5. 
The sunscreen composition containing phenolphthalein can be formulated 
with a volatile base, eg. ammonia, such that the composition has a pH 
greater than 9.0 when applied, but becomes neutral after a short period of 
time because of the evaporation or degradation of the base. Thus, the 
phenolphthalein is initially visible, but within a short period of time 
will disappear. The phenolphthalein in the sunscreen can be reactivated 
temporarily by reapplying the volatile base. 
The technology can be applied to other situations or compositions where a 
visual indicator is needed temporarily.

DETAILED DESCRIPTION OF THE INVENTION 
The subject invention concerns novel methods and compositions useful for 
providing a temporary visual indication of the location to which a lotion 
or other material has been applied. As used herein, the term lotion 
includes creams, gels, ointments and solutions. In the preferred 
embodiment, the lotion is a sunscreen. A temporary visual indicator 
formulated with a sunscreen has the advantage of allowing the user to 
apply the sunscreen evenly over the areas to be protected as well as 
completely so that no areas are left unprotected. Reactivation of the 
indicator with a disclosing solution allows the user to check whether the 
sunscreen is still present on the skin and protecting the sunbather from 
the harmful rays of the sun. The visual indicator disappears after a 
matter of minutes so as not to interfere with the sunscreen's activity or 
stain or discolor the skin or clothing. 
A temporary visual indicator formulated with all types of suntan products 
provide a similar advantage. Suntan products are not only those 
compositions that prevent sunburn, eg. sunscreen, but also are those 
compositions that cause or create a tan. Suntan lotions or oils which 
cause tanning formulated with a temporary visual indicator ensure the user 
an even tan making sure all areas of the skin are covered. The temporary 
indicator formulated with a product that creates an artificial tan 
provides the user with a visual guide so that the "tan" is applied 
completely. Additionally, the color intensity of the indicator varies with 
the amount of product applied to the skin therefore, a user is certain to 
apply the "tan" evenly. 
The temporary visual indicator of the subject invention formulated into 
other compounds also results in advantageous compositions and methods. For 
example, a temporary visual indicator formulated with topical 
dermatologicals ensures that the medication is evenly and completely 
dispensed over the entire affected area. The color intensity of the 
indicator varies with the amount of medication applied. Therefore, the 
indicator serves to guarantee the proper amount of medication is applied 
to the treated area. A temporary visual indicator formulated with a 
surgical scrub ensures that the area being disinfected is completely 
scrubbed. Surgical scrubs often contain iodine as a disinfecting agent. 
The iodine in the scrub stains the skin on contact so that the iodine 
serves as a color guide for application as well as a disinfecting agent to 
ensure the area is completely scrubbed. Iodine, however, has fallen into 
disfavor for use in surgical scrubs. Iodine has been found to support the 
growth of certain bacterial pathogens. Additionally, iodine has been found 
to be toxic to dermal cells thereby impeding the healing of surgical 
incisions. The temporary visual indicator of the present invention is not 
toxic to dermal cells. Furthermore, the temporary nature of the indicator 
provides that no color is left on the skin to interfere with surgical 
marks to be used in the procedure. 
The visual indicators of the subject invention can be used to improve the 
utility of a variety of products. For example, the accuracy of a spray is 
often unreliable; threrefore, a temporary visual indicator formulated with 
an antibacterial spray is quite advantageous because the temporary visual 
indicator makes certain that the entire infected area is treated. 
Similarly, a temporary visual indicator formulated with dental sealants 
ensures that the entire tooth is covered and adequately sealed. In 
ophthalmic solutions, a temporary visual indicator verifies adequate 
administration of the solution to the eye, yet does not interfere with 
sight after the indicator turns colorless. 
The temporary visual indicator of the subject invention can be formulated 
with other products which require proper and complete coverage of a 
surface. A temporary indicator formulated with paints, varnishes, or 
lacquers guarantees adequate coverage of a surface. When applying a second 
coat of paint, the temporary visual indicator ensures that fresh paint is 
applied to the entire painted surface so that paint will not dry unevenly 
or blotchy. In working with clear finishes such as lacquers or varnishes, 
it is often difficult to tell which areas have or have not been covered. 
The temporary indicator provides a color guide while the finish is being 
applied which rapidly disappears so that the clear finish properties of 
the compound are retained. Car polish or other polishes formulated with a 
temporary visual indicator ensure complete coverage of the car with the 
polish, but do not stain or discolor the finish of the car. 
The temporary visual indicator of the subject invention formulated with 
certain products ensures that these products are accurately applied. The 
color guide provided by the temporary visual indicator formulated with a 
grease compound not only ensures that an area is adequately greased, but 
also ensures that other components are not soiled by the grease compound. 
Teflon sprays and coatings which are difficult to remove if misapplied are 
accurately applied when formulated with a temporary visual indicator. 
A temporary visual indicator formulated into protective sealants ensures 
that an area is completely sealed and protected. Fabrics and carpets are 
often treated to protect against stains. These textiles sometimes have 
intricate weaves or deep naps and it is difficult to be sure that all 
areas of the fabric are adequately treated. A temporary visual indicator 
formulated in protective sprays provides the user with a color guide for 
applying the protectant so that the user is sure that even recessed areas 
of a weave are protected from stains. A temporary visual indicator 
formulated into sealants such as waterproofing agents for wooden decks 
allows the user to be sure that the deck in fully sealed. The temporary 
nature of the indicator, however, ensures that the sealant will not mask 
the grain or stain the wood. 
A temporary visual indicator formulated with pesticides, herbicides or 
fertilizers ensures adequate treatment of all areas with the compound. 
Uneven greening of a plant caused by disproportionate coverage of the 
plant with a pesticide is avoided. The indicator formulated with a 
pesticide for in-home use does not stain floors, walls or woodwork to 
which the pesticide is applied. The presence of the indicator not only 
ensures that the pesticide is adequately applied, but also ensures that 
the pesticide is accurately applied. The color guide provided by the 
temporary indicator guarantees that children's toys, plants or pet dishes 
lying on the floor are not mistakenly sprayed with the pesticide. Pots, 
pans, utensils, and food items within cabinets and drawers being treated 
will likewise be protected from the effects of stray pesticide. Items that 
are mistakenly sprayed are immediately identifiable and can be washed to 
remove the pesticide. The volatile base can be applied to the washed item 
to verify no residual pesticide is present. 
Herbicides formulated with the temporary visual indicator allow for 
selective application of the product to plants. The herbicide 
N-phosphomethyl glycine, (glyphosate), is a broad-spectrum, non-selective 
herbicide that kills virtually all vegetation it contacts. Selective 
application is essential. The temporary visual indicator formulated with 
this herbicide provides a color guide for application of the herbicide so 
that only those plants that need to be treated are treated and that 
treated plants are fully sprayed. Herbicides applied in the wind or under 
conditions created by a fan in a greenhouse are accurately applied when 
formulated with the temporary visual indicator of the subject invention. 
The indicator formulated in cropdusting compounds will ensure the delivery 
of the herbicide is complete and on target. Fertilizers formulated with a 
temporary visual indicator ensures that the soil to which they are applied 
is adequately covered. 
The temporary indicator of the subject invention can be used in security 
situations where the colorless state of the indicator conceals the 
presence of the indicator. The colorless indicator sprayed on a surface is 
undetected by someone tampering with the surface, but shows signs of being 
disturbed when the indicator is treated and becomes visible. The person 
tampering with the surface also picks up indicator of their hands. The 
indicator can be detected on the hands of the perpetrator after treatment 
with a disclosure solution allowing the indicator to be visualized. An 
invisible hand stamp containing the temporary visual indicator which 
becomes visible upon treatment serves as an alternative to present 
UV-visible technology. 
In a preferred embodiment, phenolphthalein is used as the indicator. Other 
suitable indicators may be found in U.S. Pat. No. 4,954,544. 
Phenolphthalein, 3,3-bis[4-hydroxyphenyl]-1-[3H]-isobenzofuranone, is 
colorless in its lactone form, the form present in solutions below pH 8.5. 
In solutions above pH 9.0, the lactone form of the molecule loses two 
protons to form an intensely colored red dianion. Sunscreen formulated at 
a pH above 9.0 is colored pink, or red, by the phenolphthalein. When the 
pH of the sunscreen drops below pH 8.5 the sunscreen is clear. The 
continued presence of the phenolphthalein in the sunscreen causes the 
sunscreen to turn pink should the pH of the sunscreen be raised to a pH 
above 9.0 again. 
The temporary nature of the visual indicator of the subject invention is 
due to the selection of a volatile component. For example, when 
phenolphthalein is used as the visual indicator, a volatile base can be 
used to raise the pH of the sunscreen containing the phenolphthalein to 
above 9.0. At that pH, phenolphthalein is in its red dianion form and the 
sunscreen is colored red or pink by the indicator. On application of the 
pink sunscreen to skin, the volatile nature of the base causes the base to 
evaporate or dissipate rapidly. As the base evaporates, the pH of the 
sunscreen falls below pH 8.5, phenolphthalein returns to its colorless, 
lactone form and the sunscreen is no longer colored by the indicator. A 
mild solution of the volatile ammonia can later be sprayed onto the skin 
to temporarily raise the pH of the sunscreen above pH 9.0 and reactivate 
the indicator to the red dianion form. Volatile bases appropriate for use 
in the subject invention include, but are not limited to, monoamines such 
as ammonia, methyl amine, ethyl amine, isopropyl amine, butyl amine, 
pentyl amine, hexyl amine and octyl amine, diamines such as ethylene 
diamine, 1,2-diaminopropane, 1-3-diaminopropane and 1,2-diaminobutane or 
cyclic amines such as tetrahydropyrrole. Of the volatile bases listed 
above, ammonia and pentyl amine are currently used as inactive ingredients 
in marketed drug products. 
Although phenophthalein and a single volatile base are exemplified in the 
preferred embodiment, other indicators, alone or in combination, and other 
physical and chemical reactions effecting a color change and providing a 
temporary visual indication of the location a lotion or like material is 
applied are also embodied by this invention. Furthermore, more than one 
volatile component may be formulated into a product containing an 
indicator. For example, in a sunscreen composition, a first volatile base 
which evaporates rapidly provides the user a color guide for application, 
and a second volatile base affecting the same or different indicator which 
evaporates more slowly signals the user it is time to reapply the 
composition. As used herein, and throughout the claims, the term "color" 
includes colors of all shades, hues and intensities visible to the eye. 
Indicators such as bromthymol blue and thymol blue each operate as 
indicators within a pH range applicable to the sunscreen embodiment. Both 
indicators are blue under basic conditions and yellow under neutral 
conditions. The sunscreen on the skin need not be invisible as long as the 
color remaining is not objectionable to the user. Color changes of an 
indicator may be triggered by a variety of physical or chemical reactions. 
The presence of certain gases, changes in temperature or exposure to UV 
light may all be used in methods to effect color changes of certain 
indicators. For example, the materials and methods of the subject 
invention can be used to create greenhouse windows that darken 
automatically as the temperature increases. Boron-amine complexes will 
dissociate at elevated temperatures. The free amine molecules increase the 
pH of the surrounding area and trigger a color change of the indicator 
thereby darkening the windows. 
Formulation of the lotions or other materials with the temporary visual 
indicator of the subject invention can be done utilizing materials and 
methods well-known and readily available to those skilled in the art. The 
indicator must be present in an amount sufficient to provide an adequate 
visual signal when exposed to the base, but should not be present in such 
a quantity that will affect the qualities of the lotion or other materials 
in which it is formulated. Suitable compositions of the present invention 
contain not more than 10% by weight and preferably from 0.001% to about 2% 
by weight of the indicator. The volatile base needs to be present in an 
amount sufficient to change the pH of the entire composition to a level 
that will affect the indicator and be present in an amount sufficient to 
maintain that pH for an adequate time after the lotion is applied. The 
volatile base must not be present, however, in amounts that cause the pH 
of the lotion to be so high that it damages the areas to which the lotion 
and/or base is applied. Volatile bases are selected with respect to their 
rate of evaporation. Volatile bases must also be selected with regard to 
their acceptability as components of pharmaceutical compounds and with 
respect to their toxicity. 
Following are examples which illustrate procedures, including the best 
mode, for practicing the invention. These examples should not be construed 
as limiting. All percentages are by weight and all solvent mixture 
properties are by volume unless otherwise noted. 
EXAMPLE 1 
Indicator Sunscreen Lotion Formulation 
The indicator sunscreen lotion of the subject invention may be formulated 
using commercial sunscreen products as follows: 
______________________________________ 
Commercially available sunscreen product 
50 ml 
(Treasury Brand SPF-4) 
Phenolphthalein 100 mg 
1,3 diaminopropane 0.5 ml 
______________________________________ 
EXAMPLE 2 
Disclosing Solution for the Indicator Sunscreen Lotion 
The disclosing solution of the subject invention may be formulated as 
follows: 
______________________________________ 
1,3 diaminopropane 
10 ml 
Water 90 ml 
______________________________________ 
It should be understood that the examples and embodiments described herein 
are for illustrative purposes only and that various modifications or 
changes in light thereof will be suggested to persons skilled in the art 
and are to be included within the spirit and purview of this application 
and the scope of the appended claims.