Abstract: By preliminarily measuring the gallium temperature and the length change of a temperature sensing element comprising a carbon nanotube having a continuous column of gallium contained therein, then heating the temperature sensing element installed in a subject to increase the temperature thereof in air, removing the temperature sensing element subjecting to measure the gallium length, and substituting the measured gallium length in a formula, the temperature is measured accurately over a wide temperature range in a micrometer size or less environment.

Abstract: A full-history time-temperature indicator system which is capable of exhibiting a time-temperature dependent and visually detectable chemical reaction, useful for monitoring the time and temperature exposure of food products. The system comprises an immobilized reactant, such as Fe3+, and a mobile reactant, such as Fe(CN)64-, initially contained in separate compartments, and separated by a sealing. The system is activated by removing a sealing between the compartments whereby the mobile reactant in a time-temperature dependent manner is brought into contact with the immobilized reactant resulting in a visually detectable reaction signal.

Abstract: A shape memory material activated device of the present invention uses a shape memory material activator to create a path through a shell wall of the device. The path through the shell wall may release a substance contained in the shell or allow a substance to enter the shell. The path may be created by fracturing, puncturing, exploding, imploding, peeling, tearing, stretching, separating, debonding or otherwise opening the shell. The devices according to the present invention may be used as temperature sensors or warning devices, drug delivery devices, and the like.

Abstract: A simple recording device using a stable electric resistance heater in thermal contact with an irreversible color changing time temperature material relatively insensitive to room temperatures to show and record the cumulative time an electrical appliance, battery, tool, instrument has been used. The device may use a plurality of thick film carbon printed resistive heater with a thermal gradient in contact with the time temperature material or a simple adhesive calibrated time temperature film on a surface mounted stable resistor. The indicator is in parallel or series with the power switch. The time temperature material is in thermal contact with a constant temperature heater when used in fluctuating ambient temperature conditions.

Abstract: A temperature sensitive piece 9 has a waxed layer 7 formed on a colored face 4 of a colored paper 6 having an arbitrary plane shape. The waxed layer 7 is formed of a mixture of a proper amount of viscous material and powdered petroleum wax melting at selectively preset temperature. The temperature sensitive piece 9 is affixed to a sheet-shaped base 1 with the waxed layer 7 being located close to the front face of the temperature sensor label. The entire face of the base 1 facing the front face of the temperature sensor label is covered with a transparent film 5.

Abstract: A device and method of making a device for indicating a change in condition is disclosed. A first embodiment is a device for indicating a transition from a frozen condition to a thawed condition is disclosed. The device includes a housing and a capsule. A first reactant and a liquid are included within the capsule. The liquid is chosen such that it expands upon freezing. The capsule is sized such that when the liquid freezes and expands, the capsule fractures. A second reactant is provided within the housing. The location of the second reactant and the method of attaching (if any) the second reactant to the housing may take various forms. When the liquid within the capsule freezes, it expands and fractures the capsule. Upon thawing, the reactant within the capsule escapes and mixes with the reactant located outside the capsule. A second embodiment is a time-temperature indicator. A flexible housing is used, allowing the user to manually deform the housing to fracture a capsule enclosed therein.

Abstract: The invention is a method of monitoring the temperature to which an object has been exposed. The invention comprises combining a Time-Temperature Indicator (TTI) with an electronic monitoring device to determine whether the temperature to which the object has been exposed may have exceeded a predetermined threshold. The TTI device can be used to make a rapid initial determination as to the acceptability of the temperature history. The temperature history stored in the electronic monitoring device can be retrieved if visual inspection of the TTI indicates that the temperature history may possibly have exceeded the predetermined threshold. As a result, rejection of goods based on inaccurate TTI readings can be reduced or prevented, and the amount of time needed to retrieve data from an electronic monitoring device can be limited to only those circumstances where the initial visualization of the TTI indicates the possibility of an unacceptable temperature history.

Abstract: The inventive device comprises a housing (1) which is configured in the shape of a flat strip comprising an enclosure (6) on one side which projects outwards and contains a material (7) that changes its state or viscosity at a predetermined temperature. Said enclosure (6) opens onto the space inside the housing through a hole (8) which can be plugged with a tongue (9), this space inside the housing containing a strip (11) consisting of a porous material that is visible form the outside through holes made on the top surface (5) of the housing.

Abstract: Thermal indictors of this invention are constructed for use with a heat exchanger generally comprising hot and cold side passages for accommodating a desired heat transfer therebetween. The thermal indicator is disposed at least partially within the heat exchanger and is formed from a material designed to undergo a permanent physical change when exposed to a temperature that is above a heat exchanger design operating temperature.

Abstract: A product shelf life monitoring system comprising an active substituted diacetylenic monomer component indicator composition is responsive to an integral of varying temperature over time to effect a solid state polymerization in the active monomer which results in a visible change in color density or the like at a rate designed to closely approximate the degradation, or shelf life, of an associated foodstuff or medicament product. The reactivity of the monomer component upon which the time-temperature integral of the indicator composition, and thus the represented shelf life, primarily depends may be readily varied by refluxing a solution of the monomer in a selected solvent for a predetermined time prior to recrystallization of the monomer for incorporation into the indicator composition.

Abstract: Time or time-temperature indicating articles are described comprising a housing enclosing: (a) a first fluid reservoir at least partially filled with a first fluid; (b) a substrate comprising a plurality of channels; (c) a second fluid reservoir in fluid communication with at least one channel of the substrate; and (d) a barrier located between the first fluid reservoir and the second fluid reservoir. The article can be manipulated at a desired point in time by opening the barrier to allow at least a portion of the fluid to flow from the first reservoir to the second reservoir and to contact at least one channel of the substrate. The article is designed to provide an indication of the progress of the fluid as it moves through the channels of the substrate.

Abstract: The temperature indicating surface, typically a label, includes an irreversibly fusible coating which changes from a first appearance to a second appearance in response to exposure to a threshold temperature or rated temperature. An in situ standard is provided by initially fusing selected areas of the temperature indicating surface so that a pattern is visible prior to exposure to the threshold temperature. Upon exposure to the threshold temperature, however, the entire temperature indicating surface is fused thereby presenting a uniform appearance and unambiguous evidence of prior exposure to the threshold temperature.

Abstract: In a data carrier (1) having an electrical circuit (2), indication means (3) are implemented by means of the electrical circuit (2), which means are arranged so as to determine the occurrence of a change in a parameter influencing the data carrier (1) in relation to at least one threshold value, the at least one threshold value dividing a first parameter range from a second parameter range, and which means are arranged so as to give a permanent indication of the change during the time following the first occurrence of said change.

Abstract: A lambda sensor for motor vehicles which permanently displays an at least temporary thermal overload by means of an indicator which, for fast reliable and unambiguous diagnosis without major additional measurement effort or expense, includes an indication material having at least one limit temperature adapted to the maximum allowable operating temperature of the component, and when this limit temperature is exceeded in at least one material component, a microstructural change ensues.

Abstract: A device and method of making a device for indicating a change in condition is disclosed. A first embodiment of the device includes a housing and a capsule. A first reactant and a liquid are included within the capsule. The liquid is chosen such that it expands upon freezing. The capsule is sized such that when the liquid freezes and expands, the capsule fractures. A second reactant is provided within the housing. The location of the second reactant and the method of attaching (if any) the second reactant to the housing may take various forms. When the liquid within the capsule freezes, it expands and fractures the capsule. Upon thawing, the reactant within the capsule escapes and mixes with the reactant located outside the capsule. A second embodiment is a time-temperature indicator, which uses a flexible housing to allow manual deformation of the housing to fracture a capsule enclosed therein.

Abstract: A sensor of a parameter such as temperature includes an indicator encapsulated within a rigid enclosure, wherein the sensor has a characteristic that varies with the parameter that is detectable upon illumination with electromagnetic radiation through a window of the enclosure that is transparent to the radiation. In a specific example, the indicator changes an optical characteristic such as its color as a function of its temperature, and may be of an irreversible type in order to indicate the peak temperature reached. The sensor may include a pattern of such indicators that have different peak temperatures to which they respond, so that the sensor gives a unique visual pattern at each temperature within its measurement range. This pattern may be viewed directly or processed by computer to compare the pattern with those which indicate known temperatures.

Abstract: An irreversible temperature indicating paint comprises 25 wt % to 50 wt % cobalt silicate, 0 wt % to 20 wt % alumino silicate, 0.5 wt % to 5 wt % toluidine red, 25 wt % to 40 wt % acrylic resin and 10 wt % to 20 wt % silicone resin excluding solvent. The solvent comprises a mixture of 80% 1-methoxy-2-propanol and 20% dipropylene glycol monomethyl ether. The irreversible temperature indicating paint has at least five colour changes in the temperature range 1050° C. to 1350° C. A particular irreversible temperature indicating paint comprises 33.8 wt % cobalt silicate, 16.9 wt % alumino silicate, 2 wt % toluidine red, 30.8 wt % acrylic resin and 16.5 wt % silicone resin excluding solvent. The irreversible temperature indicating paint is used to determine the temperatures to which various parts of turbine blades, turbine vanes or other components are subjected in operation of the gas turbine engine.

Abstract: Recording materials are converted in a direct thermal imaging apparatus to time temperature indicators by exposure to heat from the thermal print head of a direct thermal printer. Methods for converting a recording material to a time temperature indicator comprise heating the recording material with a direct thermal imaging apparatus. The recording material contains an indicator compound which is convertible from an inactive state to an active state when heat is applied thereto by a direct thermal imaging apparatus for less than one second. Time-temperature indicators with active indicator compounds in a printed pattern are formed by a direct thermal imaging apparatus.

Abstract: A time-temperature indicator device comprises a polymeric layer having a first and second surface and a dye composition adhered to said first surface comprising a dye which diffuses into the polymeric layer as a result of a cumulative time-temperature exposure wherein the polymeric layer is formed from a natural or synthetic rubber polymer or copolymer. The device may be attached to a product for monitoring cumulative time-temperature exposure.

Abstract: An x-ray system 20 includes an x-ray tube insert (24) that has an evacuated envelope (34), an anode assembly (38) and a cathode assembly (40). The anode assembly (38) and the cathode assembly (40) are located in operative relationship to one another within the evacuated envelope (34). A temperature indicating member (100) is located in thermally conductive contact with at least one assembly (38, 40, 66) located in the x-ray tube insert (24). The temperature indicating member (100) has a temperature sensitive characteristic which changes in response to adequate thermal exposure to at least one temperature threshold value.

Abstract: A time-temperature indicator device provides a visually observable indication of the cumulative thermal exposure of an object. The device includes a substrate having a diffusely light-reflective porous matrix and a backing. The backing includes on its surface a viscoelastic indicator material for contacting the substrate and a barrier material for substantially inhibiting the lateral and longitudinal flow of viscoelastic indicator material between the substrate and the backing.

Abstract: A temperature indicating device utilizing a housing having an exterior and an interior which includes first and second chambers. First and second chambers communicate with one another. An opening through the housing allows communication between the interior and exterior of the housing. A bimetallic element which is capable of assuming first and second configurations is positioned within the second chamber. A movable member is found in the first chamber and contacts the bimetallic elements when the bimetallic elements assumes the first configuration. A spring bias the contact between the movable member and the bimetallic element and urges movement therebetween when the bimetallic element assumes the second configuration. A signal indicates such movement by utilization of the opening between the exterior and interior of the housing.

Abstract: Temperature control is carried out with a temperature control material comprising a temperature indicator whose developed color density differs according to temperature, which is irreversible at environmental temperature, which changes its color according to crystal or non-crystal, or phase separation or non-phase separation, and whose glass transition temperature is set to a temperature higher than control temperature, by irradiating the temperature indicator with light having a wavelength absorbed by a color developed by the temperature indicator and detecting the intensity of the reflected light or transmitted light. Accordingly, even when the temperature becomes higher than control temperature temporarily, temperature control can be carried out smoothly thereafter.

Abstract: A time-temperature indicator device provides a visually observable indication of the cumulative thermal exposure of an object. The device includes a substrate having a diffusely light-reflective porous matrix and a backing. The backing includes on its surface a viscoelastic indicator material for contacting the substrate and a barrier material for substantially inhibiting the lateral and longitudinal flow of viscoelastic indicator material between the substrate and the backing.

Abstract: A roofing membrane heat seal indicator provides a positive, visually perceptible indication that a joint or seam has been raised to a sufficiently high temperature to achieve a proper seal. The heat seal indicator is applied adjacent and parallel to an edge of a roofing membrane which will be arranged on a roof to form the upper (exposed) surface of an overlapping membrane seam. As the adjacent surfaces of the overlapped membranes are heated, heat passes through the membrane to the heat seal indicator. The heat seal indicator may be a temperature sensitive ink pigmented with material that changes color upon being subjected to a temperature indicating that the membrane surface has been subjected to a sufficiently high temperature to achieve an appropriate seal. Alternatively, the indicator may be an adhered layer of a ground or flaked polymer, such as polyethylene, which is initially opaque but melts to become translucent, thereby indicating obtainment of a proper sealing temperature.

Abstract: A time-temperature indicator label for measuring the length of time to which a product has been exposed to a temperature above a pre-determined temperature is provided. The period of time of exposure is integrated with the temperature to which the indicator is exposed. The label is a composite of a plurality of layers adapted to be adhered at its underside to a product container. The label includes a printable surface layer, a longitudinal wicking strip that is adhered underneath the surface layer substantially at the opposite extremities only of the wicking strip and a lower substrate layer forming an envelope with said surface layer. A heat-fusible substance, which melts and flows above a pre-determined temperature, is applied on the surface of the wicking strip contiguous to at least one of the ends of the wicking member. When the heat-fusible substance is exposed to a temperature above the pre-determined temperature, the heat-fusible substance flows along the length of the wicking member.

Abstract: A temperature sensing device for permanently indicating when a product is exposed to ambient temperatures exceeding a maximum permitted temperature of the product for a time period long enough to permanently damage the product. In an exemplary embodiment, the temperature sensing device is typically located on the protective cover of a battery away from terminals and the battery casing. The temperature sensing device is made of a material to permanently expand and/or shrink upon reaching critical temperatures (e.g. too hot). The expansion is visually detectable by means of a visual indicator and/or reference point.

Abstract: Temperature probes are provided comprising a porous or permeable substrate into which is absorbed at least at the surface a diyne monomer. The absorption is achieved by employing a solution of the diyne monomer in a solvent which is transported by the solid substrate. After impregnation of the substrate, the diyne is polymerized to provide a blue product, which upon being heated above a transition temperature turns to red. Various substrates and devices may be employed for a variety of situations requiring a determination of the occurrence of a particular minimum temperature.

Abstract: A method and a device for monitoring the handling conditions of at least one object intended to be handled under certain predetermined conditions. The temperature or the temperature as a function of time of at least one object, is monitored to enable it to retain as much as possible of its original quality. To this end, a device is inserted into the object, or between two objects in a stack of objects, including a substantially flat, elongate casing, having a slot-shaped space between two opposed walls of the casing. An elongate slide-shaped body removably inserts into the slot-shaped space of the casting. At one end the slide-shaped body is provided with a technique for indicating, by color change, the exceeding and the falling-short of the predetermined conditions. The color change is thereafter observed visually by withdrawing the slide-shaped body removably inserted in the slot-shaped space of the casing.

Abstract: A temperature-time-pressure detecting device for a closed heat treatment zone consists of a sealed discoidal-shaped capsule of substantially transparent material adapted for placement within the zone in a generally vertical position. The capsule is formed of two opposed preferably symmetrical circular shell walls sealed around their common rim and defining therebetween a central core region containing a shaped mass of a fusible indicating material having a defined melting point at least as high as the temperature to be detected. The central core region is surrounded by an inner and an outer annular chamber which are concentric with the core region and with one another.

Abstract: A method of indicating a time or a temperature-time accumulated value as a color change (degree of color development), which comprises providing an oxidation-polymerizable dyestuff and the oxidizing agent in a non-contact state and bringing the oxidation-polymerizable dyestuff and the oxidizing agent into contact with each other to polymerize the oxidation-polymerizable dyestuff with the passage of time, and an indicator material therefor.

Abstract: An inflator which generates gas and heat as the inflator is actuated. The inflator includes an identifying member. The identifying member is provided on the inflator so as to permit the identification of an unactuated state and an actuated state of the inflator on the basis of heat generated during the actuation of the inflator.

Abstract: A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

Abstract: A time-temperature indicator label for measuring the length of time to which a product has been exposed to a temperature above a pre-determined temperature is provided. The period of time of exposure is integrated with the temperature to which the indicator is exposed. The label is a composite of a plurality of layers adapted to be adhered at its underside to a product container. The label includes a printable surface layer, a longitudinal wicking strip that is adhered underneath the surface layer substantially at the opposite extremities only of the wicking strip and a lower substrate layer forming an envelope with said surface layer. A heat-fusible substance, which melts and flows above a pre-determined temperature, is applied on the surface of the wicking strip contiguous to at least one of the ends of the wicking member. When the heat-fusible substance is exposed to a temperature above the pre-determined temperature, the heat fusible substance flows along the length of the wicking member.

Abstract: A thaw indicator unit for sensing and permanently recording a thawing event experienced by a temperature sensitive food or other item, the unit having a container of transparent, non-toxic material, and having a hermetically sealed chamber containing a frozen color change medium having at least two segments of differently colored frozen aqueous compositions, the segments being juxtaposed along an interface of molecular thickness, and at least one of the segments being substantially homogeneously colored differently from at least one juxtaposed other colored segment, wherein the colorants are food grade materials, and whereby the unit when placed on, in or in close proximity to the item will record any first thawing event by way of thawing of the juxtaposed segments and intermixing thereof at least at the interface thereof to produce at least a visible section of an intermix of said compositions and having a markedly different and readily visible color from that of the juxtaposed segments.

Abstract: Temperature probes are provided comprising a porous or permeable substrate into which is absorbed at least at the surface a diyne monomer. The absorption is achieved by employing a solution of the diyne monomer in a solvent which is transported by the solid substrate. After impregnation of the substrate, the diyne is polymerized to provide a blue product, which upon being heated above a transition temperature turns to red. Various substrates and devices may be employed for a variety of situations requiring a determination of the occurrence of a particular minimum temperature.

Abstract: A time-temperature monitor is provided that is adapted for indicating the amount of accumulated time during which the ambient temperature adjacent to the monitor is above a predetermined temperature. The time-temperature monitor comprises a viscous, non-Newtonian fluid biased within a flow path defining element, with the rate of flow therethrough being regulated by a constricting orifice disposed in a nozzle that is positioned in fluid communication with the flow path defining element.

Abstract: A rope including a heat sensitive component which is subject to a visible change in appearance, such as a color change, when exposed to a selected elevated temperature resulting from a strain-related heat release from the rope. The heat sensitive coating may be contained in a coating over a fiber of the rope or a rope strand, or may be incorporated in sheath located over the load-bearing core of the rope.

Abstract: A marking element for indicating whether a pre-defined temperature condition has been maintained. The marking element comprises a first material capable of flowing above a predetermined temperature separated from a second absorbent material by a barrier layer. The first and second materials are such that when the barrier layer is punctured and the predetermined temperature is exceeded the first material flows along the second material to produce a detectable change.

Abstract: An apparatus for checking deep-frozen food, which irreversibly indicates if an additional storage temperature has been exceeded, is described. A flat plastic bag having transparent walls, into which eutectic mixture having a liquid/solid phase transition in the range from 0.degree. to -50.degree. C. has been introduced, together with a magnetic dispersion consisting of finely divided magnetic pigments, has a heat-conducting connection to the material to be frozen. A magnetic stripe which contains a magnetically recorded pattern and which remains connected to the bag until the indicating apparatus together with the material to be frozen has been cooled below the limiting temperature is stuck to the bag. The magnetic stripe is then removed. If the permissible limiting temperature is exceeded, the optically or magnetically readable structure produced by the magnetic stripe in the indicator bag is eliminated, permitting easy checking of the deep-frozen food.

Abstract: An indicator device indicates that the temperature in a location in which the device is placed has exceeded a predetermined maximum temperature value. The he device includes a liquid receptacle comprising frangible bulb portion and an integral capillary portion and an absorbent card to which said receptacle is secured. The bulb portion contains a first liquid and the capillary portion contains a second liquid which is insoluble in said first liquid. The second liquid has a freezing point higher then that of the first liquid and close to but greater than the predetermined temperature value so that when the device is placed in a location which has temperature lower than the predetermined value and in which the predetermined value is to be maintained, the second liquid freezes in the capillary tube and prevents the first liquid from expanding.

Abstract: An improved steam sterilization process monitor is disclosed comprising a backing strip, a wicking means in intimate contact with an organic compound mounted on the backing strip and a water vapor rate controlling cover strip. In the preferred embodiment the backing strip comprises aluminum foil having a polypropylene interlayer adhesively bonded thereto. The sole means for bonding the cover strip to the backing strip is by heat sealing. The cover layer is heat sealed to the backing strip over the entire land area of the backing strip surrounding the wicking means, but is not heat sealed to the wicking means. The organic compound has a normal melting point in the absence of water vapor of about 5.degree. to about 50.degree. F. above a predetermined control temperature.

Abstract: This device comprises a casing (2) of synthetic material containing a motor element (7) made of at least one alloy which memorizes its shape and having associated with it a movement transmission element consisting of a piston (9) and a rod (10) and acting on at least one indicator element (4) irreversibly recording each overstepping of a predetermined temperature, the casing being provided with transparent windows permitting the state of the indicator element or elements to be viewed.Application to the monitoring of the overstepping of a temperature.

Abstract: A check sample of a deep-frozen product or a product is provided, whose keeping, conserving or preserving temperature, which is below ambient temperature, must be controlled or checked. The sample includes a case or envelope, which is sealed in an inviolable manner and, in the case or envelope, a meltable object having a predetermined shape different from the internal shape of the case. This object has a melting point below or equal to the thawing or keeping temperature of the product and the initial shape of the object is impossible to reconstitute following thawing or reheating, even of a partial nature, of the product. According to the invention, the case comprises a first part made invisible and integral with the product or a pack containing the latter by insertion into the pack or the case a second part, which is visible and integral with the first part.

Abstract: A dual temperature indicator providing visual indications when exposed to predetermined high or low temperatures. The indicator has a bulb with a capillary tube and an attached high temperature indicator structure. The bulb has a first liquid which also fills a predetermined portion of the tube. A separating substance and a second miscible liquid further fills a predetermined portion of the remainder of the tube. At a predetermined low temperature, the liquid in the bulb contracts causing the separating substance and a portion of the second liquid to move into the bulb to produce a visible color change. The high temperature indicator structure has an indicating member in contact with the capillary tube end and which provides a visual indication at a predetermined high temperature when the liquids expand upon an environmental temperature increase.

Abstract: A new and improved integrating indicator system operable to signal the attainment of one or more preselected time-temperature integrals which monitor the temperature and time history of a product utilizes a dual system of specific reaction pairs which simultaneously generate acid and alkali from two neutral substrates. One of the substrates is present in excess of the other. The preferred dynamic indicator system generates a constant pH buffer in the alkali range that is maintained until one of the substrates is depleted. At that time, a rapid pH change in the indicator solution to the acid range occurs, resulting in a very sharp visual color change in a pH-sensitive dye. In preferred embodiments, the specific reaction pairs are enzyme/substrate pairs, preferably urease/urea and yeast/triacetin.

Abstract: A steam sterilization indicator for indicating both exposure to steam and sterilization is provided. The steam sterilization indicator includes a backing member. A tablet formed of a compound having a first melting point and second melting point which is lower that the first melting point, the second melting point being the melting point of the compound exposed to steam is also provided. A wick is affixed to the backing member adjacent to the tablet. A steam permeable material covers the tablet and the wick. Upon melting, the tablet material is absorbed by the wick. A handle is affixed to the backing member. One end of the handle includes a steam exposure indicator formed of a color changing ink which changes color in the presence of steam.

Abstract: A method of making and using a liquid crystal cumulative dosimeter container including a resilient outer body sealed to confine a first liquid crystal composition constituent and a second liquid crystal composition constituent and having at least one transparent section to permit observation of the color of the confined composition, and a barrier contained completely within and physically unattached to the outer body for separating the first constituent from the second constituent, whereby disruption of the barrier allows the first constituent to mix with the seocnd constituent. The barrier is formed either by encapsulating one or both of the constituents or by using air bubbles.

Abstract: This device comprises a casing of synthetic material containing a motor element made of at least one alloy which memorizes its shape and having associated with it a movement transmission element consisting of a piston and a rod and acting on at least one indicator element irreversibly recording each overstepping of a predetermined temperature, the casing being provided with transparent windows permitting the state of the indicator element or elements to be viewed.

Abstract: A steam sterilization indicator for indicating both exposure to steam and sterilization is provided. The steam sterilization indicator includes a backing member. A tablet formed of a compound having a first melting point and second melting point which is lower that the first melting point, the second melting point being the melting point of the compound exposed to steam is also provided. A wick is affixed to the backing member adjacent to the tablet. A steam permeable material covers the tablet and the wick. Upon melting, the tablet material is absorbed by the wick. A handle is affixed to the backing member. One end of the handle includes a steam exposure indicator formed of a color changing ink which changes color in the presence of steam.