Autoclave tape is an adhesive tape

Adhesive tape

Adhesive tape is one of many varieties of backing materials coated with an adhesive. Several types of adhesives can be used.-Types:Pressure sensitive tape...

 used in autoclaving

Autoclave

An autoclave is an instrument used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C for around 15–20 minutes depending on the size of the load and the contents. It was invented by Charles Chamberland in 1879, although a precursor known as the...

 (heating under high pressure with steam to sterilise) to indicate whether a specific temperature has been reached. Autoclave tape works by changing color after exposure to temperatures commonly used in sterilization processes, typically 121°C in a steam autoclave.

Small strips of the tape are applied to the items before they are placed into the autoclave. The tape is similar to masking tape

Masking tape

Masking tape is a type of pressure sensitive tape made of a thin and easy-to-tear paper, and an easily released pressure sensitive adhesive. It is available in a variety of widths. It is used mainly in painting, to mask off areas that should not be painted...

 but slightly more adhesive, to allow it to adhere under the hot, moist conditions of the autoclave. One such tape has diagonal markings containing an ink which changes colour (usually beige

Beige

Beige may be described as an off tan color or an extremely pale brown color.The term originates from beige cloth, a cotton fabric left undyed in its natural color...

 to black

Black

Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light...

) upon heating. One such ink contains 30.1% lead thiosulfate, 0.6% magnesium carbonate

Magnesium carbonate

Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Several hydrated and basic forms of magnesium carbonate also exist as minerals...

, 20.1% neocryl B814, 30.1% ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

, 22.7% ethyl acetate

Ethyl acetate

Ethyl acetate is the organic compound with the formula CH3COOCH2CH3. This colorless liquid has a characteristic sweet smell and is used in glues, nail polish removers, and cigarettes...

and 49% ink solids.

It is important to note that the presence of autoclave tape that has changed color on an item does not ensure that the product is sterile, as the tape will change color upon exposure only... for steam sterilization to occur, the entire item must completely reach and maintain 121°C for 15-20 minutes with proper steam exposure to ensure sterilization.