Magnetic developer is a

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shea ...

which makes the

magnetic Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...

information written on

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use mag ...

or the

magnetic stripe The term digital card can refer to a physical item, such as a memory card on a camera, or, increasingly since 2017, to the digital content hosted as a virtual card or cloud card, as a digital virtual representation of a physical card. They share ...

of a

credit card A credit card is a payment card issued to users (cardholders) to enable the cardholder to pay a merchant for goods and services based on the cardholder's accrued debt (i.e., promise to the card issuer to pay them for the amounts plus the o ...

ATM card An ATM card is a payment card or dedicated payment card issued by a financial institution (i.e. a bank) which enables a customer to access their financial accounts via its and others' automated teller machines (ATMs) and to make approved point ...

visible to the naked eye. Magnetic developer can be found in liquid or aerosol form. When applied to a magnetic stripe, suspended metal particles will be attracted to the magnetically charged regions of the stripe as the liquid evaporates. Magnetic developer can be used to troubleshoot problems with magnetic stripes and the equipment that encodes and reads them. By making the encoding visible, one can see how encoding head alignment affects the position of the data tracks, and observe any possible magnetic damage that has occurred on the magnetic stripe.

See also