EFFECTS OF TEMPERATURE
Temperature has three basic effects on magnetic tape. It can impact the physical dimension of tape, the speed at which the binder decays and the lubricants.
Tape expands and contracts with temperature. Even though tape can be thousands of feet long and only a very small fraction of an inch thick, the primary vector of expansion is thickness. As tape gets hotter, the tape gets thicker and tightens the pack. This can cause stretching. As tape gets colder, it gets thinner and loosens the pack. This can result in tape slippage, folding and cinching.
While the primary expansion/contraction vector is thickness, temperature changes do affect the length and width of the tape. With helical scan tapes, this can cause mistracking.
The different layers of magnetic tape also expand at different rates. Frequent changes in temperature can loosen the bond between the binder layer that contains the magnetic recording and the base sufficiently to cause separation.
Elevated temperature also accelerates chemical reactions. In the presence of sufficient moisture to cause hydrolytic decay, hydrolysis will be more severe and will occur more quickly at higher temperatures.
Temperatures above 140oF will cause changes in the tape structure that are visible under an electron microscope. Temperatures above 160oF can cause tape deformation that is visible to the naked eye.
Exposure to cold also affects magnetic tapes. Below approximately 46oF, lubricants incorporated into the tape binder can crystallize and migrate to the surface of the tape. For this reason, tapes should be stored above 48o F and never frozen!
Tape expands and contracts with temperature. Even though tape can be thousands of feet long and only a very small fraction of an inch thick, the primary vector of expansion is thickness. As tape gets hotter, the tape gets thicker and tightens the pack. This can cause stretching. As tape gets colder, it gets thinner and loosens the pack. This can result in tape slippage, folding and cinching.
While the primary expansion/contraction vector is thickness, temperature changes do affect the length and width of the tape. With helical scan tapes, this can cause mistracking.
The different layers of magnetic tape also expand at different rates. Frequent changes in temperature can loosen the bond between the binder layer that contains the magnetic recording and the base sufficiently to cause separation.
Elevated temperature also accelerates chemical reactions. In the presence of sufficient moisture to cause hydrolytic decay, hydrolysis will be more severe and will occur more quickly at higher temperatures.
Temperatures above 140oF will cause changes in the tape structure that are visible under an electron microscope. Temperatures above 160oF can cause tape deformation that is visible to the naked eye.
Exposure to cold also affects magnetic tapes. Below approximately 46oF, lubricants incorporated into the tape binder can crystallize and migrate to the surface of the tape. For this reason, tapes should be stored above 48o F and never frozen!
