Tape Release Agents

Before the adhesive side of tapes can be treated for fingerprints or sampled for DNA traces it will first need to be removed from the surface to which it is stuck. A number of methodes are used for this. One physical method relies on the fact that the adhesives used on tapes lose their rubber-like properties when the temperature is lowered enough. Putting the evidence in a freezer is one method that sometimes works. Locally cooling the tape with freezer spray (used in electronics) is another. For tapes on paper a tray with liquid nitrogen can be used.
On smooth surfaces removing a tape can be aided by heating the tape with a heat gun.
In the past when the adhesive-side of tape was based on cellulose ("Sellotape"), acetone and hexane were used for removing tape from paper. With modern pressure sensitive adhesive tapes more identifiable fingerprints are recovered with "Turkish solvent" or the older release agent based on a xylene substitute used in microscopy to which 5% chloroform or (less toxic) dichloromethane is added (Journal of Forensic Sciences, 1990, Vol. 35, No. 6, pp. 1373-1383; [doi:10.1520/JFS12973J]; in which a method to unravel tape stuck adhesive side to adhesive side is described).
Heptane (the ingredient of Un-Du label remover) is also used.
"Turkish solvent" was popularized in the beginning of this century by Uwe Amerkamp from the BKA who visited collegues in Ankara, Turkey and noticed the good results they got using a mixture of cyclohexane and isopropanol (1:2) as tape release agent.
The xylene subsitute is a mixture of aliphatic hydrocarbons ("hydrotreated heavy naphtha") so chemically similar to hexane and heptane although this mixture has a higher boiling point.
Product #
Turkish tape release agent, 250 ml ready-to-use
Tape release agent, 250 ml ready-to-use mixture of xylene substitute and dichloromethane