All specimens that leave the lab have to have loan labels. We don't send out original labels with specimens- too much can go wrong. What we do instead is use a double-label technique that is automatically generated in Specify. These labels are tied to a query that will make one label with all the important information for the researcher, and another label with all the information that anyone looking in the drawer for that specimen will want to know.
Again, just click the OnLoanLabel option from the Labels section of the Reports tab. It takes a bit for the query window to pop up, but that's normal. Set the role to borrower (or, if a student is borrowing the specimens, set it to Sponsor). Enter the loan number in the correct field and hit OK. Once the labels are generated, print the print icon in the upper left. DO NOT print on both sides of the paper.