A method of producing a stent-balloon assembly is disclosed which includes providing a stent having a polymeric component; exposing the stent to a relative humidity of 20% to 100%; and crimping the stent on a balloon of a catheter assembly. The polymeric component could be at least part of the material from which the stent is made or could be a constituent of a coating for the stent, such as a drug delivery coating. In lieu of or in addition to the application of humidity, a plasticizing agent can be applied to the polymeric component. A crimping device is also disclosed which allows the stent to be exposed to humidity during the crimping process.