No problem at all. Storm Apparel Proofer is a heat cure solution, this means you need to add a form of heat in order to activate the DWR performance. This emulates the way your garment will have been made at the point of production. To activate your DWR without a drier, simply go through the normal easy care one wash cycle, leave your jacket to air dry and then check your garments care label, if its safe to do so iron your garment on a low temperature setting as per your care instruction label, making sure to add a clean, damp cloth between your outer textile and the iron itself. If you have no iron or drier, simply hang your garment close to your radiator and rotate your garment from time to time to make sure all exterior faces of the garment have been directly exposed to the radiator heat.