The Digital Hygrometer is a must for all eyelash professionals. With the hygrometer you measure the humidity and temperature in the room. Room temperature and humidity determine the drying time of the eyelash glue. The higher the humidity, the faster the eyelash glue usually dries. Here it depends on the properties of the glue. Recommended is a temperature between 18-23 ° and a humidity on average between 40-70%.