Standard 25 ICSB 40-029 e 01/98 4-34 CARE, MAINTENANCE AND TROUBLESHOOTING4.1 Care and maintenance of the instrumentMaintenance of the Standard 25 ICS is limited to the following operations: Cover the instrument with the dust cover after every use. Do not set up the instrument in a damp room, i.e. max. humidity 85%. Remove dust from optical surfaces using a rubber blower or a natural hair brush. Use alcohol toremove grease from brush, then dry the brush. Remove stubborn dirt and fingerprints using a dust-free cloth or leather cloth. Remove stubborn dirt (e.g. fingerprints) from optical surfaces using commercially available opticscleaning cloths; if necessary, slightly moisten the cloths with petroleum ether.Clean the front lenses of the objectives using petroleum ether, but do not use alcohol.When using the Standard 25 ICS in humid climatic zones, proceed as follows: Store the Standard 25 ICS in bright, dry and well ventilated rooms with a humidity of less than 85%;store particularly sensitive components and accessories, such as objectives and eyepieces, in a drycloset. When the equipment is stored in closed cases for a longer period of time, the growth of fungus canbe avoided by including cloths soaked in fungicide in the cases.The risk of growth of fungus on opto-mechanical instruments always exists in the following conditions: relative humidity of more than 75% and temperatures between +15° C and +35° C for more thanthree days. installation in dark rooms without air ventilation, and dust deposits and fingerprints on optical surfaces.