I used to use the forced air on the keyboards at the paper mill. I designed a database that the shipping department used. The one department would key in the loads and the boys on the dock take them off. Every few weeks they complained it wasn't working and I went down to blast the keyboards, find the missing keys, put them back on, and reinstall the keyboards. They had those old clunker keyboards that nothing would hurt - I could have hosed them out and they would have been fine. I have a friend who used to run his through the dish washer. Between the dust of a mill and the bad habits of the fellows, they were always a mess. The units though only got it a couple times a year unless there were problems (and yes, I used the forced air - at quite a distance and with a shop towel over the nozzle) Even at a paper mill with paper dust, dirt, and whatever semis and trains brought in we still didn't need to more often that that.