i forget the exact stuff i used when i was working at NTP, but it was this solution stuff, and you drip it onto these swabs and go from there...it really helps to pick up one of the magnifying lights (forgot the name of that as well) so you can really see the sensor and where the spots are. I'll be going there probably by wednesday and if you can wait till then i'll tell ya exactly what the stuff was and how much it is...