Elma tec clean A1 should be diluted to 3-10% with water before use. For example, a 2.5-liter bottle dilutes with water to 15 gallons of 5% solution for PCB cleaning. Tec clean A1 is formulated to be easily and thoroughly rinsed off with water, leaving no chemical residue after rinsing with distilled or deionized water. The mildly alkaline solution can be used over and over until it begins to lose effectiveness. The frequency with which you need to change the solution depends on how often you clean and the amount of contamination being removed from parts. Tec clean A1 is water-based and biodegradable; check your local regulations for disposal guidelines.