Commercial mini-lab RA-4 chemistry sets seem to cost a fraction of the ambient temperature monochemicals.. some of the RA-4 minilab sets even appear to be more environmentally sound and safer, to provide better capacity etc. Cheaper. Better. All sounds great.. except that the stuff comes in concentrates for for at least 10 liters.. if not 2x10l or even 4x10l.. 10 liters is a lot... 20 liters is twice a lot.. The questions then are: - How long can one (dividing into smaller bottles) store the concentrates? - How long can one store the virgin bottles of concentrates?