Adalimbi

Hi, I can't find any info in the rules as to how many cloths are needed for UDX scent discrimination and can you really have any colour? Also, for both UD and UDX, how many sets will I need if I am doing heaps of trials close together? And, how long does it take for the scent to dissipate off of the articles? Any tips for teaching these would help too :o) Thanks.