I sometimes put a grooming product called silk spirits (adds shine)
my dogs - am i allowed to at Crufts? Schedule on pg 142 says:

http://www.fossedata.co.uk/downloads/flip/CRUFT_MAR_12_Schedule/#/142/zoomed

Rules are that nothing is to remain in the coat when exhibited, so a polish with a piece of silk is your safest bet.

I don't put anything on my dogs coats before showing, they may or may not get a bath before the show.

I take a pack of think hypoallergenic scent free baby wipes to polish off any dirt from the light bits.