Getting my horse used to spray? ?

How can I get my horse used to the spray bottle? I can't put fly repellent on him and I can't put a coat shiner on him for shows! He also hates me spraying his cribbing solution on the sides when his stables.. At the moment I can spray it on the sponge right next to him and he doesn't care so it's not the smell or the sound, it's just the feeling of it on him! Any ideas? As in the summer I will have to spray 30 horses then turn them out so I can't waste time spraying it on a sponge! Also it uses more of it up so its more expensive!