I was asked a short time ago if a fly rod could be coated with Mucilin or any other type of paste floatant. This person wanted to know if you could apply it like a wax - smear it on, wipe it off. Well, I've never heard of this being done before & I wouldn't recommend it. First off, it's not going to last nearly as long as wax will. I should think it would wear off half way through a day of fishing, if not before. Second, Floatants leave surfaces feeling really slick & that could cause problems when holding your rod while releasing a fish, etc.
I always suggest using a good carnauba wax on fly rods. Yes, the same wax you'd use on a car or a boat. Be sure to use pure carnauba wax only & avoid those that have cleaners & other chemicals added to them. Applied properly, it will give your rod good protection & enhance its beauty.. Also, try different brands of wax to find the one that works best on your rod's varnish.
By the way, Mucilin comes in two varieties these days: regular (red label), & silicone (green label). It's highly recommended that you use only the red label Mucilin on bamboo rods. The silicone in the green label stuff can react with some varnishes on some bamboo rods & damage the varnish. Besides, the red label Mucilin is the old traditional one.
So keep your floatant on your fly line (silk or synthetic) & on your dry flies where it belongs. Find a good wax to use on your fly rod, apply it properly, & years from now when your varnish is still in great shape you will be glad that you did.