I too am interested in coating methods at the moment as i am attempting to coat some 20"x24" prints in Cyanotype 2 with a glass rod. I have had to commission such a large rod to be made, B&S will make any size rod you want for $44, which is good value IMO. I am able to get two passes down on smaller prints that are 20x16" but to get the denisty i am after i think it will require 4 passes, so i plan to have to 2 syringes, once i have done the two passes and the sensitiser runs out apply another line of sensitiser and attempt another two passes.
Kenro Izu i know uses a brush to coat his large platinum prints see video below, however i just have never been able to coat consistently with a brush which is disappointing but i am sure it just takes practice as is the case with most alt photo techniques. I have used a rod for about 5 years now and don't want to put it down!
Another alternative is to use the brush and and rod as is shown by platinum printer Arkady Lvov, see video @ http://www.youtube.com/watch?v=gprrYmUCgzw
This is the best of both worlds and is a technique worth investigating.The rod enables you to get a good first coat down and then by using the brush you can even the coat out. I have tried this method and it works but again practice is key!
I will post some pictures of my progress with large Cyanotypes in the next week. I will try to blog a lot more over the coming months :)