Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Definitely, brake fluid is not necessary. If your board is clean ink sticks good enough. I am only using it while printing on the other side of 2 layer pcb since board start to oxidize while drying step of first side. If you use brake fluid be sure that it is very very thin and ink settings of the printer is at minimum otherwise ink will start to cover whole board. As Stefan says, 3-colors are only required if you are not sure about the status of the nozzles. I am lazy enough to do nozzle test each time so this is my approach. As an ink mixture I am using 90% yellow+10%magenta MIS inks in all cartridges except black. The black cartridge is filled with only water in my printer.

Volkan
.....not use the brake fluid all the time, it is not necessarily needed.