From Warhammer Tournament Rules....
"No one likes playing against an army consisting of unpainted, inappropriately
based or broken and chipped models; this is a grown up hobby played by grown up
people who are sensible enough to know both what “fully painted” and
“acceptable” means. Unpainted miniatures are not allowed, and as such will be removed from play by Referees. Additionally, any conversions or scratch-built models that are considered to be unsuitable by the Referees will be removed from play.
Bare undercoat never counts as painted, and just sand on a base is not enough; the list of what makes an unacceptable army is extensive, but suffice to say if you’re not sure, ask before the day of the event with enough time to make any changes that you need to make.
Painting covers all styles, from inking to washes and dip, to highlighting and shading. Since there are so many techniques available for the painter, the Referees will do their best to be open minded about the techniques used, but in the end, it is all about aesthetics and the Referees' call.
We wholeheartedly encourage players to go to town with their armies and bring along interesting and innovatively converted or scratch built models that represent both their skills and their love of the hobby and its background." - Games Workshop