Never heard of the stuff that you paint on. I have just finished doing basically what Darryl did. Hired a 1500 psi electric gurney from Coates Hire – $80 per day or weekend. The unit was too big to take on the roof but it could sit on the ground so long as you have about 20 metres of pressure hose to work with. Took about five to six hours to do the entire roof ensuring that you hose downwards away from the overlap and capping. I’m in Perth with some water restrictions but the unit did not appear to use an excessive amount of water. Make sure you clean the gutters first and they will need a light flushing afterwards. Did it on a perfect day, mostly cloudy with occasional sunshine, about 22* and the tiles were drying out behind me after about half an hour.