Homebrew PCBs

I've looked at a few pastes, and they all said must be cleaned after  
soldering with damp rag.
So i reckon the flux is a no-go for SMD work. I don't consider it a  
problem for board tinning as it is soluble and you can certainly clean a  
board so it is removed (remember we etched it in pretty bad acid in the  
first place).
I don't thik however it can be washed out 100% under SMD parts.

Maybe one could put a larger amount of the stuff on SMD pads after  
painting, reflow, clean, put a drop of sticky resin flux on each SMD pad  
and position the components, reflow. But other than beeing possibly much  
cheaper there is not real advantage here.

still i'll certainly try tinning boards this way - sounds great.

ST