Homebrew PCBs

> How much are you thinning the solder paste before you paint it on? It 
> sounds like you're really thinning it down quite a bit.

The reason for thinning is not to prevent solder forming where there is 
no copper. You thin to get an even layer of paste without ridges or 
brush marks that will cause some places to have too much solder. Areas 
without copper will be filled with tiny discrete balls of solder that 
wash off quite easily.

A new jar of paste may be so moist that no thinning at all is required. 
Whatever, thinning will usually consist of just adding a few drops of 
water at the top of the paste in the jar or wetting the brush 
occasionally. Sort of like painting with solid water paints.

I don't have many pictures of the process but here is a shot of what to 
expect if too much paste is used....Raised rings around would be holes 
in pads and raised tracks and pads (some may prefer this);

http://www.pbase.com/eldata/image/47810059/original

Caution:
Depending on paste used, it may contain lead and/or an acidic flux.