I was talking to Jesus on live support, and we got talking about my solder wetting out issue - and I jokingly said:
"I wonder if using some silvo or something on the board after baking would help? lol
remove the oxide from the silver particles?"
So I went and grabbed a bottle I had seen on a coworkers desk yesterday and tried it.
The masking tape is so I can get a better A/B line for photos. The tape didnt quite stick with the solvent in the Silvo attacking it as I polished (10-15 seconds of polishing, same again buffing with just paper towel.)
The results are fantastic, the silver is basically mirror finish (white in the picture below, as it reflects the white softbox providing light. I'm showing the board rotated 180 degrees to show that it is not just a trick of the light.
Now how does it affect soldering you might ask?
On the left, was covered by masking tape. On the right is polished. The lower right one was my first try, where I soldered it more like I was last night. The top ones are about 2 seconds each, with a chisel tip at 210*c on the pad, feeding wire in. The pad on the right wet out almost like copper, the pad on the left.. well... it didn't wet out.