Chipquik sells a tack flux as part of their rework product line -- you might want to try using it as the additive to decrease the viscosity of your paste.
Haven't used it myself, but it's obviously thicker than standard flux from the videos of its use that I've seen.
http://www.chipquikinc.com/store/flux.htm-e
--- In Homebrew_PCBs@yahoogroups.com, "Boman33" <boman33@...> wrote:
>
> Hi Tom,
>
> I already did that but adding 50 % liquid flux to the solder paste I get a very liquid runny mixture that does not stay on the pads. I am hoping to find paste flux and mix it with the solder paste.