I have a question about solder paste. When the solder paste lost her tackines (dry out) how can i refresh this solder paste?. Can i add a little flux? or it is ban. I noticed that after reflow solder joints look shiny but i can see some discolour (for example blue color etc). Max reflow temp 220C.
Depends on the manufacturer but I know with Kester they strictly tell you once paste dries out it can never be brought back to usefulness. Adding flux will alter the properties of the paste and may affect the final product.