Oxide question

Using various (cone 04-6) clays and clear gloss glaze. Am trying to add
color with different oxides.  Example is 50% red copper oxide and 50% ball
clay.  Am hoping to get a nice run with the color.  So far it's not running.
Have a thought by adding borax would help.  Am I on the right track or way
off?  Am firing at cone 04.  Any help is appreciated.

Also would I apply my color first, after the first coat of clear, or after
the last coat of clear.

Thanks in advance