Epoxy vynilester resin /green color

Hi Group.
My company manufactures pipes and fittings in GFRP using epoxy vynilester resins (Basf, Ashland, Reichold, etc), once the resin is promoted with Cobalt octoate, its color change from clear to purple color, then when the hardener MekP is added, the resins change its color from purple to green. My question is , there is a way to get a hardened vynilester resin in clear color?, maybe changing the Cobalt with DMA?. We do need to coat some products but the green color is not accepted.