Metallics can be difficult regardless of the ink manufacturer. Adding "Water Resistant Compound" is a raw materiel that your ink supplier should be able to furnish you. This ingredient helps in both bodying up the ink and fighting off over emulsification for occuring. Remember, metallics have very little vehicle but a good slug of colorant.
Running your Mitsubish, you can always kick up the Delta - predamp speeds, kick up the fount and reduce the sub, and if in a real pinch - get some of the "Magic Purple Juice" that all of the manufacturers have that is to be added to the mixed fountain solution. Ours is Called "Fount Additive" and is loaded with desensitizers that aid in keeping fine screens or reverses open when running metallics. It forces the non-image area to become water receptive.
If you're desperate, remove the ink from the plate surface using your wash. Then clean the image area using Coca Cola ( Not Diet =) ). The acids in the soda will work as a fantastic desensitizer.
Good luck.
Best Regards,
Aaron Sures
Gracol 7 Expert