Hi cwatts,
Any resolution to your scumming issue ? I thought of your inquiry at a recent press cleaning.
I still think it is calcium glaze, not "ink shine". I mean that with no disrespect to the esteemed minds on this forum. Your experience and knowledge is immense and I will continue to learn much from you.
I cleaned an RMGT Series 9 LED-UV press on Saturday using a new product. The far right of the roller is what the entire roller looked like prior to the cleaning. The remainder of the roller is after the cleaning.
This photo is from the black unit. There is a distinct difference, as you can clearly see.
The calcium glaze and contamination was high even though the press is cleaned every week, because calcium is a major problem in the pressroom. No one can stop it and current offerings on the market do not clean thoroughly. They may help somewhat but truly are ineffective overall. Calcium traps everything in the rollers. It acts as a "laminate". Once the calcium was gone we released an enormous amount of ink, paper lint, gum and other roller debris. The photo of the wash-up tray shows that as well.
I think the photos are quite revealing as to what is contributing, in part, to the GTO52 print issues. There may be other problems you face, cwatts, but calcium contamination is surely one of them.