Gum over platinum has a different look than pure gum. Plus, pt/pd printing is quite economical, despite rumors to the contrary. If you take into account the labor to produce a 1 or 2 layer gum over pt/pd compared to a mutilple coat gum (say 3 or more layers - some gum printers use many coats), gum over platinum is cheaper if you place any value on your time. Below is an example of the same negative printed as gumover pt/pd and 100% multi-coat gum.
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