Pigment/gum ratios
There was a recent thread that I missed out on because I was preoccupied with a different project, that had to do with whether people pre-mix their gum and pigment and if so, how they pre-mix their gum and pigment. I didn't have time to read the whole thread, but I did notice that Judy said she doesn't premix pigment with gum. I do; I work from a stock mix of pigment/gum. But I don't mix a standard amount of pigment into a standard amount of gum as some do, because I can't think of a reason why that makes sense. Since pigments vary widely in pigment strength, and since even for the same pigment, brands vary widely in pigment strength, it doesn't make sense to me to use an arbitrary pigment/gum ratio. If you do that, you'll end up with mixes that vary widely in color saturation and in whether they are properly pigmented or not. If you use the same amount of pigment per gum for lamp black as you do for burnt umber, for example, either the lamp black is going to be way overpigmented, or the burnt umber is going to be way undersaturated. I prefer to standardize on color saturation, which means using a different amount of pigment per gum depending on the pigment and the brand, and mixing to a color swatch that gives the optimal printing concentration for a given pigment/brand. Then I use that stock mix in various ways, depending on what I'm doing. For a one-coat gum, I'll use the stock mix straight. For a multiple gum, I'll most often use a diluted mix, because while in a one-coat gum you want the greatest DMax that a pigment is capable of, in multiple gums, and especially in tricolor, to use each pigment at the maximum color saturation would result in poor tonal balance (too dark) and probably poor color balance as well, because pthalo especially needs to be backed way down to balance against the other two colors. And I will adjust the mix to achieve different aesthetic goals; for example, for the very high-key work I was doing 2001-2004, I added a huge amount of gum to the mix (like 1:10) to achieve very pale, almost invisible, colors. And I often mix the mixes to create different colors, as well. Katharine
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