I am making a font family with multiple weights. I want the tracking for the lightest variant to increase. I think more space would help with readability.
Is it possible to set tracking for the lightest weight and interpolate it for exports between thin and bold? If so, how?
What do you mean by specifying metrics? The (horizontal) metrics are specified by the spacing you design. That needs to be done manually, or by automation solutions such as HT Letterspacer.
What I’m trying to say is that I would like to adjust the default tracking (for all characters) relative to the side bearings that I’ve already specified. Moreover, I’d like to have more tracking for the light variant of my font family and tighter tracking for the heavy variant. I would also like the difference in tracking to be interpolated for every export between light and bold. Can this be done?
Tracking is the spacing between glyphs applied to an entire piece of text. That is something that is applied at the user application level, not built into the font, and different applications do it different ways when they offer it at all.
Spacing is the basic spacing you built in to each character, and I am assuming that is what you want to adjust in your light weight. Since you want to do it to the entire light weight, try mekkablue’s suggestion above. That is the quickest way. The other way is to adjust each character individually.
Interpolation of the spacing for the different exports will happen proportionately after you do that.