The interpolation split

Ray Larabie

Back in ancient times, I used the FontLab's* blend tool to create a weight range. I'd start with one blend, usually 50%, which I'd clean up before making intermediate blends. The blend tool left a mess of crazy-ass beziers to clean up but it gave me a chance to fine tune the medium† weight. I could diminish some of the optical tricks, fix the balance on my diagonals, fatten up the punctuation and get my medium weight looking just right. After that, I'd blend the intermediate weights without much visual adjustment; just cleaning bezier disasters. When I was designing the heavy weight, I could do all the optical tricks I felt like without a care in the damn world because I knew I could fix the medium weight later.

For the last few years, I've been multiple mastering but lately I found that I want to start toying with that medium weight again. And I'd like to go a little crazier with the heavy weight without ruining the medium weight.

What kind of workflow can I use? Do I add the medium weight as another axis? Whaddoido?


* I use Windows so I can't use a lot of the fancy interpolation tools available on other platforms

† not necessarily medium but something around the middle

Chris Lozos

Ray, I work somewhat like you describe.  I make several interim masters.  I rarely use any master for more than one weight to either side.  The lighter weights are easy but when you get to the bolder ones you need a lot of handy work and more contrast to fight with all the demons.  Lately, I have abandoned MM and gone to the Blend tool.  I get fewer screwy bezier screw-ups that way but there is still some voodoo involved.

Ray Larabie

You end up with two masters? light-medium and medium to heavy. But then all changes to medium need to be duplicated in both masters, no?

Jameson R Spires

I have been working on a project which would require this due to the heaviness of the heavy weight.
My thoughts were to either set up separate glyphs for those that are going to end up looking different at the extra heavy end of the spectrum, or set up an additional axis with the same weight but differently shaped master in two places.
Using separate glyphs, you would set up one version to interpolate for the low end and one version to interpolate for the heavy end.
For the second method, using Wt and Op axes for example (axis names being arbitrary), the light could be at Wt0 Op0, the medium masters at Wt1 Op0 and Wt0 Op0, and the heavy at Wt1 Op1. In this case, keeping the optical size at 0 or 1000, would be the switch and the weight could be varied in between.
The first method would definitely work, and in theory, the second should as well. Keeping them all in the same MM file would avoid interpolation errors.

Christian Thalmann

Not sure if this translates to FontLab, but in my current Glyphs project, I only have full masters for Hairline and Bold. Whenever I do optical corrections in the Bold that will look excessive in the interpolation, I insert a third master at Medium weight for that glyph only using the brace trick. Example:

Two masters. The /n's shoulder thins too much at light weights.

Third master for /n inserted at Medium:

Vassil Kateliev

I agree with @Jameson R Spires. His second proposition - medium on another axis is the way to go here. It is cleaner and takes advantage of the inbuilt MM functionality + workflow comfort. I have tried it some time ago and it was bit confusing, cause you work on a quad master but use only three, but worked very well. I seem to remember that there was a rather large article on typophile.com (regretfully down).

Chris Lozos

Ray, in my case, the instance becomes the master so it brings the changes with it.