http://www.typophile.com/node/32313

Also: http://typophile.com/node/99181
To which I hope to add some elaboration soon.

hhp

Thanks for the links guys! Nonetheless I think I wasn't clear enough in explaining what I'm looking for... What I need is the way that bold strokes are extrapolated from, let's say, a light variant. Changing the stroke width in Illustrator is not enough as I've read, it may give equal widths on every stroke but typefaces hardly are so mathematically constructed as I have seen. For example, I took letter p from Myriad Regular, ran the Bold action in FL with a parameter of 40-40, and compared the outline to Myriad Black... needless to say, they are quite different! So, the designer somehow decides how every stroke will relate to the rest, keeping harmony between the shapes and the character of the letterform.

In this same subject, I believe the initial letterforms and interior spaces will dictate how much I can "fatten" a character. Maybe some of you had already seen my font Shket, it has elongated and narrow forms, and some characters like "f" have small curves. Is technically possible to make a bolder version from that letter? If so, How far could I go? Maybe an Extra Black is out of the equation.. but I don't know yet.

Those are the kind of questions I need answers to. I haven't found resources or literature dealing with this technically complex stuff.

Regards!

Best to do it all manually, but:
http://www.typophile.com/node/81774

Good news: the latest version of FL has inherited Fog's algorithm.

hhp

http://www.amazon.com/The-modification-letterforms-Stanley-Hess/dp/09101...

In practice, I design the Regular weight first, then draw Extra Bold by fattening up the Regular with various FontLab tools (some global actions, some cut and paste, whatever it takes). Then I draw the Thin as a stroked monoline (over the Regular in the mask layer). Then I interpolate the other weights between these three instances, with a final manual clean up. Some people use the Superpolator app for interpolating, rather than Blend in FontLab.

Again thank you both!

Nick: Looks like I'll be needing to buy that book. Any online resources that you are aware of dealing with the same topic? I cannot believe there's only one book dealing with the subject of letterfom modification.

I’m sure there are some more that are helpful, like Karen Cheng’s.
But the Hess book offers a profound analysis, IMHO, and he made all his own glyphs to demonstrate his theory.

There's one very nice diagram in Frutiger's "Type Sign Symbol":
http://welovetypography.com/post/2837

BTW one twist I apply to the techniques Nick kindly revealed is to dump (actually, use as a reference in the Mask) the original Regular in favor of the eventual interpolated one - although I do tweak the extremes to get an interpolated Regular as close as possible to the one I originally made. Doing so ensures that things are squeaky clean.

hhp

Yes hrant, I understand the techniques revealed by Nick... but no interpolation technique will be good if my base forms are no correct. First I need to get technically correct bold shapes, and then begin thinking about interpolation! )

Here’s a great thread on the subject, but sadly the images are gone. This place is falling apart.

I like using a tool called Interpolation Nudge: For the x-direction I lock left edges and move right edges (uncheck “adjust sidebearings” and move everything to the left half the distance you added to the stems). The tool interpolates curves and points between what you lock and what you move. For the y-direction, I lock whatever points I want to keep in place, and move the what I want to move, often over several steps. This all ensures that I take as “much” from the white as I add to the black. In the end, the bold needs the same level of attention to design as the roman, but a method like this can help you see its relationship to the roman more clearly and function as a guideline for spacing and proportions.