The Professional Font Engineering Process: From Design to Deployment
As a professional Font Engineer who has helped bring over 400 font families to life, I’ve refined a systematic approach to transform design concepts into functioning, high-quality fonts. This article presents my complete font engineering workflow, from receiving initial designs to final deployment.
Phase 1: Design Assessment and Planning
Initial Design Review
When I receive design files from a type designer or client, my first step is a thorough assessment:
- Format Evaluation: Are the designs in suitable formats (UFO, Glyphs, FontLab, etc.)?
- Design Completeness: Is the character set complete for the intended language support?
- Technical Feasibility: Are there any design elements that might pose engineering challenges?
- Interpolation Potential: For variable fonts, will the masters interpolate cleanly?
Technical Specification Development
Based on the initial assessment, I create a detailed technical specification that includes:
- Character set mapping: Defining the full Unicode coverage
- OpenType feature requirements: Identifying necessary features like ligatures, alternates, contextual substitutions
- Interpolation strategy: For multiple weights or variable fonts, defining masters and axis ranges
- Output formats: Determining which font formats will be required (OTF, TTF, WOFF2, variable fonts)
- Technical constraints: Noting any platform-specific requirements or limitations
Phase 2: Outline Engineering
Outline Consistency
The core of font engineering begins with ensuring outline consistency:
Point Structure Optimization:
- Minimizing point count for efficiency while maintaining design fidelity
- Ensuring consistent point placement (extrema points, handle alignment)
- Converting all curves to TrueType or PostScript format as appropriate
Component Assembly:
- Identifying repeatable components (such as diacritical marks)
- Implementing component references for consistent design and reduced file size
- Verifying component alignment and behavior
# Example of Python script I use to check extrema points
import fontParts.world as fp
font = fp.OpenFont("path/to/font.ufo")
problems = []
for glyph in font:
for contour in glyph:
for segment in contour:
if segment.type == "curve":
# Check if point at extrema
if not segment.hasExtrema():
problems.append(f"{glyph.name}: Missing extrema point")
print(f"Found {len(problems)} issues")
for p in problems:
print(p)
Metrics and Kerning
Establishing consistent metrics is crucial for font performance:
Vertical Metrics:
- Setting UPM (units per em), typically 1000 for PostScript or 2048 for TrueType
- Defining consistent ascenders, descenders, and line gaps
- Ensuring cross-platform compatibility of vertical metrics
Horizontal Metrics:
- Setting sidebearings with mathematical consistency
- Reviewing and refining auto-spacing results
- Implementing class-based kerning where appropriate
Kerning Optimization:
- Reviewing and refining auto-kerning results
- Implementing class-based kerning for efficiency
- Ensuring kerning consistency across weights
Phase 3: OpenType Feature Implementation
The power of modern fonts lies in their OpenType features:
Feature Planning and Implementation
Basic Features:
- Standard ligatures (liga)
- Localized forms (locl)
- Stylistic alternates (salt)
- Proportional/Tabular figures (pnum, tnum)
Script-Specific Features:
- For complex scripts like Arabic or Indic scripts
- Mark positioning (mark, mkmk)
- Contextual alternates (calt)
- Required substitutions for proper rendering
Advanced Typography:
- Stylistic sets (ss01-ss20)
- Contextual swashes (cswh)
- Historical forms (hist)
- Small caps (smcp)
Here’s an example of OpenType feature code I might implement for a font with stylistic alternates:
# Stylistic Set 1 - Alternate lowercase 'a'
feature ss01 {
featureNames {
name "Alternate a";
};
sub a by a.alt;
} ss01;
# Contextual swash for end-of-word positions
feature cswh {
lookup END_SWASH {
sub [a e i o u] [@Punctuation space] by [a.swsh e.swsh i.swsh o.swsh u.swsh];
} END_SWASH;
} cswh;
Phase 4: Interpolation and Variable Font Setup
For multi-weight families or variable fonts:
Interpolation Preparation
Compatibility Checking:
- Ensuring matching point counts and structures across masters
- Verifying component composition consistency
- Correcting incompatible outlines
Master Positioning:
- Optimizing master positions along design axes
- Adding intermediate masters for non-linear interpolation if needed
- Testing interpolation results at various instances
Variable Font Specific Work
Axis Setup:
- Configuring standard axes (weight, width, slant, etc.)
- Setting up custom axes when required
- Defining axis ranges and default values
Named Instances:
- Defining named instances for common weight/style combinations
- Setting appropriate STAT table entries
- Testing instance rendering
Optimization:
- Implementing delta hints for better interpolation
- Optimizing for file size
- Ensuring the variable font performs well across its design space
Phase 5: Hinting and Rendering Optimization
Even with high-resolution displays becoming more common, hinting remains important for cross-platform consistency:
TrueType Hinting
For fonts that will be distributed in TTF format:
Basic Stem Hint Programming:
- Identifying and setting up standard stems
- Programming alignment zones
- Implementing basic hinting instructions
Advanced Hinting:
- Pixel-level control for small sizes
- Delta instructions for problematic glyphs
- Fine-tuning at specific point sizes
PostScript Hinting
For fonts that will be distributed in OTF (CFF) format:
Hint Programming:
- Setting up horizontal and vertical stems
- Defining alignment zones
- Implementing hint replacement for complex shapes
Blue Zones:
- Setting up proper baseline and x-height zones
- Configuring overshoot values
- Fine-tuning for optimal rendering across platforms
Phase 6: Compilation and Testing
Font Compilation
Converting the engineered font files into final formats:
OTF/TTF Generation:
- Compiling static fonts from source files
- Setting appropriate metadata (name table, OS/2 table)
- Optimizing for performance and size
Web Font Generation:
- Creating WOFF and WOFF2 versions
- Subsetting when appropriate for web performance
- Testing compression efficiency
Variable Font Packaging:
- Generating variable font files
- Implementing subsets for web use
- Ensuring all instances work as expected
Comprehensive Testing
Rigorous quality assurance before delivery:
Technical Validation:
- Using tools like FontValidator, TTX, and FontBakery
- Checking for outline errors, table issues, or inconsistencies
- Validating OpenType features function correctly
Cross-Platform Testing:
- Testing on Windows, macOS, iOS, and Android
- Verifying browser rendering in Chrome, Firefox, Safari, and Edge
- Checking appearance in common applications (Word, Photoshop, InDesign)
Performance Testing:
- Evaluating font rendering at different sizes
- Measuring loading time for web fonts
- Testing variable font performance across the design space
Phase 7: Delivery and Documentation
Font Packaging
Preparing the final deliverables:
File Organization:
- Organizing files by format (OTF, TTF, WOFF, WOFF2)
- Creating appropriate variable font packages
- Including source files if specified in the agreement
Metadata Verification:
- Checking all metadata is correct (copyright, version, etc.)
- Ensuring proper naming across all font files
- Verifying license information is included
Documentation
Creating supporting materials:
Technical Documentation:
- Listing included features and how to access them
- Providing implementation guidance
- Including any known limitations or compatibility notes
Designer’s Guide:
- Creating specimen PDFs
- Documenting available OpenType features
- Providing usage examples and best practices
Implementation Support:
- CSS examples for web implementation
- Application-specific guidance
- Troubleshooting information
Case Study: Engineering a Corporate Variable Font
To illustrate this process, here’s a brief overview of how I applied this workflow to a recent corporate variable font project:
Client Requirements
A global corporation needed a custom variable font that:
- Supported Latin, Greek, and Cyrillic scripts
- Needed to work across all their digital platforms
- Required excellent legibility at small sizes
- Needed to maintain design consistency across the weight range
Engineering Approach
Assessment Phase:
- Identified potential interpolation issues in curved terminals
- Recommended additional masters for optical sizes
- Suggested technical specifications for cross-platform compatibility
Engineering Implementation:
- Optimized outlines for variable font interpolation
- Implemented comprehensive OpenType features including localized forms
- Created custom axis for optical size adjustments
- Developed desktop, web, and app-specific versions
Results:
- Final variable font reduced web font payload by 68%
- Perfect rendering across all required platforms
- Improved legibility at small sizes through optical size axis
- Seamless weight interpolation with no visible artifacts
Conclusion
Professional font engineering requires technical expertise, systematic processes, and meticulous attention to detail. Each phase builds upon the previous one to transform design concepts into high-quality, functional fonts that perform consistently across devices and platforms.
As font technology continues to evolve, the engineering process becomes increasingly sophisticated. Variable fonts, color fonts, and new OpenType capabilities provide exciting opportunities while also introducing new technical challenges.
If you’re a designer looking for font engineering services or a company considering custom font development, understanding this process can help you better prepare your projects and collaborate effectively with font engineering specialists.
Rahul Gajjar is a professional Font Engineer with expertise in developing high-performance fonts for global brands. With experience engineering over 400 font families, including complex script fonts and variable fonts, he provides technical expertise to bring typographic designs to life.