• design
  • hardware

At FiftyThree we are obsessed with tools: simple tools that empower their users to do their best work. Take the Hori-Hori for instance, a well-loved Japanese garden knife that combines simplicity with thoughtful functionality. Its curved, partially serrated blade emboldens the “Zen Gardener” to clear weeds, carve out planting holes, and split perennials all in one go. Tools like these earn their love out of sheer usefulness and often we ask ourselves how we can bring the same graceful utilitarianism to tomorrow’s electronic tools.

A Stylus Fit For Goldilocks

From the beginning of FiftyThree, we have used and evaluated a long list of digital stylus products for iPad. What we noticed from testing these tools was that they competed fiercely over four main features: tip feel, size, durability, and pressure sensitivity. Surprisingly, all overlooked one key attribute found in analog writing tools — Surface Pressure. We define this phenomenon as the ability to vary stroke size according to how much of the tip surface area is pressed against the writing surface.

Charcoal: “expressive” from every side, edge, and angle.

From Kindergarten we intuitively turn our crayons sideways to shade, or shape a kneaded eraser to achieve a desired erase width. Think: Bob Ross + fan brush + surface pressure. What Bob Ross achieved while wielding one brush—one tool—impresses us still: small taps of the brush tip corner created branches of evergreen trees while light, circular motions with the same brush formed fluffy tops of cumulus clouds. Surface Pressure, then, is the culmination when physical form and digital expression work together. The dynamic interaction between the two creates strokes of varied widths in a simple and natural way that’s hard to achieve when you’re bound to a brush size menu and “stupid stick.”

A Digital Crutch

Today, most styli and drawing apps compensate for surface pressure limitations by integrating settings and menus to vary stroke size. But imagine stopping to grab a different lead pencil every time you wanted to switch from shading to creating fine lines. It would disrupt the creative process and take you out of the flow. However, the few digital styli that vary stroke size based only on pressure also miss the point. To us, it just doesn’t feel right. So we set out to create an application and physical writing tool that dynamically respond to each other as you would expect in the analog world, Paper and Pencil.

Making The Most of Surface Pressure

Pencil’s core design is built around the idea of Surface Pressure and we’re excited to unlock Pencil’s full potential on iOS 8. But how does it work exactly? For Pencil, Surface Pressure is a function of its tip and eraser design. Both provide the user a wide range of stroke sizes which are determined by how much tip or eraser surface area comes in contact with the screen. The tip and eraser geometry are dynamically linked to our expressive ink behavior as shown below.

  • Pencil Tip. The tip geometry blends from a spherical cone to a larger rectangular shape for a wide range of stroke possibilities, enabling the user to draw thin strokes at steep angles as you would expect. As Pencil’s broad tip glides across the screen, wide and expressive strokes are rendered.
  • Pencil Eraser. The eraser geometry is rectangular with rounded corners. When erasing at an angle you can remove finer details. Rotate the eraser to the wide edge and Pencil creates a larger contact surface area which produces a much larger eraser stroke.
  • Material Play. One interesting note is that the rubber tip and eraser material is engineered to crush in a way that not only allows a great surface feel but more subtle edge control. For some inks this could mean the harder you press the larger the stroke size, like a felt tip marker.
  • The Proof is in the Pudding. It all comes together in the software. We calculate the surface area of Pencil’s tip or eraser that is physically touching the screen surface. The surface contact area is translated into an appropriate stroke size for the ink in play. The magic is in how we interpolate between varying surface contact area readings when drawing continuously at different angles. The outcome is a beautiful thick-to-thin line.

Where Form Meets Function

For the Hori-Hori, ergonomics, usage scenarios, and functionality are intrinsically woven. When carving a hole, you grip the Hori-Hori like an ice cream scooper; when cutting, you hold it like a knife. The handle was designed to accommodate varying grip positions, ensuring a secure and comfortable hold for any given task.

Paper creator Brad Ovenell-Carter showing Graphite Pencil and his carpenter pencil side by side.

Like the Hori-Hori, Pencil’s carpenter pencil-inspired form also compliments its intended functions. When taking notes, hold it as you would any writing utensil. For shading, hold it securely sideways at a low angle. On a practical level, its low, flat profile is ideal for stowing in a pocket or snapping magnetically to your iPad Smart Cover.

Reimagining Mobile Creation

From the beginning, we looked beyond the typical scenarios for creating. We wondered: what could drawing, sketching, and writing look like in two years? In a decade? As makers and users of digital tools, we strive to simplify complex systems while maximizing functionality. But that’s just us, and we’d love to get your take on it. If you could influence the future of creativity, what tool would you make?

To learn more, check out our recent Surface Pressure announcement on FiftyThree News. To get Pencil, visit our online Store or Amazon US.