Paper Weight

The notebook is the object in a carry system that gets the most daily use and the least visible design effort. Most notebooks are conceived around what they look like closed rather than what they feel like in use, which is where you spend all the time. The Interface Notebook starts from the other end of that sequence.

Choosing a Paper Weight

The paper decision comes first because it determines everything downstream. We use an uncoated wood-free paper at the heavier end of what carry notebooks typically run, and the reason is show-through. At the weight we chose, ink from a medium-weight pen sits on the surface without significant migration to the reverse side. Most comparable notebooks land a step lighter, where show-through becomes a practical consideration rather than an aesthetic one. The extra weight removes a constraint on how the notebook gets used without adding meaningful bulk to what you carry.

The surface finish matters as much as the weight. An uncoated sheet resists smearing and accepts both ballpoint and gel ink without the pooling you get on lightly coated papers. Leuchtturm1917 built their reputation partly on their dot grid layout, but the paper itself has always been a compromise, and their community has spent years working out which pens perform and which don't. We started from the opposite direction, choosing the paper first and designing the rest of the object around it.

What the Cover Does

A rigid cover does one thing that a soft cover can't, which is let you write without a desk. The Interface Notebook is meant to be used in the hand, on a knee, standing at a counter, and the cover has to hold its structure across all of those positions. Leather is the conventional premium signal in this category, but it responds to moisture unpredictably and develops surface variation through use in ways that affect the cover's structural performance over time. We chose a material that holds its shape at the corners through extended use, performs consistently in daily contact with other objects in a bag, and sits correctly against the rest of the carry system.

The Elastic Closure

The elastic runs around the exterior of the cover as a loop rather than a strap, which means there's nothing to tuck and nothing to catch on the way out of a bag. The main alternative is a strap closure or a magnetic flap, both of which create a deliberate pause between picking up the notebook and writing in it. The loop removes that pause. The time between reaching for the Interface Notebook and having it open to a blank page is one motion, and that turns out to matter more in daily use than it sounds like it would.

The Size Decision

A5 is not a creative decision, it is a constraint that has been tested enough times to be trusted. It sits in a jacket pocket with some effort and a bag pocket without any. B5 gives more page but requires a larger bag. Pocket notebooks give portability but constrain what you can put on a page. We chose A5 for the same reason most designers do, and then spent the time on the decisions that aren't already resolved: the paper, the cover, and the closure, and how those three things hold together as a single object worth carrying every day.