Mercury, poured not drawn
Letters that look poured rather than drawn, with a highlight down every stroke — and the pixel-and-a-half channel under the capital B that decided how the face had to be traced.
Mercury looks poured rather than drawn. Every stroke carries a highlight running its full length, and that line of light down the middle is the entire effect — it is what makes the surface read as liquid metal instead of as a fat sans with a stripe in it.
One weight, no italic, 105 characters, English only. It will not set an accented word, and there is no second weight to fall back on when the first one is wrong for the job.
Quicksilver is the word we show it in because it makes the face prove itself. The highlight has to run through a round Q, a diagonal k, a narrow s and a bare l and still read as one continuous surface, which is the hard part of drawing a face like this and the easy part to fake in a specimen of three letters.
The highlight is the thinnest thing in the face
The highlight narrows where the stroke narrows. Down a stem it has room. Under the top-left hook of the capital B it is a channel a pixel and a half wide, and that is the narrowest thing anywhere in the face.
Traced after the pipeline's default blur of 0.8, that channel closed. The two edges either side of it were nearer to each other than the blur was wide, so they averaged into one, and the top of the B came out as a slab of solid ink. Not a thin highlight — no highlight, on the letter where the reader is most likely to notice.
The rule that falls out of it is simple enough to state and easy to forget: the blur has to be finer than the finest thing the face draws. Mercury is traced at 0.3.
The Q had already been damaged
A second repair, and a different kind. Mercury's capital Q was clipped in the stored hand-prepared grid — a bad cell boundary had cut the tail off before the face ever reached the tracer. No tracing setting was going to bring it back.
It was rebuilt from the surviving cells of the original style sheet rather than redrawn. That distinction matters more than it sounds. A redrawn Q is somebody else's Q — it would have carried a different hand, a different highlight, a different idea of how the tail leaves the bowl, and it would have sat in the alphabet looking almost right, which is worse than looking wrong.
The old grids were kept. They are the record of what the face actually was, and the next time something is found to be missing, the answer will be in them or it will not be anywhere.
Where it belongs
Mercury is a display face for things that want to look like objects: album art, a drinks or cosmetics label, a film or game title card, a poster, a logotype set once and spaced by hand. It carries an obvious period reading — chrome, Y2K, the liquid lettering that came back around — and that is a reason to use it deliberately rather than a reason to pretend it is neutral.
It works for a game's title screen and for the one word on a loading card. Set large, on a flat ground, in a short string, it is convincing in a way a plain sans with a gradient on it is not, because the highlight follows the stroke rather than the bounding box.
The ground matters more here than for most faces. The highlight is not white ink — it is a hole, and it takes the colour of whatever is behind the type. On a light page that is exactly right and the letters read as lit. Set light type on a dark ground and the channel down every stroke goes dark too: it reads as a crack, not a shine, and the metal turns into a broken letter. Over a photograph, the picture runs down the middle of every stem and the surface stops reading altogether.
Where it does not belong
Body text, plainly and without qualification. The highlight is a second shape inside every letter, so at paragraph size there are twice as many edges to resolve as there are strokes, and the eye does the extra work on every word.
Anything small on screen. Below roughly 24px the channel is under a device pixel in the narrow places and the renderer drops it, so the letters close up exactly as they did under the 0.8 blur — the same failure, arriving through the screen instead of through the build.
Print at small size is the worst case. Ink spreads into the channel and closes it from both sides, and the letter that came back as a slab in the tracer comes back as a slab on the paper. On press, give it size and a flat ink.
Forms, labels, buttons, tables, navigation, running interface text, legal lines. And with a single weight and no italic, anything with a hierarchy needs a text family beside it — Mercury sets the name, and something else sets the page.
Type your own words into it at /fonts/mercury, where you can see the B and the Q do what they are supposed to. Licences start at $3.00 in the shop.