Mercado Slots

Measure the colour you pulled out of a mushroom, and learn how to repeat it

Mercado Slots is a dye bench for the colours that come off the forest floor. You dye wool or cloth with fungi and lichens, photograph the finished skein next to any grey or white card, and the app 📱 reads the shade back to you as numbers 🔢 instead of a guess. Drag ✋ one reticle onto the card and one onto the yarn: it balances the photograph against the neutral, samples the skein, and reports lightness, chroma and hue angle with a depth class and a hue family. Then it ranks that reading against a forty-swatch atlas and names the dyestuff, mordant and pH that would land there, with a delta bar per candidate and a plain-words correction for the next pot.

For the dyer with a pot already on: set the bath first. Weigh the goods and Mercado Slots works everything else out as a percentage of it — grams of dyestuff at the ratio for that species fresh or dried, grams of mordant, litres of water, pH, temperature and time ⏱️, an exhaustion curve, and a verdict that flags which of ten named faults the recipe is inviting.

For the forager coming home with a basket: Mercado Slots draws and describes twenty dye species, fourteen fungi and six lichens, each with its pigment class, where it grows, the extraction method that suits it, a lightfastness rating and a row of five swatches showing what alum, iron, copper, tin or no mordant will do to it.

For the note 📝-keeper: every reading lands on a shade card grouped by hue run, so a year 🗓️ of dyeing reads as a card rather than a list 📋. Any reading can be drawn as a shade card image 🖼️ — the swatch, the illustration and the whole register, ruled and eyeletted — and filed straight into your photo library.

For the sceptic: the colour maths is ordinary colour science, done ✅ on your device 📱. Mercado Slots works offline 📴, keeps your card on this phone, and asks for the camera 📷 only at the moment you point it at a skein.