Every stirred or shaken drink leaves the tin with more water in it than you poured. That water is part of the recipe, and it is the only ingredient nobody measures. You can stop guessing this week. All you need is a kitchen scale. **The challenge** 1. Put the empty mixing glass on the scale and zero it. 2. Pour in the ingredients of a spirit-forward drink you know well, and write down the weight. 3. Add ice, stir exactly as you normally would, then strain into a glass sitting on the zeroed scale. 4. Second weight minus first weight is the water you added. Divide that water by the starting weight and you have your dilution as a percentage. **Post in the comments: your number.** Just the percentage, and what you were making. That figure is yours — it comes from your ice, your glass, your hands and your stirring speed, and it is worth more than any number printed in a book. Almost everyone is surprised by how large it is. Mine used to be much higher than I thought. Full protocol: Master the Invisible Ingredient → Weigh your dilution — open to everyone, no level needed.

Sugar and acid hide each other. A drink that tastes too sour is very often a drink that is short on sugar, and a guest who says "too sweet" is frequently asking for more lime. This week, prove it on yourself. **The challenge** 1. Build a sour you know well — Daiquiri, Margarita, Whiskey Sour — three times. 2. Change ONLY the sugar: your usual amount, a third less, a third more. Spirit and citrus identical in all three. Identical. 3. Shuffle them so you don't know which is which, then rank them from most sour to least sour. **What to look for:** whether the one you called most sour is actually the one with the least sugar — because the citrus never changed. If it is, you just measured sugar masking acid, on your own palate. **Post in the comments:** your ranking, and whether you got it right. That's it. A single line is a complete answer. This one humbles almost everybody, including people who have been behind a bar for years. I'll reply to every one. The full protocol lives in THE PALATE in the classroom, which opens at Level 4 — but you don't need it to run this today. Everything you need is on the card.