Saltfire Day 51 20 August 2026
Coal
How do you make Coal in 4 merges?
- 1 Ember + Salt Ash
- 2 Ash + Ember Charcoal
- 3 Ash + Ash Cinder
- 4 Charcoal + Cinder Coal
Why is 4 merges the shortest possible?
Day 51 asked for Coal — a tier-3 element, one of the made things — and it goes in four merges. Not fewer: par is worked out across the whole recipe tree before the puzzle ships, and then proved by replaying the chain above against the game's own rules, starting from nothing but Salt, Ember, Dew and Breath. If that replay had spent one step more or one step less, the build would have failed and this day would never have run.
One merge comes straight out of the primordials — Ash — and everything else is built on top of that. The last step is Charcoal + Cinder, which is where Coal finally condenses.
Now look at Ash: made once, then wanted in two different merges. That is the whole reason the floor is four and not six. A step buys you an element for the rest of the run, so par counts distinct pairs, not branches of a tree — the second time the chain reaches for Ash it is already sitting in the tray, free. Counted as a tree, with a fresh derivation for every single ingredient, this same solution reads as six merges.
Coal has four recipes in the tree, so the route above is the cheapest way in rather than the only one. Another chain of the same length is quite possible; a longer one is far more likely. One step fuses an element with itself (Ash + Ash). Self-merges are legal moves and a few elements only come out that way — always worth a try when a run stalls. Dew and Breath never appear in the short way through — though nothing tells you that while you are playing, which is rather the point.