Espresso needs a grind that works with the specific brewer, basket and coffee. The source separates steam-driven and pump-driven equipment, but those broad categories do not justify a universal rule that one should always use a finer grind. Begin with the manufacturer's instructions, especially for pressurized baskets or appliances with particular restrictions.
A burr grinder designed for espresso generally offers more useful control than a blade grinder. Both flat and conical burr designs can be suitable; burr shape alone does not decide whether a grinder can make small, repeatable adjustments. Check its practical adjustment range and how consistently it delivers the amount of coffee you intend to use.
Keep the dose and target beverage yield steady while changing the grind. If flow changes, record the extraction time and taste before deciding what to adjust next. Different beans and changes during storage can require a new setting. A successful setting is therefore a working recipe for that coffee and equipment, not a permanent number on a dial or a texture description that applies to every machine.
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