No Crema: Causes & Fixes

No crema at all and crema that disappears fast are two different problems — the guides below cover both: documented machine-specific causes for no crema, and the real chemistry behind why crema fades even on a good shot.

Breville Espresso Machine Troubleshooting Breville's own documented fixes for descaling, no crema, water flow, grinder, and steam wand problems, centered on the Barista Express with notes on what's different for the Bambino and Oracle.
Gaggia Espresso Machine Troubleshooting The Classic Pro's own official descaling process, filter-basket and tamp specs, group-gasket leaks, and the numbered error codes Gaggia actually publishes for its super-automatic line, sourced from Gaggia's own maintenance pages.
Why Does My Espresso's Crema Disappear So Fast? Peer-reviewed foam research on why crema is built to fade within minutes, the counterintuitive finding that very fresh beans make it fade faster, and why persistence isn't a quality signal.
Moka Pot vs. Espresso Machine vs. AeroPress: What's the Difference? Real pressure figures for each method, why AeroPress and moka pot can't produce true espresso or crema, and a direct answer on which one actually fits your routine.