Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

If you have old Esbit tabs that have been exposed to high humidity over time, they will like perform much as Nick has described (and shown in a video recently). However, if you lay those same old "hydrated" tabs out on a hot sunny day with low humidity, you may in fact substantially revitalize them. Heating in a nice warm oven would likely have the same effect, but with some added risk, so I prefer the more natural outdoor solar method!