WARNING! Before lighting first fire ensure that fireback and filling are completely dry. First fire should be small and gradual (Very small flames).
DO NOT use flammable materials (e.g. plastic packaging or fine sawdust)
Always use a firegaurd and supervise
Cracks in the fireback are liable to occur at any time, but unless they develop into larger cracks, or cause disintergration of the fireback, they are not serious