Commercially obtained combustion aids typically consist of cordierite, fused silica or Si/SiC, which cannot meet the high thermal and also mechanical requirements in the necessary context, or only in a highly limited manner. The invention relates to a glass-ceramic combustion aid in the form of a non-porous keatite glass ceramic without a vitreous surface layer. Said combustion aid has high thermal stability and resistance to thermal shocks, practically no mechanical interaction, especially no porosity and adhesive effects, with the product to be baked, and can also be obtained in large formats having small thicknesses, as a mechanically stable bearing plate.