Carbon analysis in glass is a very difficult task. In the production of glass with Roman wood-fired glass furnaces, one can expect carbon contamination from absorption of fuel gases and/or powdery residues from furnace walls in the glass melt, and also residues from plant-ash used as flux. Sometimes carbon was intentionally added to get a distinct colour to glass. We have developed a highly sensitive non-destructive nuclear technique for carbon analysis by deuteron activation based on C-12(d,n)N-13 reaction. The method is simple, rapid and can help archaeologists understand more about the purity of ancient glass production and contamination problems associated with it. The theoretical detection limit for carbon is 5 ppm. The method is also suitable for carbon analysis of pottery.