The possibility to produce deep drawing quality - bake hardenable steel grades, by introducing carbon into the strip after its recrystallization, was shown few years ago at the laboratory scale. A closed reactive zone with high contents of CO and H2 was implemented on the CRM's pilot line of continuous annealing and hot-dip galvanizing. The 0.7 mm-thick strip is carburized in less than 15 seconds with C pick-up between 10 and 70 ppm. Developments performed to isolate atmospheres could also benefit to other reactive treatments (nitriding, oxidation-reduction, etc.) aiming to improve the response of high strength steel grades to hot-dip galvanizing. The reactor design, process feasibility demonstration and product potentialities are presented.