In this video, I show the carburized process of the bloomery iron gromps in a small furnace. Iron gromps are small outer parts of the iron bloom highly contaminated by the slag. I used 2.5 kg of iron gromps and 10 kg of charcoal and got 0.8 kg of high carbon steel. The high carbon material I got I will use in my next project. Tips: The diameter of the furnace is about 15 cm. To built it I used bricks and clay mixed with sand. In this experiment, I used bloomery iron gromps but ordinary soft iron also can be used (nails, scraps etc.) The temperature during the process should be enough to smelt iron. It is good to add at the first charge some pieces of slag, slag protect the bloom against burning (oxidation). For making steel do not use phosphorus iron. I use about 400 grams of charcoal for every 100 grams of the charge. The iron pieces should be small.