1.Test the sample of material iron to find its composition. If the composition is up to the standars, the engineers in workshop make the raw material treatment according to the result of test.

2.The iron are put into the furnace to heat up to 1400C, and then become to fluent metal.

3.The fluent metal is poured into model. After several minutes, it turns out a rough. The model should be repaired and replace in time. The rough is picked up from the modle after 3-5 minutes.
                     
4.The fluent metal is poured into model. After several minutes, it turns out a rough. The model should be repaired and replace in time. The rough is picked up from the modle after 3-5 minutes.
                      
5.The rough should be sprayed the first enamel homogeneously in order that the enamel and rough could cooperate better.
                      

                       
6 .Put the finished rough to the enamel woreshop. Firstly, put the rough into the furnace whose temperature is 860 for 15 minutes. Spread the enamel on the face of rough. Secondly, put it into the furnace again for 10 minutes while the temperature is 900C. Spread the enamel on the face of it. Do it again and again, total four baking and three enamel. After these procedures, it is the cast iron bathtub.

*the above are the production line and production technology, which are only for reference.