 In some images , Hu employed a blind embossing technique ( known as " embossed designs " ( <unk> , <unk> ) or " embossed blocks " ( <unk> , <unk> ) , using an <unk> , imprinted block to stamp designs onto paper . He used this to create white relief effects for clouds and for highlights on water or plants . This was a relatively new process , having been invented by Hu 's contemporary Wu <unk> , who was also a Nanjing @-@ based publisher . Wu had used this technique for the first time in his book Wisteria Studio Letter Paper ( <unk> <unk> <unk> , <unk> ) , published in 1626 . Both Hu and Wu used embossing to create decorative writing papers , the sale of which provided a sideline income for the Ten Bamboo Studio . 
