[Baren] Editor's comments ...
Mr. Gookin is in error here. The 'key block' was almost without exception the first block printed. The colour blocks then followed one by one, with the impressions being carefully fitted into the correct place, as determined by the black outlines.
The misunderstanding is an easy one to make, as the finished print shows every impression of having the key block printed last - the black lines are sharp and clear, unmuddied by any colours. But this is due to the extreme transparancy of the colours used; the strong black shows through them clearly.
Portions of ukiyo-e prints that show an extreme jet black though, such as hair arrangements, or black kimono, were added later - these black areas are colour areas, not key block lines ...