Why silk screening by hand? It creates slight natural variations that give the pattern subtle depth.  
Postalco Plaid is hand silk-screen printed at the Okuda Senko in Hachioji, Tokyo. 
There are long narrow tables. 25 meters. The length of a swimming pool. The fabric is stretched the full length and hand-printed using exquisitely adjusted dyes. 
After the colors have been applied back and forth across the long board, thefabricis washed for softness.
The cloth is rolled up and steamed in a huge, custom built steamer box. 
Only after these various processes are completed by the craftsmen are the plaid shirts ready to be sewn.