Pak Nai (Chinese: 白泥) is a wetland area, partly mud-bank, surrounded by mountain ranges, in the Yuen Long District of Hong Kong facing Deep Bay (aka. Shenzhen Bay). Pak Nai makes up the coastline as Sheung Pak Nai (上白泥) and Ha Pak Nai (下白泥) geographically.
Silver retention techniques have been developed to “create a distinguishing visual style” for some photographers. Some labs refer to the technique as silver retention, bleach bypass, or skip bleach. In all of these processes, varying amounts of silver are left in the print or negative film stock. And, no matter what it is called, the end results are very similar.