Here's a straight gray card out of the camera RAW (NEF) opened in Windows File Manager/Explorer between a 'No Filter' shot and a Lee "Big Stopper" 10-stop ND. No processing other than JPG size to post.
The "Big Stopper" goes blue, and some crank up the Kelvin about 4,000K to compensate if they don't want to in post. The B+W goes the other way into the red and they suggest to use their IR filter in conjunction with their 10-stop ND.
Really don't know why B+W/Schneider or Lee cannot get it right, or agree they are off and correct it after all these years. I can't see it related to film either as they still go opposite directions. Maybe Lee thought it was most useful to water shots and they wanted the water more blue? B+W seems to want you to buy another filter to fix it.
SG
