BASF Test Brick – Old Logo, Mold Pip Stud, With Roman Numerals (VII)

Many of the bricks from this mold show black marks like those shown in this photo.

Wikipedia

Moulding defects:
Burn marks

Alternative name:
Air burn/gas burn/dieseling

Descriptions:
Black or brown burnt areas on the part located at furthest points from gate or where air is trapped

Causes:
Tool lacks venting, injection speed is too high

[Original post and comments on Flickr.]