Brightness, whiteness and shade: how bleached kraft is actually graded
ISO brightness, CIE whiteness, and why two 'white' kraft papers can look completely different on shelf.
A buyer asks for 'white bleached kraft'. The supplier sends a sample. The marketing team rejects it as 'too yellow'. The procurement team is confused. The issue is that 'white' is not one number — it is three.
ISO brightness (ISO 2470)
Reflectance of blue light at 457 nm. Pure white = 100. Standard bleached kraft scores 80–88, premium grades 88–92.
CIE whiteness (ISO 11475)
Measures perceived whiteness across the visible spectrum, including the effect of optical brightening agents. A higher CIE means a cooler, bluer white. Important for retail shelf appeal.
Shade — the dimension nobody specifies
Two papers at brightness 85 can have very different shades: one neutral, one yellowish, one bluish. Always request a physical control sample and approve it before order, especially for printed retail bags where colour matching matters.
"Brightness is a number. Whiteness is a perception. Shade is a brand decision."
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