noun which may take the genitive case particle 'no'
additive-free; no additives
Used primarily for food, cosmetics, and other products that contain no artificial preservatives, colorings, or chemical additives. Often appears in marketing and labeling.
このジュースは無添加で、保存料は一切使っていません。
This juice is additive-free and contains no preservatives whatsoever.
無添加の化粧品を探しています。
I'm looking for additive-free cosmetics.
天然 (natural) broadly means derived from nature, but does not guarantee the absence of additives; 無添加 explicitly states no additives were used.
Compound of 無 (mu, 'without') and 添加 (tenka, 'addition, additive'). The word 添加 itself is a Sino-Japanese term for adding or supplementing something.