Why is copper peptide serum blue, and what if it turns green?
Short answer
GHK-Cu is naturally sapphire blue. Green or brown means it may have oxidized and lost stability.
Explanation
Disodium EDTA is included to delay oxidation. The serum is kept at pH 6.0–6.5, since peptides are sensitive to pH jumps, and has a 6-month shelf life.
What to do
- Stir peptides in by hand or at the lowest mixer speed.
Source: The Big Book of Homemade Skin Care — Copper Peptide Renewal Serum