Molecular Sizing: 50,000 Daltons vs. 100 Daltons
To understand hair product labels, you must understand molecular scale. Un-hydrolyzed keratin is a massive fibrous macromolecule with a molecular weight often exceeding 50,000 Daltons (Da). The intercellular spaces in a healthy hair cuticle are only 10 to 50 nanometers wide. Intact keratin cannot physically penetrate inside the hair shaft; it acts as a sacrificial surface coating that fills jagged cuticular chips and shields against heat.
Amino acids are single monomeric units with molecular weights typically under 150 Daltons (e.g., Glycine is 75 Da; Alanine is 89 Da). Because of their minuscule size, free amino acids slip effortlessly through the cuticular barrier into the deep cortex, binding with water and reinforcing the internal hydrogen and ionic matrix.
Diagnosing Protein Overload vs. Moisture Deprivation
If your hair feels stiff, dry, crunchy, and snaps easily when stretched gently between your fingers, you are suffering from 'protein overload'—the result of layering too many heavy keratin products. The hair has lost its elasticity.
If your hair stretches excessively like wet chewing gum and fails to bounce back, snapping in half, it is suffering from 'hygral fatigue' and severe protein deficiency. The fix: use heavy keratin masks for gummy, limp hair; switch to amino acid and moisture masks for stiff, dry hair.