Para amino phenol(PAP)

Chemical Name-Para Amino Phenol / 4-Aminophenol
Chemical Formula -C₆H₇NO
CAS Number -123-30-8
Molecular Weight -109.13 g/mol
Appearance - light to dark brown powder
Odour-Faint characteristic odour
Purity- ≥ 98% (cosmetic/technical grade)
Melting Point -186°C – 190°C
Boiling Point- 284°C
Density -1.29 g/cm³
Solubility in Water -Slightly soluble (~11 g/L at 20°C); freely soluble in hot water
Solubility in Alcohol -Soluble in ethanol and methanol
pH (1% aqueous solution)- 5.5 – 7.0
Flash Point- 153°C
Storage Condition -Cool, dry, dark place; store in airtight containers away from oxidizing agents

Delivers consistent, uniform colour coverage including grey coverage
Excellent oxidative coupling efficiency for vibrant, true-to-shade results
Compatible with a wide range of dye couplers and alkaline systems
Stable in alkaline pH environments typical of hair colour formulations
Available in high-purity cosmetic grade for reliable batch-to-batch consistency

Step 1 – Prepare Your Base Dissolve PAP in a warm alkaline solution (pH 9–10) using distilled water. Adding a small amount of sodium sulfite (0.1–0.5%) helps prevent premature oxidation and extends shelf life of the formulation.

Step 2 – Combine with Dye Couplers Mix PAP with your chosen dye couplers (e.g., resorcinol, m-aminophenol, or 2-naphthol) in the required ratio to achieve the target shade. Typical PAP-to-coupler ratio is 2:1 to 3:1 depending on the desired colour depth.

Step 3 – Add Alkaline Carrier Incorporate into an ammonia or ethanolamine-based cream or gel base. Maintain pH between 9.0 – 10.5 for optimal oxidative coupling during application.

Step 4 – Mix with Oxidant at Point of Use Just before application, mix the colour cream with a barium peroxide developer (typically 3% – 6% / 10–20 vol) in a 1:1 or 1:1.5 ratio. Apply immediately after mixing.

Step 5 – Application

Apply evenly to dry or slightly damp hair using an applicator brush
Leave on for 25–45 minutes depending on desired colour intensity and grey coverage
Rinse thoroughly with lukewarm water, then shampoo and condition

⚠️ Safety Reminders

Always conduct a 48-hour patch test before use
Use gloves during formulation and application
Store PAP in a cool, dry, airtight container away from light and moisture
Comply with CDSCO and BIS regulations for finished cosmetic products in India