by Dr E. Ramanathan PhD
Liquid degreasing chemical has the following characteristics:
- Alkaline base (pH > 9)
- Contains non-chlorinated surfactants and dispersants
- Includes corrosion inhibitors for mild steel and other metals
- Free from phenols, chromates, nitrites, and cresols
- Soluble in water
- Safe for ferrous and non-ferrous metals
- Can be used via immersion, wipe, ultrasonic, or spray application
✅ Suggested Alkaline Liquid Degreaser Formulation (Multi-metal compatible):
| Component | Function | % w/w |
|---|---|---|
| Sodium Metasilicate Pentahydrate | Alkaline builder, cleaning power | 5.0 |
| Sodium Carbonate (light) | Buffering agent, alkalinity | 4.0 |
| Non-ionic Surfactant (e.g., NP-9 or Fatty alcohol ethoxylate) | Emulsifier, degreasing | 5.0 |
| Anionic Surfactant (e.g., Sodium Lauryl Sulfate) | Foaming & wetting agent | 2.0 |
| EDTA (Tetrasodium salt) | Chelating agent (water hardness) | 1.0 |
| Sodium Gluconate | Corrosion inhibitor | 2.0 |
| Benzotriazole or Tolyltriazole | Copper/brass corrosion inhibitor | 0.3 |
| Isopropyl Alcohol (IPA) | Helps solubilize oils/grease | 3.0 |
| Deionized Water | Solvent/Base | to 100% |
🧪 Key Characteristics:
- pH (1% solution): ~11.0–12.5
- Appearance: Clear to slightly hazy liquid
- Application Methods: Wipe, dip, spray, ultrasonic cleaning
- Compatibility: Ferrous metals, aluminum, copper, and alloys
- Shelf-life: 6–12 months in sealed containers
- Corrosion Protection (temporary): Up to 4 weeks indoors depending on dilution and conditions
Application concentration can vary depending on the type of contamination, metal type, and cleaning method (dip, spray, or brush).
✅ Recommended Concentrations by Application Method:
🔄 Adjustments Based On:
- Heavy Grease/Carbon Contamination → use higher end of range or pre-soak.
- Soft Metals (Aluminum, Brass) → keep pH lower (3–5% solution).
- Ultrasonic Cleaning → 3–5% with agitation at 40–60°C.
- Rinse Required? – Generally no rinse is needed unless high residues remain or sensitive post-processes follow (like painting or coating).
✅ Recommended Dilution Concentrations by Application Method
| Application Method | Typical Dilution (% w/w) | Temperature Range | Remarks |
|---|---|---|---|
| Dip/Immersion | 3–8% | 40–60 °C | Soak for 5–15 min; effective for complex geometries. |
| Spray Washing | 2–5% | 45–65 °C | High-pressure spray improves penetration into crevices. |
| Brush or Wipe-on | 5–10% | Ambient to 50 °C | For localized cleaning; rinse if residues remain. |
| Ultrasonic Bath | 3–5% | 45–60 °C | Use for 5–10 min; cavitation boosts removal of fine oils, residues, and polishing paste. |
🛠 Notes:
- For aluminum or zinc alloys, keep dilution closer to 3% to reduce risk of etching.
- Post-cleaning rinsing may be omitted if corrosion inhibitors are included and the cleaned part is not going into a post-coating/painting line.
- Ultrasonics improve performance significantly at lower concentrations compared to immersion alone.
Ultrasonic Cleaner Bath Design
⚗️ Instructions for Preparing 100 L Batch @ 5% in Ultrasonic Cleaning Bath:
- In a clean mixing tank, add ~80 L of DI water.
- With slow agitation, add 1.135 kg of the pre-mixed concentrate (active ingredients).
- Stir until all components dissolve (especially surfactants and silicates).
- Top up with water to 100 L.
- Heat to 45–60 °C and add to ultrasonic bath.
🧪 SOP: Specific Gravity Measurement of Alkaline Degreasing Product
Objective
To determine the specific gravity (SG) of the alkaline liquid degreaser using a standard laboratory method.
Materials Required
- Clean 100 mL pycnometer or specific gravity bottle
- Analytical balance (±0.01 g accuracy)
- Thermometer (range 20–30 °C)
- Distilled water
- Degreaser sample (at room temperature, ~25 °C)
- Tissue or lint-free cloth
Procedure
- Clean and dry the specific gravity bottle thoroughly.
- Weigh the empty bottle:
📌 Record as W₁ (g) - Fill the bottle with distilled water at 25 °C and weigh:
📌 Record as W₂ (g) - Empty, dry, and refill the same bottle with the degreaser sample at ~25 °C.
📌 Record as W₃ (g) - Calculate Specific Gravity using the formula:
Example Calculation
- W₁ (Empty): 45.00 g
- W₂ (With water): 145.00 g
- W₃ (With degreaser): 153.00 g
🏷️ Suggested Product Label – Alkaline Degreasing Chemical
Product Name: Caustic Alkaline Liquid Degreaser
Type: Alkaline Liquid Degreaser
Appearance: Clear to slightly hazy liquid
pH (1% solution): 11.5 ± 0.2
Specific Gravity (@25 °C): 1.08 ± 0.02
Active Ingredients: Non-ionic and anionic surfactants, alkaline salts, corrosion inhibitors
Dilution Range: 2–10% depending on method
Application Methods: Dip, spray, ultrasonic, brush
Storage: Keep sealed in cool, dry place; shelf-life 12 months
Precautions: Avoid contact with eyes and skin. Wear gloves and goggles.
