PEG-40 Hydrogenated Castor Oil: Uses and Safety
PEG-40 hydrogenated castor oil (RH 40) is a non-ionic solubiliser made from hydrogenated castor oil and ethylene oxide. It is used to dissolve small amounts of fragrance and essential oils into water-based products such as toners, face mists, room sprays, mouthwash and clear gels, so they stay clear instead of separating.
Last updated 7 Nov 2026
Specifications
- CAS number
- 61788-85-0
- Grades
- Cosmetic
- Hindi name
- पीईजी-40 हाइड्रोजनेटेड कैस्टर ऑयल
Products and pack sizes
| Product | Grade | Pack | Price (incl. GST) | ₹ per kg |
|---|---|---|---|---|
| Peg - 40 Hydrogenated Castor Oil (RH 40) | Cosmetic | — | ₹199 | — |
What is PEG-40 hydrogenated castor oil?
PEG-40 hydrogenated castor oil is hydrogenated castor oil reacted with about 40 units of ethylene oxide. The result is a white to pale yellow soft paste that is easy to mix with oils and then with water. It's often called by trade names such as RH 40.
- INCI name: PEG-40 Hydrogenated Castor Oil
- CAS number: 61788-85-0
- Type: non-ionic, high-HLB solubiliser and emulsifier
- Form: soft paste at room temperature, melts with gentle warming
It is a mixture of polymers, so there's no single formula or molar mass.
Grades and pack sizes at Azlok
Azlok lists PEG-40 hydrogenated castor oil (RH 40) under cosmetic raw ingredients, for toners, mists, room sprays and similar products. The listing doesn't state a pack size; check the product page. See today's price per kg.
Common uses
- Solubilising fragrance and essential oils in toners, face mists and body mists
- Room sprays, linen sprays and reed diffuser bases with water
- Clear gels and micellar-style waters
- Mouthwash and oral care flavour solubilising (with suitable grade)
- Adding oil-soluble ingredients to clear shampoos and face washes
How to use it
Basic method.
- Weigh the fragrance or essential oil.
- Add PEG-40 hydrogenated castor oil, starting at about 3 parts per 1 part oil. If the paste is stiff, warm it gently first.
- Stir the two together until fully uniform. This step matters most.
- Add the water phase slowly, a little at a time, stirring between additions.
- If it turns cloudy, make a fresh test with more solubiliser, up to about 5 or 6 parts per part oil.
The ratio needed varies with the oil; citrus and some essential oils need more than others. Formulators commonly report 1:3 to 1:6 (oil to solubiliser). Supplier sheets give a typical use level of about 1 to 10% of the finished product.
Example. For 100 ml of room spray with 1 ml fragrance, mix the fragrance with 3 to 5 g RH 40, then slowly add water, plus a preservative.
Safety and storage
- Low hazard as a raw material, but avoid getting the paste in your eyes. Rinse with water if it happens.
- Patch test any finished product on a small area of skin for 24 to 48 hours before regular use.
- Water-based mists and sprays need a preservative.
- Don't spray room or linen sprays directly at people or pets.
- Store tightly closed in a cool place, away from direct sun. It may harden in cold weather; warm gently before use.
- Keep away from children.
If you sell finished cosmetics in India, the product must meet BIS standards and CDSCO rules for cosmetics, including labelling. Check the current requirements before launch.
Choosing the right grade and pack
Because you need several parts of solubiliser for each part of oil, it gets used faster than people expect. Size your pack based on how much fragrance you plan to solubilise.
Room spray makers and personal care brands needing 25 kg or more can send a bulk inquiry.
Frequently asked questions
- How much PEG-40 hydrogenated castor oil do I need per ml of essential oil?
- Start at about 3 parts PEG-40 hydrogenated castor oil to 1 part oil by weight, mixed together before adding water. Some oils, especially citrus, need 5 or 6 parts. Test small batches and increase until the product stays clear.
- Why is my room spray cloudy even with RH 40?
- Usually there's too little solubiliser for the amount of oil, or the water went in too fast. Mix oil and RH 40 thoroughly first, then add water slowly. If it stays cloudy, raise the solubiliser ratio in a fresh test batch.
- Is PEG-40 hydrogenated castor oil the same as castor oil?
- No. It starts from castor oil, which is hydrogenated and then reacted with ethylene oxide. The result mixes with water, which plain castor oil does not do. It is a solubiliser, not a carrier oil.
- What is RH 40?
- RH 40 is a common trade-style name for PEG-40 hydrogenated castor oil, a non-ionic solubiliser. It is sold under several brand names. The INCI name on labels is PEG-40 Hydrogenated Castor Oil.
- Can I use polysorbate 20 instead of PEG-40 hydrogenated castor oil?
- Often yes, as both are solubilisers for small amounts of oil in water. They behave differently with different oils, so you may need a different ratio. Test both with your fragrance and pick the one that stays clear.
- Does PEG-40 hydrogenated castor oil need a preservative?
- The raw material itself doesn't, but any finished product containing water, such as toner, mist or room spray, needs a suitable broad-spectrum preservative. Without one, mould and bacteria can grow within weeks.