A parts-washer running mineral spirits keeps leaving a film of heavy grease on machined components, and the shop is also being pushed off its chlorinated cold cleaner. D-limonene comes up as the bio-based degreaser that cuts harder soils, and for the right cleaning method it does. The trick is knowing which method, because a solvent that shines in a soak tank can disappoint in a process built around a different chemistry.
D-limonene (CAS 5989-27-5) is a naturally occurring monoterpene solvent extracted from citrus peel oil, valued as a powerful, renewable degreaser and cleaning solvent. With a Kauri-Butanol value around 67, it cuts heavy oils, greases, adhesives, tar, and carbonized residues that lighter solvents leave behind, and it serves as a bio-based replacement for some harsher chlorinated and petroleum solvents in suitable cold-cleaning applications. It is also flammable, can sensitize skin, and is aquatic-toxic, so it is a high-performance solvent that still demands proper handling rather than a hazard-free one.
D-limonene properties at a glance
D-limonene is the (R)-(+) enantiomer of limonene, a clear, mobile liquid with a strong, characteristic citrus-orange odor. The property profile below explains both why it works as a degreaser and why it has to be handled like the flammable organic solvent it is. Values are typical reference figures; the Certificate of Analysis for the lot you buy governs.
| Property | Typical value |
|---|---|
| CAS number | 5989-27-5 |
| Molecular formula | C10H16 |
| Molecular weight | ~136.24 g/mol |
| Appearance | Clear, colorless to pale-yellow liquid |
| Odor | Strong citrus / orange |
| Density (20 °C) | ~0.84 g/cm³ |
| Boiling point | ~176 °C |
| Flash point | ~48 °C (flammable) |
| Kauri-Butanol value | ~67 (strong solvency) |
| Water solubility | Practically insoluble (water-immiscible) |
Why it works as a degreaser, and what it removes
The reason d-limonene works is solvency. Its Kauri-Butanol value of about 67 (ASTM D1133) is roughly double that of mineral spirits, so it dissolves a heavier set of nonpolar soils. As a terpene hydrocarbon it is at home dissolving other hydrocarbons, which is exactly what greases, oils, and many adhesives are. In practice it cuts:
- Heavy oils, greases, waxes, and cosmoline
- Adhesives, label adhesive, mastic, and gasket residue
- Tar, bitumen, ink, and carbonized or baked-on organic films
- Uncured resins and many coatings
D-limonene (CAS 5989-27-5, PubChem CID 440917) is effective neat on heavy soils and is also formulated into diluted, surfactant-emulsified, water-rinsable cleaners. Because it is water-immiscible, water-based cleaning systems carry it as an emulsion rather than a true solution.
D-limonene versus traditional solvents
The case for d-limonene is usually framed as a renewable replacement for harsher solvents, and that framing holds in the right applications, with honest trade-offs. It is bio-based and readily biodegradable, which is why formulators reach for it when reducing reliance on chlorinated chemistry like n-propyl bromide (nPB) or perchloroethylene, or on petroleum distillates and some glycol ethers. What it is not is a drop-in for every job those solvents do.
- Versus mineral spirits: roughly double the KB value, so it cuts heavier soils, but it costs more, its price tracks the citrus crop, and it evaporates more slowly.
- Versus glycol ethers: stronger on heavy nonpolar greases and renewable, but glycol ethers handle some polar soils and water-coupling tasks that d-limonene does not.
- Versus chlorinated solvents (nPB, perc, TCE): renewable, lower in several of the hazards associated with chlorinated chemistry, and a candidate where those solvents are being phased out, but d-limonene is flammable where they are not, which rules it out of closed-loop vapor degreasing.
The genuine trade-off: d-limonene buys you renewability and strong solvency, and you pay for it with flammability, a sensitization risk, slower evaporation that can leave a residue, higher and crop-linked cost, and a strong odor. Where you need a fast residue-free flash-off, a nonflammable solvent, or contact with polyolefin parts, a different chemistry is the better call. The method-by-method comparison is in d-limonene vs petroleum and chlorinated solvents.
Applications by sector
- Industrial parts and metal degreasing: immersion, soak, manual wipe, spray-and-wipe, and ultrasonic cold cleaning of machined parts, where its high KB value handles heavy oils and the slow evaporation extends bath life.
- Electronics and flux removal: used in some PCB and flux-cleaning formulations — but it is flammable, so it is restricted to processes designed for flammable-liquid handling, never open flame or vapor degreasing.
- Adhesive, label, ink, and graffiti removal: dissolves mastic, label adhesive, gasket residue, and many inks, which makes it a workhorse in remover formulations.
- Hand cleaners and HI&I: a common active in industrial hand cleaners and heavy-duty institutional and industrial (HI&I) cleaners — formulated carefully because repeated skin contact carries a sensitization risk.
- Agricultural and household-industrial cleaning concentrates: emulsifiable concentrates and all-purpose degreasing blends.
- Paint and coating stripping: softens and lifts many coatings and uncured resins as a component of stripper formulations.
- Fragrance and solvent carrier: the citrus odor and solvency make it a carrier and odorant in cleaning and specialty products.
Grades: technical, food, and high-purity
D-limonene is sold across several purity tiers, and the right one depends on the application, not just the price. Technical grade covers the bulk of industrial cleaning and degreasing, where solvency matters more than odor refinement. Food grade meets the identity and purity requirements for use as a flavor or food-contact component. High-purity grades at roughly 95–98%+ d-limonene serve fragrance, specialty solvent, and applications sensitive to color, odor character, and minor terpene impurities. Specify the grade and purity when you request a quote, because it drives both performance and cost.
Handling d-limonene honestly
Bio-based does not mean hazard-free, and treating it that way is the most common mistake. D-limonene carries three handling concerns that any program has to design around, and the Safety Data Sheet for your specific material is the governing document.
- Flammable. With a flash point near 48 °C, d-limonene is a flammable liquid. Keep it away from heat, sparks, open flame, and hot surfaces, bond and ground transfer equipment to control static, and store and use it per flammable-liquid requirements with adequate ventilation.
- Skin sensitizer. On exposure to air and light, d-limonene can oxidize to hydroperoxides that are skin sensitizers, so repeated or prolonged contact carries a sensitization risk. Use chemical-resistant gloves and eye protection and avoid skin contact.
- Aquatic toxicity. D-limonene is toxic to aquatic life. Do not discharge it to drains, surface water, or waterways; contain spills and dispose of waste solvent and rinse water in line with local regulations.
It is also a strong solvent on the equipment side: it swells and degrades polyethylene and polypropylene, can soften many rubber seals and gaskets, and can lift some paints on extended contact, while metals and PET generally tolerate it well. Always validate material compatibility on your actual parts, seals, and lines before committing a process.
Buying d-limonene in bulk
RawSource supplies d-limonene (CAS 5989-27-5) in drums, IBC totes, and pallet quantities for industrial manufacturing, maintenance, and parts-cleaning programs, with CoA documentation. To scope a quote, tell us the grade and purity you need, your volume (drums or totes), and your delivery location, along with your soil, cleaning method, rinse setup, and materials of construction. Requesting a sample to validate degreasing and compatibility on your own parts before a bulk order is the fastest way to de-risk a switch. For a broader walkthrough of specifying and sourcing industrial chemicals, see our comprehensive guide to chemical procurement.
Frequently Asked Questions
What is d-limonene?
D-limonene (CAS 5989-27-5) is a naturally occurring monoterpene hydrocarbon, C10H16, extracted from citrus peel oil as a byproduct of juice and oil processing. It is a clear, citrus-smelling liquid with strong solvency, used widely as a renewable, bio-based degreasing and cleaning solvent in industrial and formulated products.
What is d-limonene used for?
D-limonene is used mainly as a degreasing and cleaning solvent: industrial parts and metal cleaning, adhesive, label, and ink removal, electronics flux cleaning, hand cleaners, HI&I and agricultural cleaning concentrates, and paint stripping. It also serves as a fragrance component and solvent carrier in specialty formulations.
Is d-limonene a good degreaser?
Yes, for heavy organic soils in cold cleaning. Its Kauri-Butanol value of about 67 is roughly double that of mineral spirits, so it cuts oils, greases, adhesives, and tar that lighter solvents leave behind. It performs best in immersion, soak, wipe, spray, and ultrasonic methods, not in vapor degreasing.
Is d-limonene flammable?
Yes. D-limonene is a flammable liquid with a flash point near 48 °C. Keep it away from heat, sparks, open flame, and hot surfaces, bond and ground transfer equipment to control static, and store and handle it per flammable-liquid requirements. This flammability is why it cannot be used in closed-loop vapor degreasing.
Is d-limonene safe?
D-limonene is renewable and bio-based, but that does not make it hazard-free. It is flammable, it can sensitize skin on repeated contact, and it is toxic to aquatic life. Use ventilation, gloves, and eye protection, keep it away from ignition sources and waterways, and follow the Safety Data Sheet for the specific material you handle.
How does d-limonene compare to traditional solvents?
D-limonene is a renewable, bio-based solvent with strong solvency that can replace some petroleum distillates and chlorinated solvents in suitable cold-cleaning tasks. The trade-offs are real: it is flammable where chlorinated solvents are not, costs more than mineral spirits, evaporates slowly, and can leave a residue, so the right choice depends on the method and soil.
Is d-limonene biodegradable?
D-limonene is readily biodegradable under OECD ready-biodegradability test criteria. That is a specific biodegradation property and not a blanket environmental claim: d-limonene is still toxic to aquatic life and must be kept out of drains and waterways, so it must be contained and disposed of properly regardless of its biodegradability.
Does d-limonene leave a residue?
It can. D-limonene evaporates slowly and may leave a light oily film, so processes that need a clean, dry surface follow it with a water rinse on an emulsified formulation or a fast-flashing co-solvent. In soak and immersion cleaning, that same slow evaporation is an advantage because dwell time does the work.
Editorial note. This article is general technical guidance for industrial and professional users. D-limonene here is an industrial cleaning solvent, not a consumer product, and nothing here is a health or efficacy claim. Property, solvency, method, and compatibility figures are typical reference values to validate on your own soils, parts, and equipment; the Certificate of Analysis governs the material you buy. Always consult the current Safety Data Sheet (SDS) before handling. RawSource makes no warranty, express or implied, and assumes no liability for use of this information.
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