What Is RSO (Rick Simpson Oil)?

RSO, or Rick Simpson Oil, is a full-spectrum cannabis extract made through ethanol extraction. Unlike concentrates that target isolated cannabinoids, RSO retains the full chemical profile of the plant: cannabinoids, terpenes, flavonoids, and other bioactive compounds. The result is a dark, viscous oil with a tar-like consistency that represents one of the most complete extractions you can produce from cannabis or hemp flower.

The process itself is straightforward, but the chemistry behind it matters. Ethanol is a polar solvent, meaning it pulls a broad range of compounds from plant material, including chlorophyll, waxes, and lipids. This is what gives RSO its characteristic dark color and full-bodied chemical profile. Understanding solvent polarity and its effect on extraction selectivity is critical to producing quality RSO consistently.

Equipment and Materials You Need

Before starting, gather the following:

  • Cannabis or hemp flower: 1 ounce (28g) minimum. Higher quality input produces higher quality output.
  • Food-grade ethanol (190 proof or higher): Everclear is the most accessible option. You need roughly 1 gallon per ounce of flower.
  • Two large glass or ceramic mixing bowls
  • Wooden spoon or silicone spatula for stirring
  • Cheesecloth or fine mesh strainer
  • Unbleached coffee filters for secondary filtration
  • Rice cooker or double boiler for solvent evaporation
  • Plastic syringes (no needle) for dosing and storage
  • Ventilation: Work outdoors or in a well-ventilated area. Ethanol vapor is flammable.

Safety note: Never use an open flame near ethanol. Use electric heating elements only. Ethanol has a flash point of approximately 16.6°C (62°F), which means it can ignite at room temperature in the presence of a spark or open flame.

Step-by-Step RSO Extraction Process

Step 1: Decarboxylation (Optional Pre-Step)

If you want your RSO to be orally active without further heating, decarboxylation converts THCA to THC and CBDA to CBD. Spread your flower on a baking sheet lined with parchment paper and bake at 240°F (115°C) for 40 minutes. Some producers skip this step because the solvent evaporation phase generates enough heat to partially decarboxylate the extract. However, pre-decarbing ensures complete conversion and more predictable potency.

Step 2: First Ethanol Wash

Place your flower in a large glass bowl and pour enough ethanol to fully submerge the material, plus about an inch above. Stir gently for 2 to 3 minutes. This first wash extracts the majority of the cannabinoids and terpenes. Do not over-agitate or soak for extended periods. Longer contact time pulls more chlorophyll, waxes, and lipids, which darken the oil and reduce purity.

Step 3: Strain and Filter

Pour the ethanol solution through cheesecloth into a second clean bowl, squeezing gently to recover as much liquid as possible. For cleaner RSO, run the filtered liquid through an unbleached coffee filter. This removes fine plant particulate but does not remove dissolved chlorophyll or waxes.

Step 4: Second Wash (Optional)

You can perform a second wash on the same plant material to recover residual cannabinoids. Add fresh ethanol, stir for another 2 to 3 minutes, and strain again. Combine the first and second wash liquids. The second wash typically yields 15 to 20 percent additional cannabinoids but also extracts more undesirable compounds. Many producers keep the first and second wash separate, using the first wash for oral RSO and the second wash for topical applications.

Step 5: Solvent Evaporation

This is where most mistakes happen. Pour the filtered ethanol solution into a rice cooker and set it to the lowest heat setting. The rice cooker provides consistent, gentle heat that keeps temperatures below ethanol’s boiling point of 173°F (78.4°C) while still driving off the solvent efficiently. As the ethanol evaporates, the liquid volume decreases and the color darkens.

Never allow the temperature to exceed 290°F (143°C). Cannabinoid degradation accelerates above this threshold, converting THC to CBN and destroying terpenes. A rice cooker’s built-in thermal switch typically prevents overheating, which is why it is the preferred tool for this step.

The process takes 3 to 4 hours depending on the volume of ethanol. The oil is ready when it stops bubbling and becomes a thick, dark, viscous liquid. Small bubbles indicate residual solvent still evaporating. Wait until all bubbling stops completely.

Step 6: Collection and Storage

While the RSO is still warm and fluid, draw it into plastic oral syringes using the plunger. Once cooled, RSO becomes extremely thick and difficult to work with. Store filled syringes in a cool, dark place. RSO remains stable for months when kept away from heat, light, and oxygen. Refrigeration extends shelf life but makes the oil harder to dispense. Warming the syringe briefly under hot water restores workability.

Understanding RSO Potency and Composition

Well-made RSO from high-quality cannabis flower typically tests between 50 and 70 percent total cannabinoids. This is lower than ethanol shatter or distillate because RSO retains chlorophyll, lipids, and plant waxes that dilute the cannabinoid concentration. However, many users and patients prefer RSO specifically because of this full-spectrum profile.

The entourage effect, where cannabinoids and terpenes work synergistically, is maximized in full-spectrum extracts like RSO. This is the primary reason RSO has remained popular despite the availability of more refined concentrates. The trade-off is simple: higher purity concentrates isolate specific compounds, while RSO preserves the whole-plant chemistry.

Common Mistakes and How to Avoid Them

  • Soaking too long: Extended ethanol contact (over 5 minutes) pulls excessive chlorophyll and waxes. Keep wash times short.
  • Using isopropyl alcohol: Isopropyl (rubbing alcohol) contains denaturants and is not food-safe. Always use food-grade ethanol. If 190-proof Everclear is unavailable in your state, 151-proof works but yields a slightly less potent product due to water content.
  • Overheating during evaporation: Temperatures above 290°F degrade cannabinoids. Use a rice cooker or double boiler with temperature monitoring.
  • No ventilation: Ethanol vapor is heavier than air and accumulates at ground level. Always work in a well-ventilated area, preferably outdoors.
  • Skipping filtration: Unfiltered RSO contains plant particulate that affects taste and consistency. Double-filter through cheesecloth and coffee filters.

RSO vs. Other Cannabis Extracts

RSO occupies a unique position among cannabis extracts. Here is how it compares:

  • RSO vs. Distillate: Distillate is a refined, high-potency extract (85 to 95 percent cannabinoids) produced through short path or wiped film distillation. RSO is unrefined and retains the full plant profile. Distillate is nearly flavorless; RSO has a strong, earthy, sometimes bitter taste.
  • RSO vs. CO2 Oil: CO2 extraction produces a cleaner extract with better terpene preservation, but it requires expensive equipment ($50,000+). RSO can be made at home for under $50 in materials.
  • RSO vs. BHO: Butane extracts target trichome heads and produce lighter-colored concentrates (shatter, wax, live resin). RSO extracts the whole plant, producing a darker, more complete extract.
  • RSO vs. Tincture: Both use ethanol, but tinctures retain the solvent as the delivery vehicle. RSO evaporates the ethanol completely, leaving only the concentrated oil.

Frequently Asked Questions

How long does it take to make RSO at home?

The full process takes approximately 4 to 6 hours from start to finish. The ethanol washes and filtration take about 30 minutes. Solvent evaporation in a rice cooker takes 3 to 4 hours depending on volume. If you include a decarboxylation pre-step, add another 40 minutes of oven time.

What is the best solvent for making RSO?

Food-grade ethanol at 190 proof (95% concentration) is the standard. Everclear is the most widely available option. Never use isopropyl alcohol, denatured alcohol, or methanol. These contain toxic additives that cannot be fully removed during evaporation and pose serious health risks.

How much RSO does one ounce of flower produce?

One ounce (28 grams) of quality cannabis flower typically yields 3 to 5 grams of RSO, depending on the starting material’s cannabinoid content and how thoroughly you wash. This represents roughly a 10 to 18 percent return by weight. Higher potency flower yields more concentrated RSO.

Does RSO need to be decarboxylated?

If you plan to consume RSO orally (under the tongue, in capsules, or mixed into food), decarboxylation is recommended. Raw THCA is not psychoactive; it must be converted to THC through heat. The solvent evaporation step provides some decarboxylation, but it is not complete or consistent. Pre-decarbing at 240°F for 40 minutes before extraction ensures full activation.

Can you make RSO from hemp flower?

Yes. Hemp-derived RSO follows the exact same process. The resulting oil will be high in CBD rather than THC, with total cannabinoid content typically between 40 and 60 percent. Hemp RSO is legal under the 2018 Farm Bill provided the final product contains less than 0.3% delta-9 THC by dry weight.

Is RSO the same as cannabis oil?

“Cannabis oil” is a broad term that can refer to any oil derived from cannabis, including distillate, CO2 oil, MCT-based tinctures, and RSO. RSO specifically refers to the full-spectrum ethanol extract made using the Rick Simpson method. The key difference is that RSO retains the complete chemical profile of the plant, while most commercial cannabis oils are refined to isolate specific cannabinoids.

How should RSO be stored for maximum shelf life?

Store RSO in airtight plastic syringes or glass containers in a cool, dark location. Exposure to heat, light, and oxygen degrades cannabinoids over time, converting THC to CBN and reducing potency. Properly stored RSO remains effective for 6 to 12 months. Refrigeration extends shelf life further but thickens the oil. Run the syringe under warm water for 30 seconds before dispensing refrigerated RSO.

Why is RSO so dark compared to other extracts?

RSO’s dark color comes from chlorophyll, lipids, and plant waxes that ethanol extracts along with cannabinoids and terpenes. These compounds are not present in more refined extracts like distillate or BHO shatter, which use either non-polar solvents or post-processing steps (winterization, filtration) to remove them. The dark color is not an indicator of quality; it simply reflects the full-spectrum nature of the extraction.

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