Soap is naturally readily biodegradable and always a good choice regardless of who made it. If you have to choose between soap and something else, choose soap. The other option might not be bad either, but make it a habit not to choose chemicals you don't fully understand. If there's something you're unsure about in the ingredient list, look it up, or choose something you know. A warning symbol is there for a reason.
If you've reached this point in your chemical-conscious journey, you've come further than most!
Congratulations, well done! You've done yourself, your health, your family's health, your local environment, and the climate a great service.
If you want to go even further, some of us are so "nerdy" that we like to calculate and examine things, there are, of course, differences between soaps as well.
Soaps acquire different properties depending on which oil/fat is saponified. Certain fats, such as linseed oil and rapeseed oil, produce rich soaps that treat and care for wood materials, while tall oil, for example, yields a slight excess of fat that doesn't have the same caring properties. Tall oil is a residual product from the paper pulp industry (paper mills). More precisely, tall oil is extracted as a byproduct of the sulfate process in paper production.
The process requires several chemicals:
Sodium hydroxide (lye) and sodium sulfide are used in the cooking of wood chips to separate lignin from cellulose.
Sulfur dioxide and other sulfur-containing compounds are used in the paper mill's process and contribute to sulfur emissions.
Tall oil soap, which is formed during the process, must be treated and further refined to become usable tall oil.
The presence of Colophony, a resin acid found in tall oil, can also occur in tall oil soap. You can be contact allergic to the resin acids in colophony, which can cause itchy rashes and eczema. For example, its presence in clothing prints can cause rashes. If you use a lot of Post-it notes, for instance, it can trigger eczema since colophony is in the adhesive. The adhesive in regular plasters often contains resin acids; if you're hypersensitive, you should choose a plaster with a different adhesive, such as one with acrylic adhesive. According to the Asthma and Allergy Association's magazine no. 1, 2025, the Occupational and Environmental Dermatological Department at Skåne University Hospital in Malmö has found that 75% of the military recruits at some Skåne regiments have developed contact allergies from the foot tape used in the military to prevent chafing during marches. The contact allergy arose due to colophony in the foot tape. This is serious because colophony also contains substances that can cause allergies to perfume, fragrances, and wood materials.
From a climate and environmental perspective, there are a few more aspects to consider. Below is a comparison table addressing various factors.
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For the production of soap, often floor soap, soy is sometimes used. Soap based on soy has certain disadvantages, mainly due to problems with biodiversity and rainforest deforestation. Please inquire at your building materials store about the oil your floor soap is based on. Other problematic circumstances include:
Pesticides and artificial fertilizers are used in large quantities in soybean cultivation, especially in South America where soy expands in deforested rainforests.
Hexane, a fossil solvent, is often used in oil pressing to maximize extraction. It's a volatile organic compound with health risks and environmental impacts.
Artificial fertilizers and pesticides contribute to nitrogen leakage, soil acidification, and affect ecosystems.
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Below is a comparison table that also includes linseed oil. Linseed oil is an oil with relatively low CO2 impact, it also requires little cultivation area, however a large portion of the flax for linseed oil production is grown in Russia and China, which could possibly be classified as a problem, if nothing else, in terms of shipping.
Property | Circulated Rapeseed Oil | Tall Oil | Soybean Oil | Linseed Oil |
| Biodegradable | Yes | Yes | Yes | Yes |
| Origin | Plant-based (rapeseed) | Wood-based (byproduct) | Plant-based (soybeans) | Plant-based (linseed) |
| Environmental impact | Low, recycled material | Moderate, byproduct of forest industry | High, linked to deforestation | Low, requires small cultivation area |
| CO₂ emissions (kg CO₂-eq/kg) | ~0.1–0.3 | ~0.2–0.6 | 4–6 | ~0.2–0.5 |
| Energy consumption (MJ/kg) | Low | High | High | Moderate |
| Agricultural land | No new land needed | No new land needed | Approx. 0.7–1.2 m²/kg | Small cultivation area |
| Water consumption | Minimal | High | 2,300–3,500 liters/kg | Low |
| Chemical use | No extra | NaOH, Na₂S, SO₂ | Pesticides, hexane | No extra |
| Biological impact | Reduces waste | Affects forest ecosystems | Deforestation, erosion | No deforestation, low impact |
| Processing steps | Filtration and cleaning | Chemical separation, refining | Cultivation, extraction, refining | Pressing and filtration |
| Availability and circularity | Limited recycled amount | Dependent on forest industry | Large-scale but environmentally burdensome | Limited by cultivation capacity |
Conclusion:
Circulated rapeseed oil has the lowest climate impact and is the most sustainable choice. It's also the only one that's based on circularity.
Tall oil is better than newly produced rapeseed oil in terms of CO2, but requires chemicals and is dependent on the forest industry and thus continued logging.
Soybean oil is the most environmentally burdensome oil.
Linseed oil has low environmental impact and requires little cultivation area, but often comes from Russia and China, and is not circular.
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