We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What Is Steam Distillation?

By Phil Riddel
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Steam distillation is a method of isolating compounds which decompose at high temperatures by distilling them in such a way that steam is introduced into the raw material. Normally, distillation is employed in order to separate a substance from another substance with a higher boiling point. The mixture is heated to the boiling point of the substance to be extracted and the vapor cooled and condensed. This technique, however, is not suitable for compounds which decompose below their boiling points. For these compounds, steam distillation can be used, providing the compound is not miscible with water.

The boiling point of a liquid depends on the relationship between its vapor pressure and atmospheric pressure. The vapor pressure increases with temperature and on heating, the liquid will boil at the point where the vapor pressure equals the pressure of the atmosphere. Thus boiling can be achieved either by heating the liquid or by reducing atmospheric pressure. Some liquids, however, decompose at a temperature lower than their boiling point at normal atmospheric pressure. One solution to this problem is to use vacuum distillation or to distill under reduced pressure, so that the liquid boils at a lower temperature; another solution is steam distillation.

Where the compound of interest, normally an oil, is not miscible with water and has a higher boiling point, the vapor pressure of the two combined is the sum of their separate vapor pressures and so will be greater than that of the compound alone. The increase in vapor pressure achieved by mixing the compound with water or steam reduces the boiling point, allowing it to be distilled without decomposition. Normally, much more water than oil is distilled, but on cooling and condensing into a receiver, the two form distinct layers from which the oil can easily be separated. To maximize the amount of oil that is extracted, it is usual to have an excess of water over oil. In some cases, the material containing the oil is simply mixed with water and heated, while in other cases, the water may be boiled in a separate container and the resulting steam fed into the material being distilled.

A common application for steam distillation is the isolation of essential oils from plant material, such as herbs and spices. These oils can be used in flavorings, perfumes and in aromatherapy. Some have medical uses. Examples of essential oils often extracted by steam distillation are eucalyptus, cloves, orange, mint and citronella.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.