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Making Medicine: Gaos – Plasters/Pastes

by NYIA Instructor Adam Wasserman L.Ac.

This article is the first in a series of articles that  focus on the processes of making medicine. It’s easy to walk into a pharmacy in Chinatown and walk out with packets full of herbs, but turning those herbs into medicinal products such as teas, pills, ointments and the like can be difficult. We will detail some of the methods for creating those products here.

Like everything, making medicine is a skill, one that must be practiced and perfected over time and through repetition. The procedures that we detail here should not taken as gospel. Instead they should be taken as a starting point for experimentation. These recipes will be like those from your grandmother’s kitchen, add “a little” salt, add a “dash” of cinnamon. Chinese medicine is not an exact science, it is an art form. Finding the right consistency for these medicines takes trial and error, and different practitioners desire different consistencies. We encourage you to try the recipes for yourself.

Zheng Gu Tui Na San Huang San Gao
Zheng Gu Tui Na San Huang San Gao


Today we will focus on making gao (膏). Gao is often translated as plaster, but the character is also used to mean paste, cream or ointment. In Chinese medicine, gaos are a suspension of ground herb in a paste like medium that allows it to be spread on the skin. They are usually prepared in advance so that they can be applied quickly. In addition to the properties of the herbs within the powder, the medium itself is considered an herb as well. The medium can guide the formula to a particular layer or region of the body, and can also be used to accentuate or moderate the temperature of the formula.

We will be using a mixture of oil and beeswax as our medium. This medium is neutral in temperature and provides an appropriate consistency for usage. When mixed properly, the beeswax also acts as a preservative, allowing the gao to keep for an extended period of time without spoiling. For our formula, we will be making a modified san huang san (三黄散). San huang san is a traditional Chinese trauma formula designed to reduce swelling, clear heat, move qi and blood, and kill pain.

Ingredients and Supplies
Ingredients and Supplies


For this project we will need the following tools:

  • A measuring cup
  • A pot (stainless steel or ceramic are best)
  • Several glass jars (to store the finished gao in)
  • Several spoons (to stir and test the mixture)
  • A fine mesh sifter
  • An herb grinder (if you do not purchase the herbs already ground)
  • A stove
  • A grater
  • Paper plates or newsprint paper

In addition to the above mentioned tools, we will also need some supplies:

  • Herbs to Grind
    Herbs to Grind


  • Oil (Sesame oil is traditional, but most food grade oils should suffice)
  • Herbs:
    • 20 grams of da huang – 大黄
    • 20 grams of huang qin – 黄芩
    • 20 grams of huang bai – 黄白
    • 20 grams of zhi zi – 栀子
    • 20 grams of pu gong ying – 蒲公英
    • 20 grams of hong hua – 红花

The first step is to grind the herbs into a fine powder. Your herbal pharmacy may be willing to grind the herbs for you, but they generally require a minimum quantity of herbs to do so. This is because the grinding machines that they have are large and cannot grind small quantities. In general, the minimum amount is 1 lb of each herb, but your pharmacy may have a different policy. Alternately, powdered san huang san is available from Kamwo and many other herbal pharmacies.

Herbs into Grinder
Herbs into Grinder


Exercise EXTREME caution when using an herb grinder. Follow the instructions for your herb grinder to ensure safe usage.

To grind the herbs, place them in the herb grinder, screw the top on the grinder and turn it on for 30-90 seconds. For the sake of caution, when we grind herbs, we unplug the grinder before opening it. There have been reports of grinders spontaneously starting while open due to faulty wiring.

The grinder will provide a fairly rough powder, so the next step is to sift the powder in a sifter. This will allow us to separate the large chunks of herbs from the finely powdered parts. Sifting can be a multi-step process, progressively working through several different gauges of mesh. For our purposes, we do not need

Sifting Herbs
Sifting Herbs


a super fine powder, but we also do not want large chunks or stems in our mixture.

Sifting is often done over a plate or a large sheet of newsprint paper. This makes it easy to pour the finished powder into our pot and makes clean up much easier. In order to pour the finished powder simply fold the plate or roll up the newsprint and create a funnel.

Once the ground herbs are in the pot, we’ll add oil and stir until we achieve a consistency similar to thick mud.

Grating Wax
Grating Wax


Next we need to prepare the beeswax by grating it. We will be heating the mixture up and using the heat to melt the beeswax into the mixture. The beeswax shavings do not need to be particularly fine, a rough grate should be sufficient. Because we will be adding the beeswax shavings to the mixture as we heat it, we’ll need to prepare enough for the entire batch in advance. Therefore, you should grate more than you think you will need. The beeswax shavings are easy to store and will not spoil, so there is no need to be frugal in their usage.

Mixing the Wax
Mixing the Wax


Now we are ready to heat the mixture. We’ll want to cook our mixture under a low heat, because we do not want it to burn. Sesame oil has a smoke point between 350 °F (177 °C) and 450 °F (232 °C), depending on whether it is unrefined or refined. Beeswax has a relatively narrow working temperature. It melts between 144 and 147 °F (62 and 64 °C), but it will discolor at around 185 °F (85 °C). Furthermore, beeswax has a flashpoint of 400 °F (205 °C), at which point it will become volatile. If you want to be cautious, you can use a double boiler to heat the mixture, but it is not required and working over a low heat is fairly easy. Before you begin to heat the mixture, place a few spoons in your freezer. This will make testing the consistency of the mixture easier later on.

Next take the pot with our mixture and heat it over low heat. When the mixture begins to bubble, add beeswax in small amounts and stir the beeswax into the mixture as it melts. Continue to add beeswax until the mixture thickens and smooths out. This is where experience and practice will come into play. You can periodically test the mixture by taking a small amount and allowing it to drip onto one of the spoons from the freezer. The cold spoon will bring the mixture down to room temperature relatively quickly. When it is cool enough to touch, spread the gao on the back of your hand to test the consistency.

Final Consistency
Final Consistency


The ideal consistency will be a little waxier than one might expect. As the gao is applied to the skin, the warmth of the skin will permeate into the gao and soften it. If the mixture contains too much wax, then it will be difficult to scoop out of the container and difficult to spread over the skin. If it contains too little wax, then it will be easy to scoop, but it will be runny on the surface of the skin.

Applied to the Skin
Applied to the Skin


When you have achieved the desired consistency, pour the mixture into the glass jars for storage. You should label the jars with the name of the formula, as well as the date that the batch was made. You may also want to record how much oil and how much beeswax you used. This will allow you to repeat the process more easily in the future.

Finally, it is worth noting that this is only one method of making gao. Another method would be to melt the beeswax into the oil first and then add the powdered herbs second.