Ash Preparation - Kshara 2/5

Classical information

The next step is to burn the plant completely to obtain ash from it. The texts of Ayurveda mention various methods for burning the dried plant material.

Sushruta and Vagbhata in their texts mention that the पञ्चाङ्ग (the entire plant- root, stem, leaves, fruits and flowers) of plants should be collected, dried, cut into small pieces and burnt by placing a chunk of सुधाखण्ड in the heap of the dried pieces. While burning, the plant material is kept intact with the help of तिलनाल. The ashes are collected and used for the next step in the preparation.  

Sharangadhara Samhita and Rasa Tarangini mention that the dried parts of plants which exude milky sap and plants with Kshariya guna respectively are burnt into ash using fire. The usage of सुधाभस्म शर्करा and तिलनाल as mentioned by Sushruta and Vaghbhata is not expounded by these later texts.

According to the classical texts of Ayurveda, the burning takes place in the open and until all the material is turned into a greyish white ash. Some kshara’s however, like Kalyanaka kshara (AH Chi 8/140-143 and Bhallatka kshara (Cha Chi 15/177-178) which are herbo-mineral preparations are made using the Puta method- wherein the ingredients are taken in an earthen vessel, covered with another earthen vessel and subjected to fire using cow-dung cakes. The Puta method lowers the abundance of oxygen during the burning process.

What we did and observed

Many of the practitioners follow the method advocated by Sharangadhara and Rasa Tarangini. The dried plant material is taken in an iron pan and burned till the ashes are collected in the vessel. In several commercial preparations, the burning is carried out using Muffle’s furnace where the temperature is maintained above 500 degrees Celsius. The grey/ white ashes are duly collected. In our case, Dr Pervaje had already completed this step before our demonstrations.  

Gaps Identified

• The temperature, the amount of oxygen and the duration of heat that is to be provided to achieve the grey/white ash is not precisely defined. Also, why puta method for some preparations while open heat for others is not clear.

• Lack of compositional analysis of the ash depending on plant source, method of drying and method of burning.

• No clear indication of the expected yield of ash from a defined amount of dried plant material.  

Proposed ways to address gaps

• In either method of preparing the ashes, the ashes generally contain sodium hydroxide, potassium carbonate, calcium oxide, magnesium and silica in their oxidized states, due to their interaction with air. These are elements present in the plant and due to high heat these would be oxidised to their respective oxides. The oxides and carbonates of these elements are basic in nature and thus elevate the pH levels once formed. Studies on the lines of “Chemical and mineral composition of ashes from wood biomass combustion in domestic wood-fired furnaces” should be carried out to chemically define the ash that is obtained at the end of the burning procedure. For this, X Ray Fluorescence Analysis technique can be adopted to determine the composition of the ashes obtained after burning the plant material. A low cost indicator during Kshara preparation would be the determination of pH of the dried plant material and the pH of the ash that is left after the burning process.

• Better reporting standards on the amount of fresh plant material taken, the amount left after complete drying and the amount of ash obtained after burning the plant material can be adopted.

• Pre-clinical laboratory studies to understand if kshara therapeutic properties vary if the method of drying is a by Muffle’s furnace (used by industry) vs open-air combustion (classical recommendation).

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