The ash of any burnt object is not regarded as holy ash.
Vibhuti (AKA bhasma,Thiruneeru,the holy ash) is the ash from the Homa. In an age-old practice, Vibhuti is made out of dried cow dung cakes, invoking Vedic rituals, during the annual Maha Sivarathri festival.
So, how does this work?
The cow dung cakes are prepared and dried in days and weeks ahead of the festival. The cakes are typically circular in nature about 10-15 feet in diameter. In more traditional households, while the cow dung cakes are prepared, the vedic chants in praise of Lord Siva - the sri rudram and chamakam are chanted.
Karukkai - semi grown grains of Paddy, plays a key role in Vibhuti preparation. Importantly this is not to be confused with Kadukkai - a native nut used in Ayurvedic preparations.
On the morning of Sivarathiri day, the spot for Vibhuti preparation is cleaned with cow dung, Gomaya and decorated with Kolams. The cow dung cakes are placed in layers with Karukkai and hay in a pyramidal or a siva lingam kind of formation called Sivarathiri Muttan. These muttan’s can be of 5-7 feet in height with a similar diameter. Setting up of the Muttan starts with spreading Karukkai on the ground. On that the cow dung cakes are placed in layers with hay, Karukkai and cow dung cakes within each layer.
On the morning of Sivarathiri, Viraja homam is performed. Then after homam, the fire is placed on the muttan and it burns out after some days. The ember is retained in the muttan for about a week or even longer and that makes the cakes not just burn but get baked, and gives it the bright white colour. Within the muttan, the hay transfers the fire from one layer to another while the Karukkai ensures that the muttan fumes and does not get burnt out instantly. Around the next full-moon day, the muttan can be dismantled and the cakes now, milky white - if all goes well, can be taken and used. Vasthrakayam or filtering through a white cotton cloth may be done if needed. It is also said that late season fog prevalent during Sivarathiri contributes to the white colour of the Vibhuti.
This procedure can also be done on Monthly Sivarathiri day - which typically falls on the Chaturdasi day preceding Amavasya.
The cow dung from Indian breed cows are best used and foreign cows like Jerseys or mixed breeds are to be avoided. This is where by using traditionally prepared Vibhuti, we are contributing to protection of native cows and sustenance of Village economy.
In households where agnihotram / Oupasanam is performed the ash from that can be regarded as Vibhuti.
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