Ever wondered why a lot of Delhi’s medieval monuments—the ones with plastered exteriors, not stone—have that blackened look about them?
A view of Moth ki Masjid, with its blackened domes.
With Delhi’s humid climate (particularly the fact that several months of the year are taken up by the monsoon) means that there’s a fair amount of rainwater falling on buildings. And rainwater, if preventive measures are not taken, can seep into buildings and eventually cause structural damage. To avoid this, medieval masons used ‘organic mortar’ to construct: the mortar, besides containing more ‘usual’ building materials like rubble or limestone, also contained organic ingredients: cow dung, yoghurt, urad dal (black lentils), fenugreek, and wood apple pulp. The organic nature of the mortar made it breathable, thus preventing waterlogging and prolonging the life of the building.
Organic mortar, however, does have a downside: just because it’s organic, it is prone to organic growth, and over the course of just a year can begin to acquire a coat of black, thanks to algae growing on the surface. Hardly surprising, then, that over centuries, some buildings become so black that the colour almost seems planned.
Jahaaz Mahal. You can see how the mortar has gone black here.
Nowadays, a lot of conservation work continues to use traditional techniques, including the use of organic mortar—which means that even recently-restored buildings can have blackened surfaces soon after work’s been done on them. Rest assured: it’s all for the best.
The use of organic mortar isn’t restricted to Delhi; organic mortars were used, though sometimes with regional differences in the ingredients, in other parts of India as well. For example, in Hyderabad’s Golconda Fort, the organic mortar included eggs and chana dal (Bengal gram).
Dustedoff 
For you, I wouldn’t have know so many things!
Thank you from the bottom of my heart! :)
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Harvey, that’s so sweet of you! Thank you. :-)
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That is so interesting, Madhu. Like Harvey, thank you! While I knew about cowdung being used (I’ve seen it mixed with mortar in Kerala), I’d no idea about the use of yoghurt or eggs, or fruit pulp or lentils.
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You’re welcome, Anu. :-) Yes, when I first heard about all these odd ingredients being added to the mortar, it surprised me, too. But when you think about why it’s done, it makes a lot of sense. And so many of these traditional techniques are so much better: for the environment, for people, for – well, so much.
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Hey, Thanks… this is very interesting! :-)
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Thank you! Glad you found that interesting. :-)
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dustedoff,
Had no idea what these monuments were made of and why they turned back.
Thanks for sharing its truly informative.
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Thank you! :-)
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My mum used to always talk about the durability of these ancient methods of construction. I grew up listening to my mum, so yes I did have a general idea about this.
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I wish I could have met your mother. She seems like such a fascinating person.
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On a National Geographic show on Taj Mahal, the workmen entrusted with maintaining it said that they used traditional methods and I remember them using jaggery and some other stuff that I cant remember. Even for the Great Wall of China, a TV show mentioned that they used rice paste as an adhesive for the stones.
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I find that very interesting, about rice paste being used at the Great Wall of China! Thanks for sharing that bit of information – I hadn’t known it.
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