Translator: Giada Puccinelli Reviewer: Michele Gianella
Calcium hydroxide.
A material known more commonly as lime.
I want you to keep this material in mind, as you watch the following.
7500 BC, Turkey;
7300 BC, Jordan;
79 BC, Pompeii;
14th century, Spain;
20th century, the US.
You might be wondering
what these fantastic artworks have in common with calcium hydroxide.
And this is precisely why I'm here today.
I'm here to tell you what the link is.
Some of you might have heard, of calcium hydroxide,
not as a building material -
in other words, not as a painting material,
but as a building material, and you'd be right.
Because until the revival of the Industrial Revolution, until 1827,
when Portland Cement was invented,
the main building material
used by civilizations throughout the centuries
and throughout just about the entire planet
was calcium hydroxide.
But before I continue revealing to you
the beauties and mysteries of this highly intriguing material,
I'd like to tell you something about myself.
I'm an accredited wall painter conservator,
who has been working in the field of cultural heritage
for the past 30 years.
I am based in Florence, Italy.
And apart from writing historical fiction and gardening,
I have one lifelong fascination.
And I am pretty certain that, by now, you know exactly what that fascination is.
It's calcium hydroxide.
So why am I so fascinated with this material?
Well, it is an old material created by mankind
to build mankind as we know it today.
And it's a material that's on the verge of extinction.
It's a material that is dying before our eyes.
So, what is calcium hydroxide?
Well, in very simple terms, it's the result of deconstructing a stone,
and reconstructing that same stone, in a different shape or form.
It's an extremely ancient technology
that has been developed using a very modern concept
and that concept is reverse engineering,
or what we called, in the field of conservation,
experimental archaeology.
And one of the purposes, for the development of lime,
was to do something very intriguing.
To render that which is intangible beauty,
into something extremely tangible, a stone.
Now what I would like to do, is to explain to you,
the reverse engineering of this fascinating material.
But in order to do so,
I need you all, to use your imagination.
I'd like you all to draw a circle in your mind.
And I want you to put a mountain on top of that circle.
I'm going to take you from that mountain on a journey round the circle.
And lots of very exciting things are going to happen.
So if you're all ready,
if you fall on your circle, you've all got your mountain,
we can begin.
I want you to imagine
that your mountain has stones high in calcium carbonate
you're going to fill a truckload with these stones
and now you're going to drive them down your circle
and you're going to stop in the first quarter.
You're going to put your stones inside a kiln,
you're going to fire up the kiln to nine hundred and sixty degrees Celsius.
And two things are going to happen.
The water content and the CO2 are going to disappear from the stone
and a chemical reaction is going to take place
whereby the calcium carbonate is not going to turn
into material known as calcium oxide.
Now, calcium oxide is a fantastic stone.
It is strong. It is noble.
It has a brilliant whiting color, it is thirsty of water.
And if you touch it with your bare hands, it will burn you just like fire.
I want you now to move your stones from the kiln down your imaginary circle
and you're going to stop on the bottom section.
You're going to put your stones inside huge vats of water.
And now you're going to witness
one of the most fantastic chemical reactions,
created by Mother Nature.
It's a thermal reaction.
What you're going to see is your big, strong, noble stone
decompose in front of you.
It's going to turn into a soft mushy paste.
Very similar to cottage cheese.
The thermal reaction is such
that the water is now boiling and bubbling and steaming
and it's spitting everywhere.
And if that water spits on you,
it is going to burn you just like fire.
What you are witnessing is the second chemical reaction,
where a calcium oxide is now turning into calcium hydroxide.
It's turning into lime.
You're now going to move your calcium hydroxide
from the vats of water
and you're going to move up your circle
and you're going to stop at the final quarter.
And this is the moment.
This is the moment where the magic and the alchemy takes place.
This is the moment when human creativity collides with technology
and produces an artifact
of impressive beauty and amazing durability.
This is the moment when you, now a wall painter,
standing on a scaffolding,
you've received your calcium hydroxide.
You're going to mix it with sand and make mortar.
You're going to plaster the wall.
And why your mortar is still fresh?
You're going to mix your pigments only with water
and you're going to begin to paint that wall.
And as you are painting right before your eyes,
a third, and final, chemical reaction is taking place.
The calcium hydroxide inside the mortar is changing yet again.
Water is evaporating from the mortar now, and CO2 is being introduced.
And your calcium hydroxide is now heading back to that mountain.
Your carts and hydroxide is turning into stone
your calcium hydroxide is becoming calcium carbonate yet again.
But not only is the calcium hydroxide turning back into stone.
The pigments you've applied on that mortar:
those too are mineralizing,
those too are going up to the mountain,
those too are becoming stone.
From a chemical point of view, there's no difference whatsoever
between the stone you originally took from the mountain
and what you've now produced.
But from a visual point of view -
oh, from a visual point of view the difference is enormous.
You have not just produced a stone.
You've produced an artifact
of wondrous splendor, of amazing durability
and with colors that will sing throughout the centuries.
You have produced this.
The Raffaello rooms in the Vatican.
You have produced this.
Masaccio in Florence.
You have produced this, the Sistine Chapel.
One of the most magnificent wall paintings created in the western world.
What I've just described to you is a painting technique
that developed in Italy during the early Renaissance
and it's known as the bonfresco.
The good fresco.
This is a painting technique
that we conservators and academics have studied quite a lot
and we understand very well how the mechanisms work.
Nevertheless, our ancestors, throughout history and throughout time,
have implemented lime technology in a myriad of ways
and with dozens and dozens of technical variations
of which we today do not know much.
It is my belief that myself, as a conservator
and many of my colleagues and many of the professionals
that work in the field with us -
I'm talking about the art historians, the geologists, the architects,
the engineers, archaeologists, scientists.
None of us have fully understood just how sophisticated our ancestors were
when implementing lime technology on ancient wall paintings.
And the proof of that lies in the fact
that today in 2018,
in this world of heights in technology and knowledge,
that we live in,
there isn't a single person capable of replicating
from a technical, physical, chemical and structural point of view
some of our most marvellous wall paintings.
I'm talking about the wall paintings that we have in Egypt,
or the wall paintings in India,
or the fantastic examples in Southeast Asia,
let alone the marvels in Latin America.
And the reason why there isn't anybody
that knows how to technically replicate these wall paintings
is because we simply do not know how they were painted.
We have lost a piece of history.
We have lost a piece of knowledge.
And it is precisely because we risk losing knowledge
that I decided to become a conservator and have dedicated my life
to the preservation, conservation and restoration of wall paintings
and to the study of lime.
In preserving the legacy of ancient civilizations,
I know that I am preserving culture.
And culture is the foundation on which civilizations grow and evolve.
Culture is nothing else than a legacy of knowledge
left to us by our ancestors.
And it is our duty,
not only to use that knowledge to better ourselves,
but to preserve it for the benefit of future generations.
Remember the cycle of lime.
Let me put it to you this way.
Culture is the oldest meme on planet Earth.
An ancient art works is the technology used to transmit that meme.
If there's one thing I've learned in my career, as an art conservator
and in studying the structure of artworks
is that human evolution is not a progressive line,
that moves upwards and forwards irregardless of social awareness.
Quite the contrary.
Human evolution is like a spiral
that can move upwards or collapse downwards
according to our own personal choices,
which is why you, all of you,
must not allow the past to be erased.
We cannot afford to forget.
We simply cannot afford to forget our past, our legacy and our ancestors.
So what's next?
What can we, the conservatives working in the field, do
to save for technology as ancient as lime technology?
Well, baby steps are beginning to take place
in the form of a project
promoted by the Tokyo National Research Institute of Cultural Properties.
And thanks to the very hard work of the conservator Mr Yoshifumi Maekawa,
who, together with a group
of international wall painting conservators
has begun to gather data, on a global level,
regarding ancient lime-based wall paintings.
Our ultimate aim is to do exactly what our ancestors did.
Reverse engineer ancient wall paintings,
in order to understand how they were executed.
This information, for us conservators, is vital.
If we want to preserve ancient wall paintings
and guarantee that they will still be standing there,
for future generations to benefit from,
again, I'd ask you to remember the cycle of lime.
Some of you might be wondering if you can contribute to our quest,
to save the ancient technology of lime.
And you can.
And you can do so in very, very easy ways.
For example,
the next time you decide you want to paint your home,
opt for lime-based paints instead of synthetic ones.
Are you a gardener? Fertilize with lime.
Are you a dentist? Embrace calcium carbonate technology.
Are you a tuber, that likes slaking lime in your backyard?
Continue posting your videos and divulging to the public in general
the many, many benefits of this multifaceted material.
Now are you an artist?
Why don't you challenge yourself with a painting technique
which is almost as ancient as humanity itself,
and learn how to paint affresco,
the same painting technique
that fascinated and mystified Michelangelo himself?
But most importantly,
if you're involved in the building industry,
I'd ask you to please embrace the highly ecological material
that calcium hydroxide is
and if you already have embraced it,
please continue promoting
a material that history has proven
to be both sustainable and extremely durable.
And to prove that,
we have artifacts made out of calcium hydroxide
that are still standing today and that were built in 7500 B.C.
But finally, if there's one thing
I'd like you to keep close to your hearts,
one thing I'd like you to do at some points of your life,
is this.
Wherever you are in the world,
the next time you enter an ancient building
that houses an old wall painting
and you find yourself marvelling at the beauty before you,
ask yourself one question.
What is it that ancestors wanted us to marvel at?
Was it the beauty of what they painted, or was it the beauty of what they knew?
I'd like to dedicate this talk
to a man whose academic courage has greatly inspired me
and I hope will inspire you too.
I'm talking about the author and journalist Graham Hancock.
And I'd like to do it
by dedicating a quote from the book "The Restorer".
And the quote is this:
"Time is nothing else than a spiral
that progresses and recedes according to the whim of life.
We, humanity, are the mere mortals that pedal that spiral."
Thank you very much for your attention.
(Applause)