The Chemistry of Buon Fresco Painting

Beranda » Berita Terbaru » The Chemistry of Buon Fresco Painting

Cetak Ramah dan PDF

Oleh Jim Hingst
When someone mentions fresco painting, what
always comes to my mind is Michelangelo painting in the Sistine Chapel on wet
plaster. Of course, that’s not the only type of fresco painting, but it is
arguably the purest and the most durable form.

Sistine Chapel ceiling by Michelangelo.
Michelangelo
[CC BY-SA 3.0 
(https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia
Commons. Photograph by Antoine Taveneaux Taken on 14 June 2014.
Frescos painted in this manner two thousand
year ago still retain their color. The photo below depicts a fresco from the
ancient city of Pompeii, which was buried under volcanic ash in 79 AD during
the eruption of Mount Vesuvius .  
Painting on wet plaster is known as buon
fresco. Buon means true or genuine and fresco means wet. In other words, buon
fresco means  true fresco. What makes
this form of painting so durable is that the pigment is absorbed into the
plester.  Another type of fresco painting
is called fresco secco (dry), in which artist paints on dry plaster with
pigment in lime water.

Fresco showing fruit bowl, jar of wine, jar
of raisins, from the House of Julia Felix in Pompeii, Naples National
Museum Arkeologi.
(Ini
work is in the public domain in its country of origin and other countries and
areas where the copyright term is the author's life plus 100 years or less.)
What is so fascinating to me is the chemistry
of buon fresco painting. In this unique process calcium carbonate (CaCO3) in
the form of limestone is heated to 1652°F or 900°C. In this process, which is
known as calcination, the calcium carbonate is converted to calcium oxide (CaO)
called quicklime and carbon dioxide (CO2).

The term calcination comes from the Latin
word “calcinare”, which means to burn lime. In spite of that meaning, the
process of calcining is also used in the creation of pigments. For example, when raw
umber is subjected to calcination, it becomes burnt umber.
CaCO3 + heat → CaO + CO2.
The calcium oxide is highly alkaline, which
makes it very corrosive. It is so corrosive that it can actually cause a
chemical burn on your skin. Next, water and calcium oxide are mixed to produce
calcium hydroxide (Ca(OH)2), which is called slake lime.  This chemical reaction releases a tremendous
jumlah panas.
CaO + H2O → Ca(OH)2 +
panas.
The slake lime is mixed with sand to form the
plaster.  Instead of using sand, Michelangelo did things a little differently. He used volcanic ash, called “pozzolana”, in the mixture. 
The pozzolana reacts with
the calcium hydroxide to form a harder plaster.  
 


CATATAN: What is also interesting is that the Romans also mixed volcanic ash with quicklime and water to create
what we today call “super concrete”, which outlasts modern concrete. As the
mixture cures, crystals form, filling any microscopic spaces and reinforcing
strukturnya. 



In fresco painting, the artist first applies a layer of plaster, which is allowed to dry
for a couple of days. The underlying later of dry plaster is called the arriccio.
Next, a layer of the wet plaster, called the “intonaco”,  is applied to the wall or ceiling to be
decorated.

The artist first pounces the pattern of the preparatory drawing, called the “cartoon”, onto the wet plaster, using the same technique that the old sign
painters used. The artist then paints on the plaster using a simple mixture of
water and ground pigment. 



Michelangelo used a very
limited palette of approximately seven colors. These were primarily earth colors, such as carbon black, ochres, sienna and terre verte. For blue, he used lapis lazuli. 
Because the plaster is
highly alkaline, not all pigments are compatible with it and will fade in time.



The wet plaster dries in about  six to eight hours, depending on the ambient temperature and humidity. That doesn’t
give the artist much working time. For this reason, the artist only applies
enough plaster that he is capable of painting in one day. The term that is used
for this day’s work is “giornata”.

The wet plaster combines with the carbon
dioxide in the air as it cools. As the plaster cures, the water evaporates. What remains
is calcium carbonate, the same material that started this procedure. The
chemical processes have come full circle.
Ca(OH)2 + CO2 → CaCO3 +
H2O
The paintings of Michelangelo have endured
for more than 500 years because the pigment is encased between the molecules of
calcium carbonate of the plaster.



Apakah Anda Memiliki Pertanyaan atau Komentar?





BACAAN YANG DISARANKAN


Technique of Fresco Painting Paperback – January, 2000

by Gardner Hale

Instructions For The Practice Of Fresco Painting (1843) Paperback  by W. Winsor (Editor), H. C. Newton (Editor




Tentang Jim Hingst: Menandatangani otoritas bisnis pada bungkus kendaraan, grafis vinil, sablon, pemasaran, penjualan, daun emas, ukiran kayu, dan lukisan. 

Setelah Setelah empat belas tahun menjadi Manajer Pengembangan Bisnis di RTape, Jim Hingst pensiun. Ia terlibat dalam banyak aspek bisnis perusahaan, termasuk pemasaran, penjualan, pengembangan produk, dan layanan teknis.

Hingst memulai kariernya 42 tahun lalu di bidang seni grafis dengan membuat dan memproduksi materi iklan dan promosi untuk produsen peralatan uji besar. Bekerja untuk percetakan offset, percetakan layar format besar, produsen film vinil, dan perusahaan pita aplikasi, pengalamannya meliputi estimasi, perencanaan produksi, pembelian dan produksi seni, serta penjualan dan pemasaran. Dalam kapasitasnya sebagai tenaga penjual, Hingst diakui dengan berbagai penghargaan atas prestasi penjualan.

Dengan mengandalkan pengalamannya dalam produksi dan sebagai subkontraktor pemasangan grafis, Hingst memberikan saran praktis kepada industri, dengan menerbitkan lebih dari 150 artikel untuk berbagai publikasi, seperti Signs Canada, SignCraft, Signs of the Times, Screen Printing, Sign and Digital Graphics, dan Sign Builder Illustrated. Ia juga mengunggah lebih dari 500 cerita di blognya (hingstssignpost.blogspot.com). Pada tahun 2007, buku Hingst, Vinyl Sign Techniques, diterbitkan.  Teknik Tanda Vinyl tersedia di distributor perlengkapan tanda dan di Amazon. 

Hak cipta © Jim Hingst 2018 

Baca Selengkapnya

Tulisan tidak ditemukan

Maaf, tidak ada postingan lain yang berhubungan dengan artikel ini.

Tinggalkan Balasan

Alamat email Anda tidak akan dipublikasikan. Bidang yang harus diisi ditandai *

Penyedia Baru
binola

Broker yang
Lebih dari 2 juta bisnis
Lihat 10 Pialang Teratas

permainan

Permainan online
Lebih dari 2 juta bisnis
Lihat 10 Game Online Gratis Teratas

Game baru
Kebohongan P

$59.99 Edisi standar
28% Hemat Diskon
Lihat 10 Game Penyedia Teratas

KEPOMPONG

$24.99 Edisi standar
28% Hemat Diskon
Lihat 10 Game Penyedia Teratas

Penawaran Baru
Komisi hingga $1850 untuk pengguna aktif program afiliasi Oleh Exness

Poin Teratas © Hak Cipta 2023 | Oleh Topoin.com Media LLC.
Topoin.info adalah situs review produk, bonus, penawaran, penyedia layanan bisnis dan perusahaan terbaik dan terpercaya sepanjang masa.

Temukan lebih banyak dari Poin Teratas

Berlangganan sekarang untuk terus membaca dan mendapatkan akses ke arsip lengkap.

lanjutkan membaca