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Tuesday, March 13, 2012

Art course notes /2 (Appunti del corso di disegno e pittura /2)

Sizing

Before painting, the canvas needs to be sized by applying a protective coat in order to:
- stretch the canvas
- improve the adhesion of pigments
- enhance the color brightness
- protect the canvas from the natural acids in oil paints
- make the canvas smooth and easier to paint on.
Canvases can be sized by applying water soluble cementite (simple, quick and inexpensive) or rabbit glue+Bolognese chalk (classic method, more expensive and time-consuming).

Sizing with cementite.
Cementite can be bought in hardware stores.
Mix with water and use a large brush to paint several layers, by alternating horizontal and vertical strokes, taking care to not stop before the canvas' edge.
It is possible to add pigments (gouache or acrylics, no oils) to the sizing for special effects, or sand, to create texture.

Below, my first attempt at an oil painting (work in progress). Sand from the beach was added to the cementite, as well as some gouache, to obtain a textured and slightly coloured surface.
My teacher told me I should make as many mistakes as possible, to learn better, and I did it :) Fortunately, oils are quite forgiving (on the right, mistakes fixed).

WIP - first painting in oils - mistakes WIP - first painting in oils - better

L'imprimitura

Prima di dipingere, la tela va preparata. Tale preparazione si chiama imprimitura e serve a:
- tendere la tela
- favorire la tenuta dei pigmenti
- esaltare la brillantezza dei colori
- proteggere la tela dagli acidi naturalmente contenuti nei colori a olio
- facilitare l'esecuzione.

Puo' essere effettuata con cementite ad acqua (semplice, veloce ed economica) o con colla di coniglio e gesso di Bologna (metodo classico).

Metodo con cementite.
La cementite si acquista dal ferramenta.
Si allunga con acqua fino ad ottenere una pastella fluida e si passa sulla tela con un pennello in diversi strati, sia in senso orizzontale che in senso verticale, avendo cura di non fermarsi prima dei bordi.
Per ottenere effetti particolari si può aggiungere alla cementite del pigmento (tempera o acrilico, non olio perché non si miscelerebbe con l'acqua) oppure della sabbia per creare texture.
E' quanto è stato fatto nell'esempio riportato nella foto, il mio primo dipinto ad olio (ancora in progress, naturalmente). All'imprimitura sono stati aggiunti un po' di tempera e della sabbia raccolta sulla spiaggia di Pescara.
Il mio insegnante mi ha "ordinato" di commettere più errori possibile, in modo da imparare meglio, e l'ho preso in parola :) Ma c'è da dire che i colori ad olio sono clementi e permettono di correggersi...
(v. foto a destra)

5 comments:

  1. Those art notes of yours are truly fascinating, even for me.

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  2. Back in the long-old days, when I was taking art courses, I used to love building canvas stretchers, stretching the canvas, and gessoing it. I loved painting too, but those other things were different--meditative, perhaps. Great ideas of adding texture....

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  3. You really are jumping into art full force. I've been painting (in my off time) all my life; I've yet to stretch and gesso my own canvas! Brave gal you; lazy gal me. Upon retirement, blogging daily is how I made art a full time obsession. I'm glad I found you. I'll follow your progress.

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  4. It's me again. I wanted to thank you for becoming a follower. I tried to contact you via e-mail, which Blogger says I can, but I kept getting asked if I'd like to follow my own blog, which I do closely. So here I am again. I have some words of advice: don't let process get in the way of you expressing you however. After two years blogging and seeing all the talented people around, I have. And it's just dawned on me that that's a snag that will tie me up again as it did years ago when I went to art school. Forget about the "shoulds" and just loosen up. Welcome.

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  5. Che belli questi tuoi appunti del corso... li leggerò con grande attenzione! Un abbraccio!

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