Art Materials of the Renaissance

Paint:

One of the big questions in renaissance painting was, which is more important, draughtsmanship (drawing) or colour? Florentine artists stressed draughtsmanship, and Venetians favoured colour. Why? Well, Florentines favoured fresco paintings in their churches and palaces. With fresco, the paint dries so quickly that the drawing must be planned in detail before hand. Then, it's quickly painted in sections, one or two colours at a time.

Venetians gave up on frescoes because their wet, humid weather ruined them quickly. The Venetians turned to oil paint, which is more resilient (odolný) to humidity. Oil paint also has other advantages. If you look at Giovanni Bellini's portrait of Mary & Child, you'll see that the colours glow because of glazing. Glazing has different meanings, depending on what kind of art your making. In painting, glazing is when you create many thin layers of transparent (priehľadný) colour. The effect is often glossy (lesklý), like glass, and is perfect for blending (miešanie). With oil paint, some colours are transparent and some are opaque (nepriehľadný), so you have a choice when to glaze and when to completely cover what's underneath. This wasn't possible with fresco or egg tempera paints, which are all opaque.

Oil paints also dry slowly, over a course of hours or even days, giving artists the freedom to work slowly, in a relaxed way, and to change the composition as they work. Fresco and egg tempera are both fast drying, and prone to cracking (praskanie). For these reasons oil became popular throughout Europe, soon being the standard paint in all great academic works, all the way up to the modern era. 

Marble (Mramor)

The methods we use today in marble carving are the same as they were thousands of years ago. The process is:

1. Roughing (hrubé opracovanie)
2. Modelling
3. Refining the Stone
4. Finishing the Surface

First, to rough out your sculpture, draw where you're going to cut with charcoal. You start with a point chisel (rovné dláto), which bursts the stone away quickly.

You model with a tooth chisel, (zubaté dláto) which looks like a comb. It models form with greater delicacy than the point chisel, while still removing stone quickly. There are different sizes for smaller details.

You can refine form with special spinning tools that carve in crevices (pukliny) that a chisel can't reach. You finish the surface with rasps (rašpľa), brushes, and files (pilníky), that polish surfaces to a high gloss.

Bronze

Bronze sculpture was first developed in ancient Mesopotamia. The Greeks get the credit for scaling up the process to life-size human figures. It's a complicated process involving techniques that were lost in the west and relearned during the renaissance. I think the first Italian artist to make a life-size bronze sculpture was Arnolfo di Cambio (1240-1310), with his seated St. Peter, made for St. Peter's Cathedral in the Vatican. But Donatello (1386-1466) made the first free-standing, life size nude in bronze, his statue of David, now on display in Florence.

Bronze sculptures are cast, following the lost wax technique. The process can be direct or indirect. In each case, the sculpture is hollow, to save on bronze, an expensive material. Direct casting consists of four steps:

1. Modelling

2. Casting

3. Chasing

4. Finishing

The sculpture begins as a wax model, usually beeswax. It typically has an iron wire (drôtený) frame, called an armature (armatúra) that gives the sculpture strength. Modelling is simply the process of adding wet clay and/or wax to this armature to build and sculpt a figure. If the work uses clay, it's only for the core (jadro) of the work, and wax is modelled on top of it. The hands don't need a core. Once the wax is carefully sculpted, the figure looks like a finished sculpture - but it isn't.

The next stage is to prepare it for casting. Iron core pins and wax sprues (vtokový kanál) are inserted at important points in the sculpture. The core pins hold the clay core in place after the wax melts away. The wax sprues lead up to a wax pouring cup. All these sprues will melt along with the rest of the wax, creating channels for the bronze to flow through later in the process. Some of the sprues form vents that will allow hot air to escape.

A layer of clay, called an investment (forma), is painted over the wax, and will serve as a mould (forma). The investment is then turned upside down and heated to melt all the wax, which then pores out. One curious fact about the process is that the sprues are all pointing up at this stage, so that the wax must somehow flow up before flowing out.

Now that the wax is out, the investment is turned right-side up and buried in sand, to protect workers in case it explodes during the next stage - which is to pour in molten bronze. This happens in a workshop called a foundry. People who work there are called founders. The bronze is placed in a crucible (topiaca nádoba), a kind of bowl, and melted in a furnace (pec), at about 2000 ºF (1093 ºC). Impurities called slag (kal) is scraped off the top of the molten bronze and thrown away. The crucible is then taken out of the furnace and poured gently into the investment.

After the investment cools and the bronze hardens, the investment is broken down with hammers to reveal the sculpture inside. All the sprues are now bronze and have to be chiselled away (osekaný dlátom) in a process called chasing (tepanie). The core pins are also removed with pliars (kombinačky). All the soot (sadza) of the sculpture must be rubbed away. Imperfections must be fixed, and any holes from the sprues must be plugged (zazátkovaný) with bronze. Details are refined with a variety of tools. The sculpture is then polished (vyleštené) to a shine, and finished with a patina to protect the surface. There are many kinds of patinas, using materials such as acid, lacquer (lak), or wax, that can change the colour and lustre (lesk) of the work. Long exposure to outdoor weather can ruin a patina.

 

With indirect casting, the wax model is cut into pieces and cast separately in plaster. The moulds are then filled again with melted wax, which coats the surface of the mould, creating a hollow version of the piece. These hollow wax pieces are joined back together creating a hollow wax figure. This hollow figure is then filled with "core material" a mixture of sand, clay, and plaster. Iron pins are inserted before this core solidifies to help hold it in place. Solid wax sprues are attached, and the sculpture is encased in an investment, just like with direct casting. The rest of the process follows identically to direct casting. The advantage of indirect casting is that you still have those plaster moulds, which are reusable, so you can make hundreds of copies of your work.