Only three qualities of gold, its luminous yellow color, ductility, and the fact that it is unalterable, have been enough, not only to choose this material for minting coins, but also for its use in the world of many arts. of civilizations, although today we are going to focus on gold and its application in the decorative arts.

And it is that, since always, gold has been considered a rare material, when more precious, more reserved for worship, associated with eternity, divine power, and of course, ostentation and wealth.

Next, we will explain some of the basic notions of this material, and what is the procedure that the artists followed, to capture it especially in the world of altarpieces.

Gold in altarpiece painting

In the pictorial field, gold, as well as other materials of the style, such as silver or tin, during medieval times, were always used in the form of very fine sheets, which ended up adhering to the surface of the support, efficiently prepared.

And if you have the opportunity to get closer, come closer! And never be left behind, because from afar, those backgrounds are apparently smooth, but if you get closer, you will discover the subtlety of some fine and elegant works, ranging from incised drawings, small repetitive decorations engraved in gold, with the punching technique, to relief ornamentations, made with the same gold, known by the inlay technique.

But, not only the backgrounds, but the nimbus, the mitres, the crowns of many of the characters represented in the various compartments of the altarpieces, are also golden. The clothes, the same, those more precious and elegant also sported golden ornaments, some applied on the layer of color, and others, were achieved, painting the ornaments with a transparent or opaque color on top of the gold, or, sgraffito the superimposed drawing to reveal the gold underneath. And all this was done to imitate both the embroidered motifs and the fabrics with silk threads wound in very fine sheets of gold and silver, so appreciated at that time.

Types of metal sheets

In the Middle Ages, artists only worked when they received specific orders, and it was also the clients who decided what materials to use. In this sense, the painters always bought the most expensive materials, although also depending on the type of commission they had received, and the signed contract, but they never accumulated them, since they were always bought in their fair measure, since only the investment in gold, it was a substantial part of the total cost.

However, to obtain the gilding in panel painting, the painters took into account several qualities of metallic leaves:

• • Gold leaf or gold leaf was the most frequent. Clients, to ensure the quality of the gold, specified in their contracts that it be made of Florence florin, a 24-carat gold coin, and therefore pure gold, widely used in European countries. Western.

Unlike fine gold leaf, which was somewhat thicker and heavier, and therefore more expensive, gold leaf was more likely to be used regularly, being more durable and less vulnerable to surface wear.

• • The broken gold. It was a very fine gold leaf beaten over a silver one, both being soldered. Unlike the previous one, this was a material that cost half the price, as it contained less gold, its color was somewhat paler, and it had to be varnished to prevent corrosion, and even so, over time it tended to blacken.
• • The old silver leaf. Needless to say, it was the most affordable. What was done with this was to varnish it with a yellowish varnish, the corla, to obtain that golden aspect. It was applied above all in irrelevant areas of the altarpiece.

Procedure for applying gold

Only some painters had the help of a specialist in gilding. Once the wooden structure was prepared, with its different layers of plaster and glue, and the painter's drawing to be represented had been sketched, he prepared to make incisions, to delimit the areas that would be painted, from the golden ones.

Once these tasks were carried out, the layers of bol were applied, a very fine ocher-colored clay, which was mixed with a rabbit's tail tempera, in the areas to be gilded, and then proceeded to do so, not without Before passing a brush with water, what it did was regenerate the glue, so that the metal sheets adhered better to the support, which adapted to the surface, with the help of another short-haired brush.

Subsequently, these leaves could be burnished or polished with an agate stone, to obtain a brighter surface, and decorated, engraving small drawings with the help of punches or toothed wheels, depending on the motif to be made. Now, in the event that you want to add decorative motifs in relief (inlay), such as pearls, you drop the plaster or liquid glue on the brush, and this, in turn, on the support. Once dry, the motifs were modeled with scraping irons. Other times, decorations were directly attached, previously obtained by means of molds.

Sometimes, these metal sheets were painted with an opaque color, to later scratch and make the gold appear, creating a golden-polychrome rhythm. Similarly, to achieve transparent effects on gold, colored transparent lacquers were applied with a brush.