Raw Materials and Semiproducts

Lead carbonate (lead white)

The most numerous in the ship’s lower deck are 50 cm high casks filled with cones of white lead (lead carbonate, cerussite, sometimes in combination of base lead carbonate, hydro cerussite), wrapped in textile and straw. All cones have an average height of 5.5 cm, a diameter at the top of 6.3 cm, and a diameter at the bottom of 2.6 cm, while average weight is 390 g.

The external surface of the lead white ingot is usually coloured, due to the contact of lead with the other substances which were present in the cargo. The thickness of alteration layer can vary, from 2 mm to 15 mm and sometimes even more, depending upon how long and under what condition the cone was in contact with the substance which caused the reaction.

Lead white was a favoured white colourant since Antiquity; its excellent covering capabilities and its ability to mix with other colours to create different hues were the reasons why it remained in intensive use until the twentieth century. The use of lead white was particularly intensive during the Early Modern period. It proved to be a favourable material applied to paintings after the introduction of the painting with oil technique.

Lead (II, IV) oxide (minium)

At the Gnalić site, red lead has been found in only two lumps. The lumps are irregularly shaped, of average length 9 cm, height 5 cm, and width 6 cm. The average weight of each piece is 800 grams. The packaging method is unknown, since the lumps were found in the sediment on the southern part of the site, in the layer together with scattered cones of lead white.

Lead (II, IV) oxide is a bright orange pigment known from both archaeological sites and written sources since Classical Antiquity, today known by common names lead tetraoxide, red lead and minium. During the Middle Ages, minium was often used in monasteries for decoration of manuscripts. It was also used to paint furniture, with the purpose of both decoration and protection. It was an indispensable ingredient in making pottery glaze and often an addition in the production of glass.

Mercury (II) sulphide (cinnabar)

The finds from the Gnalić shipwreck include two forms of mercury sulphide. The bell-shaped form has a weight from 80 to 100 kg. All the dimensions of the entirely preserved artefacts are consistent. The diameter of the widest part and the height is 27 cm. The bottom diameter is 21.5 cm, and there is a conical indentation with a funnel-shaped channel going through the body of an approximate diameter of 1.8 cm. In total, fourteen bell-shaped mercury sulphide ingots were recovered.

The second form of mercury sulphide found, is in the shape of lumps, with a visible needle-like internal structure. The lumps vary in size and weight, from small fragments found in sediments, to lumps of pointed and rectangular-like shape of weight of almost 1 kg. It is not determined yet whether these two types of mercury sulphide were produced by the same method into a different form, or if their methods of production were different.

Mercury sulphide can be found in Renaissance paintings,very often mixed with lead white to obtain flesh tone. A madder glaze was sometimes added on top to obtain a glittery finish. Historical sources provide recipes of how to prepare mercury sulphide for miniature painting, but it was also highly preferred in wall painting and furniture decorations. The qualities of mercury sulphide are evidently its great covering power, stability, and compatibility with other pigments, which allowed painters to combine it with other materials.

Antimony (III) sulphide (stibnite)

Since the first Gnalić excavation campaign in 1967, three lumps of stibnite have been found. All have irregular shape, metallic lustre and bladed crystals. It is unknown what type of packaging existed, or where the fragments were originally located on the ship. Since only a small amount has been recovered, it is possible that the pieces were originally located on the upper decks, ending up, after the disintegration of the ship, covered with sediment in the area of the keel.

When used in painting, antimony (III) sulphide or stibnite was finely ground to keep a dark grey colour. It was recognized in numerous examples in the polychrome of Gothic sculpture in Germany. Artisans in Venice found the compound antimony sulphide indispensable in the production of objects typical for the Venetian markets. They had gained knowledge of mixing a certain percentage of antimony with other metals to create alloys of improved properties. For example, mixing antimony sulphide into the alloys used to cast church bells improved the quality of the sound. It was also used in the pewter alloys employed to produce household vessels. Antimony sulphide was also an indispensable component in pottery production in North Italy.

Arsenic sulphide-based material (realgar and pararealgar)

Arsenic sulphides encompass orpiment (As₂S₃) and realgar (AsS), which appear jointly in nature, and they could appear together in late Renaissance Venice inventories of the colour seller shops. The inventory of Domenico da Gardignano from 1534 mentions oropimento and rexegal, while Jacopo de’Benedetti’s inventory from 1594 lists oropimento and oropimento rosso. However, only realgar has been attested at the Gnalić shipwreck site. It was found in the form of bright yellow powder, and is often associated with the casks containing lead white ingots. However, as one of its main characteristics is its solubility in water, it is difficult to study its real position in the wooden containers.

Arsenic sulphides were commonly used on frescos and oil paintings. These intensive colours, which range from yellow to orange and red, were in use since the end of the fifteenth century by masters of the Venetian school, and became signature hues of the late Renaissance.

Besides decoration, arsenic sulphides were used in cosmetic purposes, especially for the purpose of hair removal when mixed with lye. There was a belief that the arsenic compound would act as a remedy against the plague if it was worn over the heart. It was also believed that the fumes of arsenic could cure asthma, as well as coughs that are a symptom of some diseases.

Iron oxide (hematite)

Red ochre from the cargo of Gagliana grossa was preserved as a fine powder, composed of hematite, alunite, quartz, and clay minerals. It was stored in oval barrels of 80 to 90 cm height, with a lid diameter from 60 to 65 cm. All the barrels were kept in the ship’s hold, surrounded by the casks of lead white ingots and arsenic sulphides. There were at least six large oval barrels filled with red ochre.

Throughout history, red ochre was often used as a painting material due to its great covering abilities, permanence, and compatibility with other pigments. Considering the Renaissance, it has been mostly attested on frescos. Presumably, as it was relatively common and did not require complex refining techniques, red ochre must have been available at a low price.

There are very scarce sources which can be taken as evidence for trade with red ochre. Nevertheless, it was known there was no need to import it to Venice, as it was readily available in the vicinity.

Elementary mercury (quicksilver)

On the Gnalić shipwreck site, mercury has been found in the liquid state all over the site. The total recovered amount is over 50 kg, which is equivalent to approximately 4 litres of mercury. Mercury was collected with the help of medical syringes and glass jars. The original method of its packaging is unknown. Having mercury freely running at the site raised the question whether the mercury was an individual cargo item, or perhaps the drops might have separated and fallen from other merchandise present in the hold. The drops of mercury could have originally belonged to the reflective surface of mirrors, which were composed of a tin-mercury amalgam.

Even though mercury is a hazardous substance, it had wide use in Renaissance everyday life, as a remedy and as a material required in manufactures and arts. During the sixteenth century, mercury was widely used because of its property to create an amalgam with other metals. In contact with tin sheets, it created a silvery reflective layer used in the manufacture of mirrors. Further, mercury had an indispensable role in gilding and silvering decorative techniques. It has been used for application of precious metals on the surfaces of metal objects.

Lake pigment

The lake pigment is preserved in the shape of balls, with an approximate diameter of 1.5 cm and an average weight of 1.75 g. Approximately 30 balls were accumulated at the same spot, in the vicinity of the metal pins, glass beads, small-size metal buckles and the lead seals used to pack the merchandise, in this case probably textiles. The packaging method is unknown, but was probably a textile or leather bag. The balls of red lake pigment were found in the area which is interpreted as the beginning of the upper deck.

Red lake pigment was prepared from an alunite base, with a sediment of organic dye made of cochineal (carmine), the red madder root (alizarin) and brazilwood (brazilin). Similar to dyes, lakes are made of organic materials. The difference is that the lake pigment is precipitated onto a substrate, which is very often a hydrated alumina. The precipitate is composed of organic materials, mostly insects and plants. Lake pigment can be mixed with a binding medium and applied onto various materials, including canvas, walls, and the surfaces of objects. It has been stated by researchers that the red lakes are a by-product of the textile and silk industry. The red lake pigments could be made directly from insects and plants, but due to economical and aesthetic reasons they were usually manufactured by reusing dyed cloth clippings or shearing of dyed silk.

Tin bars

The semi-products contained in the ship’s cargo consisted also of approximately 1,000 kg of tin ingots, in the form of 1,773 bars with a length of about 63 cm, weighing about 0,56 kg each. Long narrow bars were stamped with the circular inscription "CETO DE STAGNI", in the middle the motif of Venetian lion, and the initials "MC". Tin was not obtained in Venice, but was only melted there. The stamp was used to confirm the quality of the goods. The purity of the tin satisfies the highest quality standards. Tin bars were transported in wooden boxes.

Brass wire, brass rods and steel plates lined with tin

Among the cargo, there were 12 large and 50 small coils of brass wire (1.2 mm diameter), 160 brass rods with triangular cross-section, 60 cm long and weighing 80 kg, and 206 rectangular steel plates lined with tin. Large coils of densely wound thicker brass wire (copper and zinc alloy with a large percentage of lead) were found stacked one on top of the other, in height of about 70 cm. Into the central void small coils of thin brass wire and needles were inserted. The brass cargo probably originated from the Bavarian city of Nuremberg.

Thin plates, with a smooth surface coated with a thin layer of tin, were partially corroded, but still silvery. They measure 55.5 x 25 cm, and they are 0,5–0,6 mm thick.

Brass sheets

Noteworthy in the group of semi-products are two types of sheet brass: 14 sheets, 17 cm wide and 16 cm long, multiply folded and packed four apiece (Germ. Bugmessing), and over 70 rolled sheets, 10-11.5 cm wide and approximately 140 cm long (Germ. Rollmessing). On both types of brass sheets, the manufacturer's mark was found, which resembles the fish bone. They all probably originated from the Bavarian city of Nuremberg.