Uncovering the Secrets of White Slip Ware

The Late Bronze Age in Cyprus saw the island transform into a vital hub of trade and cultural exchange in the Mediterranean. One of the most iconic and widely traded pottery styles from this period was White Slip ware - elegant bowls, jugs and tankards with a characteristic creamy white slip coating. A fascinating new study by Braden Cordivari and Marie-Claude Boileau [1] provides an unprecedented look into how ancient Cypriot potters created these masterpieces, tracing the production process from clay sourcing to firing. By examining White Slip vessels from the Bamboula necropolis near Kourion in southwestern Cyprus, the researchers also shed light on how manufacturing practices evolved over a 200-year period from around 1600-1400 BCE. Let's delve into the details of how White Slip ware was made and what changed from its early beginnings to later florescence.

The White Slip Production Process

Cypriot potters had access to excellent raw materials thanks to the island's unique geology. Most of the White Slip vessels analyzed were made from mafic clays derived from the igneous rocks of the Troodos Mountains in central Cyprus. These clays contained the perfect ingredients - altered clinopyroxenes, amphiboles, and feldspars - to produce durable but attractive pottery. Potters appear to have used these clays without much modification, as the angular, poorly-sorted mineral inclusions indicate the clays came straight from weathered source deposits rather than being refined.

Vessels were primarily built using two techniques - slab molding for the lower body and coil building for the upper body and rims. X-ray images of bowls show compression features and tears that point to potters pressing slabs of clay into or over molds to create the hemispheric shape. Horizontal voids near the rims are telltale signs of coils added to increase the height. Beating and paddle-and-anvil work was then used to thin the walls, attach handles and lugs, and achieve the final refined shape. Feet, where present, were shaped from coils.

The distinctive white slip that gives the ware its name was applied before firing. Two main slip recipes were used. The most common was rich in chlorite, a magnesium clay mineral, along with quartz. A rarer type, found mainly on earlier White Slip I vessels, contained only quartz, while some also featured chert fragments. The thickness of the slip layers (up to 0.48mm) and their somewhat granular texture suggests the slip was more of a clay-water mixture applied by dipping or heavy brushing than a fine-grained slurry.

Once slipped, the still-leather-hard vessels were burnished to a shine and painted with characteristic abstract or pictorial motifs. Paint recipes also varied, with earlier White Slip I using mainly iron-rich pigments, while later White Slip II incorporated manganese, likely to achieve darker and more stable colors.

The final step was firing the finished vessels. FTIR spectra and electron microscopy show that firing temperatures ranged from around 800°C to over 1000°C, with the higher end likely requiring kilns to maintain such heat. Potters employed a variety of firing practices. Some vessels were fired in a reducing atmosphere to create gray cores before a final oxidizing soak that resulted in light-colored surfaces. Others were once-fired in a fully oxidizing environment. Interestingly, the slip appears to have often been applied and fired separately from the underlying clay body, as it shows consistently lower temperatures, suggesting a double-firing process in many cases.

Changes Over Time

While the general production sequence for White Slip ware remained consistent over the 200 years studied, Cordivari and Boileau identified some notable changes in materials and practices as the style evolved from White Slip I to White Slip II.

In terms of clay recipes, White Slip I vessels show a consistent reliance on one petrofabric (clay type), used over a long period and across multiple sites. White Slip II, in contrast, displays much greater variability, with potters using a range of new mafic clay mixes, while still continuing to use some White Slip I recipes. This diversification of materials in later White Slip II parallels its greater scale of production and distribution.

Some forming techniques may also have changed over time. While both White Slip I and II employed slab molding and coil building, the use of coils to form rims appears to be an innovation associated with later White Slip II. The application of thick chlorite-rich slips also seems to be a later development, with earlier White Slip I slips being primarily quartz.

Firing practices also show development over time. Cordivari and Boileau's FTIR data suggest that firing temperatures increased in the LC IB period (1550-1450 BCE) for both White Slip I and II compared to the preceding LC IA:2 (1650-1550 BCE). White Slip II also appears to be more consistently high-fired than White Slip I, potentially indicating greater control over the firing process and the more frequent use of kilns.

The pigments used for painted decoration clearly distinguish the two phases. White Slip I mainly used iron-based colors that could fire to reds, oranges and yellows. In White Slip II, these were replaced by iron-manganese pigments that created dark browns and blacks. This shift, paralleled in the use of manganese-based paints on other contemporary wares, likely reflects the potters' desire for bolder, higher-contrast designs.

Conclusion

Cordivari and Boileau's study provides a fascinating window into the sophistication of the ancient ceramics industry in Late Bronze Age Cyprus. Using an impressive array of analytical techniques, from microscopic petrography to spectroscopy and X-radiography, the researchers reconstructed in detail how White Slip ware vessels were made. Their work reveals that the iconic White Slip style was not monolithic, but showed significant diversity in materials and practices, especially in its later White Slip II phase.

We can envision communities of highly skilled potters, clustered near clay sources in the foothills of the Troodos Mountains, engaging in friendly competition as they developed the signature look of White Slip bowls, jugs and kraters. Over time, they improved their practices, from more efficient forming and finishing to higher firing temperatures, and created a wider range of slips and paints. Thanks to their expertise, White Slip ware was traded far and wide, spreading Cypriot ceramic style across the Bronze Age Mediterranean world.

Perhaps most intriguingly, the authors show how tracing these evolving techniques can reveal economic and social connections between these inland production centers and coastal hubs like Bamboula. The diverse White Slip vessels deposited in Bamboula's tombs are tangible evidence of long-lived trade relationships between the agricultural lowlands and copper-rich highlands at a time when Cyprus was a vital crossroads. As White Slip ware changed from phase I to II, so too did the webs of exchange that sustained the island's increasingly complex urban centers and fueled its commercial and cultural contacts with the wider world. Cordivari and Boileau's innovative study demonstrates how pottery, so abundant yet often overlooked, can speak volumes about the lives of ancient artisans and the societies they belonged to when examined with the powerful tools of archaeological science.