One of the most accomplished and sophisticated wares in ancient Egypt is the black-topped pottery that was mainly manufactured during the Amratian (Naqada I) and Gerzean (Naqada II) Periods (4000-3000 BC). This pottery has the distinctive feature of having a polished red body with black on the rim and on the inside. The greatest concern on the black-topped pottery is the chemistry used to produce the black coloring and the firing method, which have engendered much discussion and debate over the years. Based on the scientific investigations, we came to the conclusion that the black color is due to a carbon adsorption caused by the organic materials and the firing under reducing circumstances. The firing method of the black-topped pottery is, however, still in controversy. Hypotheses are generally divided into two interpretations. One is the firing in which the red of the body and the black of the rim are produced simultaneously. The other is the two-step process in which the red-hot vessel is removed from the hearth and placed immediately rim down into organic materials. Although primitive firing methods might have been used by ancient potters, most of the previous experimental firings have been carried out in electric kilns. The purpose of this paper is, therefore, to reproduce black-topped pottery in the primitive way, and to limit the assumptions of its firing method.

Five firings were carried out; 1) bonfire, 2) bonfire in pit, 3) mud-covered bonfire, 4) updraught kiln, 5) two-step production. 1) ~ 4) were operated as one-step processes in which the vessels were placed upside down into the bed of the chaff before firing. The sample pots were made of clay with small amounts of fine sand and organic temper. The surfaces of the samples were coated with the red slip (ferric oxide), and polished with a pebble when half dry.

1) Bonfire: at first, a shallow hole about 10cm in depth was prepared in the ground, and filled with chaff. Samples were placed on the chaff, around which firewood for fuel was set at some distances. After firing, firewood was gradually moved nearer to the samples in order to avoid a fast rise in temperature. The maximum temperature was reached between 700~800°C. Although the carbon adsorption occurred, black stains were observed to remain on the whole outside of the samples. Thus, the bonfire did not easily produce the complete black-topped pottery.

2) Bonfire in pit: a pit (1.5m square and 35cm in depth) was dug in the ground, in the bottom of which firewood and chaff were laid down. Samples placed on the chaff were covered with straw and firewood. Once the firewood was set on fire, the temperature rose rapidly, after 5 minutes it reached 800°C and was kept at that temperature for 10 minutes. The result was the same as with the bonfire method.

3) Mud-covered bonfire: this method of firing is still widely practiced in Eastern Asia, the so-called Unnan style. The samples were placed on a bed of chaff, around which firewood and straw were leaned, and were entirely covered with a layer of mud.

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After 85 minutes from ignition, the temperature inside reached 950°C, then after 170 minutes it reduced to 200°C. As the mud-cover was broken after it had cooled down, the firewood turned out to be charred and the chaff had not been burnt off. The samples were adequately fired, around the mouth of which the carbon adsorption was also achieved. Moreover, the silvery luster between the red and black zone was observed as the same as the ancient black-topped pottery.

4) Updraught kiln: the kiln used in this experiment was a simple one, the interior of which was partitioned by a grid radiating from a central pillar to make a hearth and a firing chamber. The chaff was laid on the fireproof plates set on the grid, and the samples were placed in the chaff. The temperature in the kiln was increased gradually to prevent damage to the samples. 215 minutes after ignition, 800°C was reached, after that, 650~800°C was kept for 60 minutes. The highest temperature, 870°C, was recorded at 220 minutes after the kiln was set on fire. The result was that the samples were baked very well, and the firing itself was proved to be successful. The carbon adsorption was, however, not observed in most samples, because the chaff had been reduced to ashes.

5) Two-step production: at first, the samples were baked in a bonfire. The temperature rose rapidly after ignition, and reached 740°C the highest temperature in about 45 minutes. When the original carbon in the samples was burnt out, the red-hot samples were removed from the hearth and put into the hole filled with chaff. The carbon adsorption was attained and on the rim of the samples.

The summary of the results are as follows; owing to the difficulty of controlling the fire, the bonfire, and the bonfire in the pit, were proved not to be suitable for the production of the black-topped pottery. The updraught kiln was also unsuitable, because of the organic material for the carbon adsorption being entirely burnt out by the upward flames. On the other hand, we succeeded in reproducing the black-topped pottery by using the two-step production method. However, it is highly probable that this method can be applied to smaller pottery, but not to larger ones. The reason for this assumption is that it is thought to be difficult to remove the large pottery from the hearth. Of our experimental firings, the mud-covered bonfire was the most successful method. Its operation was so easy that once the fire was set, there was no need to do some treatment during the firing. Additionally, it needed less fuel than in the bonfires and the updraught kiln. Evidence of the mud-covered bonfire has not yet been found on predynasatic sites in Egypt, but it may be due to the property of the mud-cover being broken when opening. On the contrary, the absence of obvious kilns from this era might suggest the existence of the mud-covered bonfire. Moreover, from the negative result of the updraught kiln, it might be assumed that the primitive firing methods of the black-topped pottery were gradually vanished as the new technique of the updraught kiln was introduced into Egypt.

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