<HTML>I don't think that Sandy has read or even heared of Lucas/harris, and I have doubts that Morris or Davidovits know it, either. Or if they know they ignore the basic informations in it.
Lucas/Harris "Ancient Egyptian Materials and Inustries" is still THE fundamental book about Egyptian production technique. From p. 74 on they write about plaster and mortar used in Egypt and have some interesting information.
"The mortar used in ancient Egypt before Graeco-Roman times was of two kinds ... namely, clay for use with sun-dried brick and gypsum for use with stone. ...
<b>No instance of the use of lime mortar in Egypt, or of lime in any form, is known to the author as occuring before the time of Ptolemy I (323 to 285 B.C.). </b>From this period and from later periods it has, however, been found and, from the few specimens analysed, it appears to have been, as is inly to be expected, of much the same composition as the lime mortar today."
Lucas/Harris p. 74
And now another explanation possibly of the trap Davidovits fell into...
"Gypsum occurs plentifull in Egypt in two conditions ... As found thus, gypsum is never pure, but contains varying proportions of calcium carbonate and sand, together with small amounts of other ingredients. <b>The presence of calcium carbonate ... has let those who are not familiar with Egyptian gypsum and who know only the purer European article, to imagine that it is due to an intentional admixture with lime, which in course of time has become converted tinto carbonate by natural processes, as happens in case of lime mortar.</b> ... Ancient Egyptian plaster of the kind under consideration is crude gypsum that has been burnt, powdered and slaked, and <b>any calcium carbonate and sand it contains are not artificial additions, but impurities derived from the raw material in which they occur naturally.</b>"
Lucas/Harris p. 78
And some closing words why Egyptians didn't use lime even for plaster:
"The reason for preferring gypsum to lime, although limestone is very plentiful in the country, even more plentiful than gypsum and also more accessible, was doubtless owing to the scarcity of fuel, lime, as will be shown later when dealing with plaster, requiring a very much higher temperature for burning, and hence more fuel than gypsum, and it was not until the advent of the Greeks and Romans, both of whom knew lime in Europe, where gypsum is useless for outdoor work on account of the wet climate, that lime-burning was practised in Egypt."
Lucas/Harris p. 75
And about the temperatures:
"Chemically, Gypsum is calcium sulphate containing water in intimate combination. On being heated to a temperature of about 100°C (212°F) gypsum loses about three-fourths of its water and has the property of recombination with water and forms a substance that sets and finally becomes very hard. The temperature usually employed for burning gypsum varies from about 100°C to about 200°C, but is generally kept about 130°C, which is a heat readily obtained. ... In order thatthe difference of temperature required to produce lime by burning limestone as compared with that needed to calcine gypsum may be appreciated, it may be mentioned that to convert calcium carbonate into quicklime a temperature of about 900°C (1652°F) is required."
Lucas/Harris p. 79
And about the often greyish colour of plaster/mortar:
"When the colour is grey, this generally is owing to the presence of small particles of unburnt fuel".
Well, let's summarize:
- Lime was never known nor used in Egypt before around 300 BCE
- for all mortars and plasters used during 4000 years of Egypt (mortar & plaster are known even from predynastic times) only gypsum is used
- gypsum as part of the pyramid blocks would easily detecteable and is out of discussion
If lime is a key point to Davidovits/Morris hypothesis, now the point is reached to push is overboard. If the Egyptians has KNOWN lime they would have used lime plaster, too. Somewhere. Funny thing: Gypsum Mortar was even used at the pyramids themselves. See Lucas/Harris p. 470, where several mortar samples are chemically analyzed:
1 from Hethepheres
3 from Khufu's pyramid
2 from Kaphere's pyramid
3 from Kaphere's valley temple
6 from the Sphinx
7 from the Mastaba of Shepseskaf
Funny. Using lime by the mega ton, but using gypsum plaster between the blocks...
The Egyptians truly must have been crazy.
FD :-)
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