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Hydrated lime, limestone differenceI summarized the information from various sources on hydrated lime and limestone. Let's begin with a quote from TMC, chapter 9: "Buffering agents are used to counter the acidic effects of peat and other casing materials. Calcium carbonate (CaCO3) is most commonly used and comes in different forms, some more desirable than others. 1. Chalk: Used extensively in Europe, chalk is soft in texture and holds water well. Chunks of chalk, ranging from one inch thick to dust, improve casing structure and continuously leach into the casing, giving long lasting buffering action. 2. Limestone Flour: Limestone flour is calcitic limestone mined from rock quarries and ground to a fine powder. It is the buffering agent most widely used by Agaricus growers in the United States. Limestone flour is 97% CaCO3 with less than 2% magnesium. 3. Limestone Grit: Produced in a fashion similar to limestone flour, limestone grit is rated according to particle size after being screened through varying meshes. Limestone grit is an excellent structural additive but has low buffering abilities. A number 9 grit is recommended. 4. Dolomitic Limestone: This limestone is rarely used by Agaricus growers due to its high magnesium content. Some researchers have reported depressed mycelial growth in casings high in magnesium. 5. Marl: Dredged from dry lake bottoms, marl is a soft lime similar to chalk but has the consistency of clay. It is a composite of clay and calcium carbonate with good water holding capacity. 6. Oyster Shell: Comprised of calcium carbonate, ground up oyster shell is similar to limestone grit in its buffering action and its structural contribution to the casing layer. But oyster shell should not be used as the sole buffering agent because of its low solubility in water." As you can see, Stamets relies on limestone flour = CaCO3 A few other quotes: from http://www.chemicallime.com
from http://www.chemicallime.com
From http://www.dragonchemical.com/SL2905.htm
OK, let's sum up:
It is stronger than calcium carbonate in raising the pH, according to the above source it has an Calcium Carbonate Equivalent of 126.94%. Then it also says 1,480 lbs. of this material equals one ton of standard liming material.
Now, the major problem I see is the pH of the hydrated lime. When you use limestone flour, you can add as much limestone flour to your casing mix as you want, but still the pH won't rise aboove 8-9. With hydrated limestone once you neutralized the pH by adding exactly the proper amount the hydrated lime, pH will rocket towards 12.4.
Now what can we do about it:
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