I'm with DSD on it's wetness negating the dessicated properties.
I have pictures of earthworms in my 90%DE soil.
Lol....in researching how long we've mined DE...
"In 1836 or 1837, German peasant Peter Kasten discovered diatomaceous earth (German: Kieselgur) when sinking a well on the northern slopes of the Haußelberg hill, in the Lüneburg Heath in North Germany. The deposits are up to 28 meters (92 ft) thick and are all of freshwater diatomaceous earth."
I learned August 31st is "National DE Day".
You know what that means!
Marketing!
Everytime they are trying sell you BS, it becomes a "day".
We can't think it took 200 years to notice something kills bugs or fungus, how did we just find this stuff out a few years ago?
Anyway that first article sounds suspect....
"Conclusion
Does diatomaceous earth kill fungus? Yes. This article has revealed that it not only kills fungus, it also kills other external parasites."
Lol, no worries it was fact checked! Lol!
Proper informational writings would conclude, "our cited sources and investigative observations have revealed".
No, they just say it's so cuz they say it! BS!
.
Of firing temp.....
I reckon since DE is fired in a Rotary Kiln to rather loose tolerances the large DE, wether sifted prefire or after, would tend to gather more heat as it would air in a mix.
The temps are likely set the same.
Point being we will always see variation in quality from time to time, since this product is made to throw on the floor.
Sorce