Originally Posted by hector
Just as Info :
I mashed 0.5 lbs of my home-roasted malt and after sparging it gave me 950 mL with the gravity 1.010 .
Water/Grain ratio : 2 qts/lb
If dark malts have no diastatic power , then what do those numbers in table 9 in the section 12.4.1 of John Palmer's "How To Brew" mean ?!
Crystal malts and chocolate malt do not have diastatic power, that is, they cannot convert any starches they may have to sugar. However, the grain is made so that any sugars there are crystalized. So you can steep it and get a few gravity points.
Say you make some tea with black tea. You get some water, and steep the tea in the water. You get some tea out of it. The same is true with chocolate malt, roasted barley, crystal malt, etc. You do get color and flavor, and a few gravity points from the malt. That is why you use it. That doesn't mean it was "mashed", as it has no power to convert. It was steeped.
In order to "mash" the grain, you must use a base malt that DOES have diastatic power. There is no other way. You can soak crystal malt all day long, and won't get more out of it than if you soaked it for 20 minutes. Same with chocolate malt, roasted barley, etc.
From the bottom under the chart that you quoted, Palmer says this:
"Steeping data is experimental and was obtained by steeping 1 lb. in 1 gal at 160°F for 30 minutes. All malts were crushed in a 2 roller mill at the same setting."
If you would have steeped your chocolate malt (which you did), you would get the same PPG. There is no advantage to separating your grains, as you got exactly the same gravity points as if you would have steeped them together.