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I understand (from experience) how to brew with extract and steeping specialty grains.

I understand (from reading numerous books, blogs, etc.) how to do an all-grain mash.

I see little on how to partial mash. Do I add the specialty grains to the partial-mash or after? Do I sparge the partial-mash? Do I wait the hour that an all-grain mash requires? Typically my beers take 6(or so) pounds of malt syrup, what percentage of malt should be partial-mashed and how much should I reduce the Malt Extract by to compensate (ie, 1 pound of mash = X pounds less syrup/powder)?

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Just wanted to say you've been asking some excellent questions! – hookedonwinter Apr 21 '10 at 19:02
Agreed w PJ. Keep it up. – brewchez Apr 21 '10 at 22:11
up vote 4 down vote accepted

When I do a partial mash, I heat about 3 gallons in my kettle to 155-160˚F. Then I'll put my grains in a grain bag, and leave them in the water for about an hour. Generally, most of your fermentables are coming from the extract. The grains in the partial mash lend mostly color and flavor, and not too much sugar, though they do give some.

After an hour, I'll pull the bag out and pour some sub-boiling water - around 180˚F - over the grains. This is sort of a sparge, but it's pretty weak in terms of sparging.

Since I have a wort chiller, I'll then raise the volume of wort the kettle to my desired amount (around 6 gallons), bring to boil, and go on my merry way.

As far as changing the recipe due to extra fermentables, I generally don't really worry about it. Maybe a little less sugar if you've got some really fermentable grains, but I also like big beers :)

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I like PJs answer, so I'll mention percentages. I think starting at twenty % of the total fermentable is a good place to start. Then you work up more and more by say 10% at a time as you are comfortable and you equipment allows. Eventually, you'll be doing 50-60% from the partial mash and you'll be just one step from going around the corner to all-grain brewing.

Partial mashing and the percentage of total grist is basically the gateway path to full all grain brewing.

In fact when I brew I still keep a little DME on hand just in case I miss my OG. In that case you could actually say I have a 90-95% partial mash with only 5-10% from extract! I guess you'd call that partial extract. :)

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I'd call it an "almost-all-grain." I did it for several batches before I finally scaled up to "normal" all grain :) – Graham Nov 22 '11 at 13:30

I wish I could up brewchez's answer but don't have enough "reputation"

Typically stating out on partial mash are just for flavor and color, loosely all your fermentables come from the extract (even brewing a big beer I use light liquid malt extract). I steep the specialty grains for 20 minutes not an hour just enough to get color and flavor, you could "sparge" but I just crank up the kettle after 20 minutes then take the grains out when it hits about 170F. On another note when stating recipe formulation compile the info from several like recipes to make one, each recipe you find should be formulated for the proper O.G and F.G or close so no need to calculate.

Good Luck

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