ah! Thanks ChshreCat. I bought some ingredients to do an extract version of Edwort's Haus Ale recently. The fermentables called for crystal malt...only now (from reading Papazian's book) do I realize that that's STEEPING not MASHING (am I right?).
There's a guy on craigslist in my area selling a mashing cooler. What is that "manifold" dealy for?
Steeping is not the same as mashing.
However, they are very similar. You can mash on the stove in a grain bag just by letting the bag sit in warm water, just like in "steeping." In practice, here are the differences you need to know when mashing on the stove.
1) Temperature is more critical.
2) It takes longer. (about an hour for a mash vs 20 min for steeping grains.)
Simply put to mash you need to soak the grains in 153F water for 60 min, then rinse with 170F water.
Why?
With a mash you are converting starches to sugars, whereas with steeping your just extracting some of the flavors and sugars that are already there.
The reason the temperature is so critical is that the enzymes in the grains have an optimum working temperature. If it's too cold, the enzymes wont be activated, if it gets to hot the enzymes will be destroyed. There are two enzymes that are needed to do the job-- beta amylase and alpha amylase. Beta amylase works best at 131-150°F. Alpha amylase works best at 154-162°F. No problem right, we just do the enzymes one at a time. But this wont work. Beta needs the sugars broken down by the alpha amylase. However, if you mash at alpha's ideal range, you'll start to break down the beta amylase. If you mash at beta's ideal range you'll wont get enough alpha working. So what do we do? We split the difference and mash at 153F. It's a compromise. Neither enzyme is perfectly happy. But they'll both be able to do their job.