Dry Brining is about salting for flavor and moisture retention ahead of cooking instead of wet brining and the sort of diluted flavor some perceive from that technique.

This technique is best used on cuts of meat that have not been presalted, either with a salt solution, or koshering. You need to be in complete control of the amount of salt. You'll need to seek out minimally processed meat, poultry especially, for this technique. Generally speaking, poultry and lamb work best with this technique.

First, some definitions of terms, paraphrased or copied from Wikipedia and other sources.

Solvent: the liquid the solute is dissolved in. Water for the most part in brining. 
Solute: The dissolved substance in the solution. For the most part, salt in the brining process.
Semipermeable membrane:  biological membranes (cell walls of meat tissue) are semipermeable. In general, these membranes are impermeable to large and polar molecules, such as ions (SALT!), proteins, and polysaccharides, while being permeable to non-polar and/or hydrophobic molecules like lipids
Osmosis: Osmosis is the spontaneous net movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.

Let me summarize then. In a brine or dry brine, salt draws water out of the cells which increases the concentration of salt inside the cell. Simultaneously, the added water to the solution dilutes its strength pushing both the solution and the cell towards equilibrium. 

So when Rick Rogers blogging at epicurious says,
How does this dry salt rub work?  The salt draws a tiny bit of moisture from the bird and opens the skin pores.  This moisture mingles with the salt and works its way into the turkey muscles, seasoning the bird throughout through osmosis.
He got it wrong.

When bbq.about.com says,
To dry brine a turkey you apply salt directly to the meat, like using a rub. The salt draws out some of the moisture in the meat, mixes to form a salty liquid that is absorbed back into the meat with a higher salt concentration.
He got it wrong.

When Fine Cooking says the same thing, they got it wrong. 

The recipes work, yes, but their explanation doesn't.

Yes even, Wikipedia sources McGee's On Food and Cooking and offers this explanation: 
Brining makes cooked meat moister by hydrating the cells of its muscle tissue before cooking, via the process of osmosis, and by allowing the cells to hold on to the water while they are cooked, via the process of denaturation.[2] The brine surrounding the cells has a higher concentration of salt than the fluid within the cells, but the cell fluid has a higher concentration of other solutes.[2] This leads salt ions to diffuse into the cell, whilst the solutes in the cells cannot diffuse through the cell membranes into the brine. The increased salinity of the cell fluid causes the cell to absorb water from the brine via osmosis.[2] The salt introduced into the cell also denatures its proteins.[2] The proteins coagulate, forming a matrix that traps water molecules and holds them during cooking. This prevents the meat from dehydrating.
Rather, we know osmosis dehydrates cells, (see) secondly, cell membranes reject salt ions in osmosis. If osmosis worked as described, our uptake of water in the ocean or the bath would make us all sick and kill many of us.  Of couse, the cell needs some salt to work. How does it transport salt ions? Transmembrane protiens, and that link also disccusses the rejection of salt in osmosis in the first answer.

I respect McGee and really find his book useful. But on this topic, his explanation is incorrect. I hope he corrects it in the next edition. 

The last part of the wikipedia explanation is correct. The increased salt concentration in the cell (because of the lost water) partially denatures the protein of the meat. The denatured protien forms a web that helps retain the moisture during cooking that is already present in the flesh. You lose less moisture during cooking, though you lost some in the brining or curing. 

So, on to dry brining, which is most often seen as a treatment for poultry. There are a couple of routes used in dry brining, but it largely forms two categories: koshering and pre salting. 


Koshering poultry is a ritual process that involves a salting step to draw out any remaining blood. For the purposes of this discussion the rabbinic oversight and other steps are not pertinent and when I say koshering, I am referring to just the salting process. Chabad.org has a good article on koshering meat if you want alll of the details. 

When Cook's Illustrated was doing their brining research, they observed that a koshered chicken was quite close in flavor and juiciness to a brined bird and often recommended using kosher poultry if you didn't want to brine the bird yourself. This led me to look in to the koshering process myself because kosher poultry is not easy to find my area. 

The bird is rinsed, then thoroughly salted. It stands salted for 1 hour, then is rinsed three times. For just flavor purposes, the important things are this. The bird should be damp so that the kosher salt will adhere to the bird. Salt the bird inside and out, taking care to salt all folds and crevices. Let it stand for an hour on a rack or board so it can drain any liquid. When the hour is up, rinse it thoroughly inside and out. 

The hour of salting time is convenient as a home cook. I can use that time as the time for the meat to come up to room temperature before cooking it. On the down side, you've rinsed the bird so the skin will be a little damp for getting that optimal crackly texture. You could dry it in the fridge for another day if that is your preference. 

I often include herbs and spices with the kosher salt to help preflavor the bird. After rinsing, I'll usually reseason with more herbs and spices, but no salt. It's salty enough at this point. 

Koshering is a very high salt process, a tablespoon or more a pound of meat.  In the more common applications of dry brining linked above for overnight, you'll use less salt, more on the order of a teaspoon per pound. And you'll still rinse away excess salt. It's similar to brining in that strong brines are used for a short period of time, where weaker brines are used for longer periods. 


In pre-salting, the amount of salt used is much less, and the time is much longer. more on the order of 1/2 teaspoon per pound and there is no rinsing. 

Molly Stevens gives some good basics on pre-salting a turkey:  
Presalting is the key to a juicy bird. One to two days before Thanksgiving, remove the giblets from the turkey (saving them for later if you like). Then pat the turkey dry with paper towels. Measure out about 1/2 teaspoon kosher salt per pound of turkey (if you have a 10 pound turkey, you’ll want 5 teaspoons kosher salt, for a 15 pound bird, it’s 7 1/2 teaspoons, and so forth; then simplify your life by converting teaspoons to tablespoons. Hint: There are 3 teaspoons to every tablespoon). The best brand of kosher to use is Diamond Crystal, because it has no additives, and the large, flakey crystals dissolve readily. If you use another brand, such as Morton, cut back the amount of salt by a smidge.

Sprinkle the measured amount of kosher salt and plenty of freshly ground black pepper (and any other seasonings you’re partial to) liberally all over the turkey, spreading a little in the cavity and being sure to season the back, the breasts, and the meaty thighs. If you’ve never pre-salted before, this may look like too much salt, but it’s not. As the turkey sits in the refrigerator, the salt will gently permeate the meat, improving the water-holding ability of the muscle cells so that, when cooked, the meat stays juicy yet does not become overly salty. Arrange the salted turkey on a wire rack over a rimmed baking sheet, and refrigerate uncovered (this dries the skin, which helps it turn crisp during roasting) for one to two days. When you pull the turkey from the fridge after its salt treatment, the skin will be taut and dry with no trace of salt–and ready to crisp up nicely in the oven. (There is no need to rinse or wipe off the turkey.)
I've not developed nor have I seen rules for amounts or timing in this technique. Personally, I use it mostly on whole birds where the risk of overcooking the breast is high while getting the dark meat to cook to completion. The extra moisture held in the meat supplies a buffer to avoid dry breast meat. When cooking a pork or beef roast, or even cutlets and chops from pork or chicken, I can control their doneness individually as needed and so this technique offers less appeal to me in those situations.

There are those who advocate pre-salting just about every cut of meat. Food and Wine has an article that compares pre-salting on a variety of meat and found the best results in poultry and lamb. And that it was not well suited to tender pork.

Dry brining is a simple method to achieve much of the results of brining, but with less mess and hassle.