Weight versus Volume...I've got some weird thoughts about this.

I suspect that the humidity doesn't really affect the weight of the flour all that much. This is not to say that you might not still be adjusting how much flour you'll be using. If you think about it, we run into exactly the same difficulty with just how much flour and water to add when the humidity is high when using volume measures. In the end, it comes down to feel. If the dough feels too wet, we add a bit of flour....

I think the reason so many people prefer to measure by weight rather than volume is that the amount of flour going into a volume measure can vary drastically, depending on how heavily packed the flour bag is, if the flour is fluffed and scooped, if the flour is spooned in and levelled with a knife. There can be quite large variations with volume measuring.

-Elizabeth, casual measuring school (sometimes measurer by weight on an inferior spring loaded scale, sometimes measurer by volume using the fluff and scoop method)

Lots of good questions from squatteam.

Let's start with the consistency of the moisture level of flour.  In the USA, millers adjust the grain before it is milled to 14% water by weight.  Doing this helps them mill a consistent product, helps the life expecancy of the equipment and so on.  So, they water dry grain and let the water get absorbed and dry out wet grain.  In France the magic number is 12%.

Interestingly enough the multi-layer paper sacks used by most millers are very effective at maintaining the moisture levels in the flour.  Having lived in very wet and very dry areas, I can tell you the flour is quite consistent.  As a consumer to keep the flour moisture level close to right is to fold the bag.  Tape it if you want.

The curve ball in this is if you grind your own flour.  You have little to no control over the moisture level of the grain you purchase, probably have no way to measure it and no effective way to adjust the moisture levels.  So you just have to work with what you have.

However, in another forum someone asked about extreme variations in flour moisture and how much difference it would make in the dough.  I played with a spreadsheet and found if the moisture leve of the water dropped or raised as much as 8% (which is not at all liely) it would only change the dough moisture levels by about 2%.  Not a big deal for most of us.  So the variation between store ground whole wheat and different batches of home ground aren't going to be that significant with regards to moisture levels.

Now then... why weigh or measure by volume?   In a usenet baking group a number of people who had scales weighed a cup of flour.  And they ranged from less than 100 to more than 200 grams.  The range was from people who sifted their flour twice and took care not to compact the flour in their cups to people who aggressively scooped flour from the bag and didn't level the cup.  Worse yet, the scoopers reported as much as a 25% cup to cup variation.  This variation leads toissues where someone reduces teh amount of flour and the dough is drier than last time.  Or increases the flour and the dough is wetter than last time.  Leading to comments about the water being wetter, or dryer, than usual.

Most flour companies and  most cookbooks tell you a cup of flour should weigh about 120 grams, and this is true for white, whole wheat and most rye flours.  It is not true for bran or germ, however.

Still, when someone tells you to use 4 cups of flour, what do they mean?  400 grams, 480 grams or more than 800 grams?  Flour, like salt and sugar, is a granulated solid and it can settle out.  Similarly, table salt and Kosher (or Koshering) salt weigh different amounts per tablespoon because with the smaller crystals of table salt, you can get more salt into the tablespoon.  Kosher salt has less sodium per tablespoon because there is less salt in a tablespoon when you use Kosher salt than table salt.

Emily Beuhler in "Bread Science" suggests that weight is a more accurate way to predict how many molecules of flour or salt you are putting in your mixing bowl than measuring by volume.

So, how should you measure a cup of flour to get the more or less standard 120 grams?  Sift the flour once.  Use a scoop or spoon to drop the sifted flour into a measuring cup.  When the cup is over-filled, use a straight edge to scrape off the excess flour.  You should be within 5 grams of the correct weight almost every time. Many people think this is more trouble than it's worth.  Which  is why the scoop and wonder why their bread doesn't come out the way the idiots in the cookbook said it would, and why it never comes out the same way twice.

All that said, I think that there are three tools that will hel[p any learning baker learn faster and develop their skill more quickly.  A set of scales, an oven thermometer (many oven thermostats are woefully inaccurate), and a chef's thermometer to help control dough temperature and check when baked goods are really done.  BUT in the end, it is important that the baker be in control.  Just because the cookbook said to bake the bread for 40 minutes at 450F, or until the  crust looks like this, or until the crumb has a temperature of 205F doesn't mean that is gospel.  You have to use the tools to buil your skills to make the bread you want to make. 

All the professional bakers and good home bakers I know carefully measure.  And then they feel the dough and adjust if needed.  They taste the dough to make sure it tastes the way it should.  Did we forget the salt this time?

The tools should help you get close  to where you need to be, your skills take you to the next level from good to great.  You need to learn how to tell by touch and smell when bread is done.  You have to be able to tell what dough should feel like.  Some day your scales won't work correctly and your dough will feel wrong.  You can pitch the dough and start over, or you can know from your experience that it needs another handful of flour.  One time one of our thermometers got out of adjustment and my night baker used the thermometer to check the bread.  It was actually about 165F inside, not 195.  It was like pudding inside.  We lost an account over the matter.  If she had been far enough along in training, she could have felt the bread and realized it felt wrong and corrected the matter.

So.... remember, YOU are the final judge, not the tools.  YOU are the master, not the tools.  YOU are the artisan, not the tools.  The tools are just there to help you be better, and to be better more quickly.

Hope my musings help,

Mike

Mike above hit on the major issue: how well packed is the flour and what a difference that makes.Here's an experiment you and your 8yo can do next time you bake to get a real feel for it.  You'll need 2 large used clean cans in addition to what you normally bake with (I run my cans for crushed tomatoes and such through the dishwasher before recycling them; they would be perfect).

 Take half of the flour (by weight) you are planning on using and sift it into one of the cans.   with a spoon, carefully level it out.  Take the other halfof the flour and dump it into the other can.  Tamp the flour in this second can thoroughly.  When it's well tamped, look at the the difference in volume of the flours in the two cans.

most effectively: 

So.... remember, YOU are the final judge, not the tools.  YOU are the master, not the tools.  YOU are the artisan, not the tools.  The tools are just there to help you be better, and to be better more quickly.

I purchased a scale, used it for a week or two, and then set it aside.  I'm sure that I will use it again, but since I am basically making the same bread a couple times a week, I am able to just "wing it" now by the very feel/nature of the dough.  Sincerely, though, I could NOT have become as adept at it without that scale.  It proved worth it's price (around the mid-twenty bucks, range), and I'd buy it all over again.  My bread making skills improved ten-fold immediately.