Canning jars are excellent, as are empty pickle or jam jars. Be sure the jar is clean, so the started doesn’t get contaminated.
Any type of flour will do, but remember that you need a good amount of gluten for your bread to rise properly (wheat, barley, and rye contain gluten).
Room temperature is usually warm enough to provide the right conditions for yeast to grow. If your house is on the colder side, place the jar in a warm part of the kitchen. Cover the yeast jar with a heavy cloth to keep it dark.
Flour varies in absorbency, so using exact measurements isn’t nearly as useful as relying on your judgment. You can mix the dough together easily using nothing but your hands and the mixing bowl.
Dough rises faster when it’s in a warm, dry place. If your kitchen is cool, turn on the oven to 200 degrees Fahrenheit, tilt the door open a few inches, and place the bowl inside while the dough rises. You can let the dough rise in the refrigerator overnight.
The dough should begin to look glossy and smooth. Keep punching the dough until the consistency looks right. You can use a stand mixer with a dough hook attachment instead of your hands.
