1. Insufficient yeast
2. Too much salt
3. Improper mixing
4. Extremely old dough
5. Dough too young
6. Dough chilled during fermentation period
7. Excessive punishment of dough in machines
8. Dough loaves too small for pans
9. Underproofed
10. Oven temperature too high
11. Mix water too hot—yeast killed
12. Very old flour (over a year)