Baked beans still firm after soaking and hours of cooking
Since it's hard to know the age of your beans, it's best to cook them before you start adding sauce ingredients. My approach is:


soak them about 20 hours. Depending on how much water they soak up you may add more halfway through - if you set them soaking in the early evening, check them in the morning
drain, rinse, and then boil for about two hours, checking to see if they are soft. If they're not soft, don't move on, keep them boiling (a low boil, but more than a simmer)
once they're soft, drain them, add the sauce and whatever else (onions, bits of ham) and put them in the oven. I typically give them an hour in there but at this point it's about reducing the sauce, getting the flavours to mingle and soak in, that sort of thing.


My beans come from the local farmer who supplies all my fresh vegetables, but I don't always use them all right away. This week I cooked some cranberry beans from the late summer of 2013. They were creamy and soft using this technique.