Salting meat was a method of preservation used in the days before refrigeration. My Memere would salt all meaty chunks of fat and store it in a crock in the cool cellar where it would be available year round. We do the same, except we have a "fermenting fridge" in our basement. With modern mechanicals in many cellars nowadays, such as the furnace, hot water heater, and the washer and dryer, it is a rare cellar that maintains a constant cool temperature suitable for safe food storage. This is where the second fridge comes in handy.
What you use to make salt pork is a matter of preference. I like the forward end of the bacon, the part that is on the shoulder quarter that gets doesn't end up with the bacon. This will make sense to you if you cut up a side of hog on your own. Otherwise, just trust me on this one.
That little bit of lost bacon won't be enough to prepare a year of meals requiring salt pork, however, so I tossed any nicely marbled piece of fat into the bucket destined for making salt pork as we did the butchering. Some were just fat with no meat....I chose pieces that seemed firmer to the touch, that would dice well, putting softer pieces into the grinder for lard. Chunks of fat that looked suitable were added to the pail, no matter where on the pig they came from.
Dad likes to use meatier salt pork, so he chose fatty meat....I chose meaty fat. Jack Spratt, and all that!
If you don't happen to be butchering a pig yourself, you can use any fatty cut you can purchase. Boneless country style ribs make great salt pork. The fat trimmed from very fatty chops can be used....Hey, salt down a few chops while you're at it, especially if you like meaty salt pork. Just be sure there is plenty of fat, so trimmed bits work great. You can salt them in a small jar or bowl in your fridge. No need to make 4-5 gallons like I did. I do tend to lose control when it comes to anything even remotely resembling bacon!
These pictures were taken a few days later, when I brought the jars up from the cellar to add some brine and weight down the pork. You can actually do this all on the first day you make it. I didn't, because the big jars I wanted to use were occupied and needed cleaning, so I started my salt pork in several gallon jars and then re-packed it into these two 2.5 gallon jars for longer storage.
If you don't have a crock with a weight made for the crock, you can use the handy-dandy Ziploc freezer bag. Or a large scrubbed and boiled brick or rock. Or a rock and a plate if you have one that fits in your container. Or a canning jar filled with water instead of the rock. The possibilities are endless.....your goal is simply to keep that floating fat immersed completely underneath the brine at all times. Air = decay. We don't want that.
Wait about 10-14 days before using any of the pork, giving the salt time to draw much of the water out and for some of the salt to penetrate and flavor the pork.
The type of salt you use is also a consideration. Ideally, a good sea salt is used such as Celtic brand, any of the pink Himalayan salts, Redmond Real Salt, or as we did, home made sea salt (that is another story altogether!) Quality salt is an important nutrient and it is worth the extra expense for this purpose. Fat from pasture pigs, coupled with high quality salt, will yield superior health benefits. Save money elsewhere (buy cheap toilet paper, I always say!) and splurge here. You are worth it.