First step: Fight the thorns, slopes, bugs, heat, to pick the big blackberries that are so abundant and so seedy that most people reject them. I spent most of the morning picking berries along the edges of our property and ended up with about 2 gallons of berries.
Years ago, I found a really great device for removing the seeds - It's called a "Squeezo" - The berries go into the hopper, and then are squeezed by pushing them through an auger - where the juice comes out through the screen, and the seeds are pushed out the end.
It's messy - so I set up outside on the picnic table to do the squeezing.
I ended up with enough juice for two batches of jam. I use the same recipe for all my jams - I first of all ignore all the warnings on the pectin package that says "DO NOT ALTER THE RECIPE". I use eight cups of fruit,
which I pour into my biggest saucepan - which covers about the bottom two inches of the pan.
I add one package of pectin for low sugar jam, and mix it thoroughly into the fruit. Bring the mixture to a full boil on high heat. Then add 8 cups of sugar and stir in until it is all dissolved, returning it to a full boil. Boil for one minute.
This recipe makes approximately 4 quarts of jam - sometimes 3 or 3 1/2 - so I get an assortment of clean jars in various sizes and fill them with the hottest water I can get out of the tap and leave them in the sink while the jam cooks. I put the lids I think I'll need in a pan of water and let them boil while the jam cooks.
When the jam is cooked, I empty the water out of the jars and pour the jam into them. I carefully clean the top of each jar and put the lids on as tight as I can and turn the jar upside for a couple of minutes.
This makes all the jars seal for some reason. If I valued my time at anything, this would be some very valuable jam. But there is the entertainment factor to consider - I really enjoy making jam!