For grapes, the only instructions are for jelly, and it would take some dedication to follow those. We have three different types of grapes in abundance right now. Concord on the left - sweet unmistakable taste, but with tough skins and seeds - mostly we let the birds, bears, and raccoons have them. In the middle, Interloken, a variety of sweet, seedless, eating grape that does well in the Pacific Northwest where we live. On the right a much smaller blue grape that is tart but seedless. This is the variety I decided to experiment with.
A crucial tool for my jam making efforts is a really good blender (This one is a Blendtec, but a Vitamix also works well). It can take the big wild blackberries and crush the seeds to make a smooth paste. For the grapes, I separated all the branches and ends, leaving only small ripe grapes in the blender.
I have a standard recipe that I use for ALL jams that I make - 6-10 cups of fruit puree (more for blackberry, less for raspberry - after years of experimentation I have a pretty good idea of how much pectin it takes to set up different types of fruit. I went on the low side for the grapes, so I used 6 cups)
I use exactly the same amount of sugar as fruit and one package of NO SUGAR pectin (it sets up much better than the type that calls out sugar).
Wash jars and leave them full of hot water until you are ready to use them. Put jar lids into a pan of boiling water and simmer while you make the jam.
Stir pectin into fruit puree while it is cold, then bring to a full rolling boil that you can't stir down.
Add sugar all at once to boiling fruit and stir constantly until it comes back to a full rolling boil. Boil for one full minute, and then pour into jars after you empty the hot water from them.
Put hot lids onto thoroughly cleaned rim of each jar and tightly screw the lid down with the ring.
Turn jars upside down for a few seconds after the lids are on tight. This helps them to seal.
There are studies that say red wine is good for you and that red grapes have the same effect on your body - so while I have never heard of grape jam, logic says it should be good for you also. It has the texture of a thicker apple butter and a slightly tart taste. It may become my favorite jam!