It's been a long time since I processed a lot of seeded grapes. But, if I remember correctly, I rinsed them, removed as many stems as possible, put the whole mess into a really big pot, added a small amount of water, brought it to a boil and let them sit til cool. Then, I ran the whole mess thru a ricer, which worked great cause it kept the seeds out, but allowed pulp and juice to go thru. Then, I put the juice in plastic bottles and froze them. Used them as needed. It was truly delicious juice. In those days I grew Concord and Niagara grapes. Niagara is my favorite grape; white and seeded. Enjoy!