O.K. Here's my first year experience trying to get black walnuts...
After extensive research on the internet (the best source of true information out there) I have come up with this and it has worked O.K. so far...
People said that if you pick the nuts up when the husks are brown, the husk juice will have penetrated the nut and altered the taste of the nut meat, so you should pick them up when the nuts are green.
People said that you should run them over with tires, build a de-husker with an old knife, etc... I was looking for a lazy, ah, errr, time efficient method so I opted for the cement mixer method. Here's how that went...
First batch: slightly brown, slightly soft husks.
3 parts walnuts.
1 part water.
1 part gravel.
Turned it on. 20 minutes later I had a brown gooey mess that stuck the nuts to the sides of the mixer and they were not tumbling or cleaning themselves at all. So, I had to add more water... lots of water, to get them tumbling. That makes splashing, which causes a mess. Quickly rolled the mixer out into the yard over a spot where I would not care if the grass died. After about an hour, I had a very messed up mixer, but the walnuts were actually de-husked. I had to use long rubber gloves and old clothes, made a mess, etc... but I turned a 20 gallon container of nuts into three 3/4 full 5 pound mesh orange sacks of husked nuts with only about 10 minutes of actual labor. Not bad. I hosed them off a few times, let them dry for a while and bagged them up. Everyone says to hang them where they will not freeze for about 5-6 weeks before cracking them so that the meat shrinks from the nut, so now I wait.
Second batch: green husks.
Tossed in the nuts, tossed in the gravel, turned it on and started adding water until it tumbled well. 3 hours later 1/4 of the nuts were still in their husks. I may need bigger rocks. Anyhow, the results were still clean nuts ready to wash and bag.
I noticed the green husks nuts came out light gold while the brown husk nuts came out very dark, so the walnut stain may have an affect on the flavor. I will let everyone know how the taste is on both batches when I start cracking them. I will do test cracks each week to check. The cement mixer is a mess.
