Joe, it's not that kiln drying is "bad"; usually it's a very good idea. With black walnut however, there are a few tricks to use in order to maximize the color.
First off, the drying rate is based upon the thickness and initial moisture content, with thicker and wetter wood requiring a slower rate. 4" thick slabs require an extremely slow drying rate or you will damage the slab.
Wood dries very poorly in log form, and it is customary for certain species (such as walnut) to retain their full moisture content in the heartwood for years.
Typical targeted moisture content for furniture is below 10% and above 6%.
Stickering is the process of placing 3/4" or 1" thick small sticks of dry wood in-between layers of your fresh cut lumber, in order to allow airflow around the sides of the boards/planks.
Scott
I agree 100%. When Joe said they felt "wet" after surfacing my first thought was.."don't even think about putting them in a kiln right now"
I believe those big 8/4" walnut natural edge planks you sold me last year were several years drying both outside and inside. I wasn't sure if they had ever been in a kiln, but after a year in my shop they're right down to 8-9 %.
In fact I just used them to make some more natural edge benches
Joe, I don't mean to criticize, but I have two different kinds of HF moisture meters and they are not even close to being accurate..might work on wet 2X4s, but not even sure of that.
IMHO it's pretty hard to find a usable meter for under $100. I now have a Merlin RF unit and it compares pretty well with Scott's "gold standard", a 4 point probe meter by Delmhorst, depending on the thickness of the wood.
I think Scott's goes for about $500 and mine was half of that. If you're not going to be buying a lot of wood with "unknown drying history" you probably don't need to go this kind of expense. ...but I would not rely on the HF meter readings.
If you're buying kiln dried wood from folks like Scott, or Anchor Hardwoods, or the Hardwood Store you don't need a meter. If you're going to use wood like the walnut pieces you just got, you probably do.
I would be glad to measure some for you if the occasion occurs, and I'm sure Scott would too.
Don