Air dry time of thicker stock hardwoods??

[kilnguy]

I dry for a company who's firm belief is to 'get it in a kiln as quick as you can'...with the underlying assumption that we remove all the variables (sun, rain, varying MC's, humidity, etc) and control the entire process from green to dry...the quality of the lumber outweighing the additional cost of the kilns.  At our facility I typically dry 4/4 stock of all your major hardwood species.  We have recently begun to dry some heavier stock, particularly 6/4 and 8/4.  My question is...are there some thicknesses that dry better with some proper air dry time (i.e. T-sheds, shade cloth, etc) on them rather than putting them in a kiln as soon as you stick them??? 

[Joe D]

Can you maybe give us a little more of hint of what species you are drying, etc? Thanks.

[kilnguy]

My specific thick stock is 6/4 and 8/4 ash...and 6/4 white oak.

[MichaelM]

My 2 cents worth -
Your company may well be right, especially if you already have the kiln capacity to handle all of your production.  But you are also right, especially as you go to thicker material and kiln capacity becomes limited.  If there was one correct way to approach this then everyone would do it that way.  It also depends on your yard space, airflow and local weather, inventory cost for the material, and probably factors that other people can point out.  Mike M. 

[Joe D]

Ash I would probably opt to kiln dry direct from the saw to protect the color. Time wise it would not be unbearable.

White oak, 6/4, if you are going to kiln dry it from the green, be gentle. You need to insure that you really have a kiln you can precisely control and hold the desired dry bulb and wet bulb. Starting temperature should be much lower than suggested by the book. Dry off the daily moisture loss off of your samples. Expect a 70 to 80 drying time.

So in most cases you come to the conclusion you need to shed dry the material prior to kiln drying. For this you need a shed that you can keep the lumber in a high relative humidity from the start. So don't use something like a T shed. You need to have enough lumber in one area to raise the humidity. Or in other words block of low humidity airflow to the lumber.