top weight

[xlogger]

Took my first load out of kiln yesterday after building some 4x4x10" concrete forms to put on top. I figure each one is about 13-1500 pounds. The load was 9/4 Ash and it came out nice and flat. I just have not in the past used enough weigh.
Now got a question. Where do you see most of your cupping in drying? My solar kiln is just not high enough to put much on it and my air drying I do try to set another rack of wood on top of them. I think I'll build about 4-6 more forms and this time maybe bring in a load of screening from rock quarry and fill them up. That should be good weigh and what left over is always a use for around the mill.

[GeneWengert-WoodDoc]

Cupping tendency is high at two times...above 30% average MC and below 30% average MC.   :D  From a practical point of view, we will see more cup 
when drying slowly (high RH) at higher MCs (above 40% MC roughly), 
when rewetting the lumber between 20% to 40% MC, and 
when over drying (under 7% MC).

When drying fast, we get a dry outside shell that is nearly twice as strong than the wet wood, so this helps keep the lumber flat.  If we rewet the shell, this eliminates the strength and so cupping results.  As we overdry the lumber, wood shrinks more and more.   Incidentally, flatsawn cups more, and closer to the pith cups more.  Finally, lumber cups toward the bark, as the bark face has more flatter grain than the other face.

[Nebraska]

I haven't drank enough coffee yet this morning but it occurred to me if one ran their cement weights through the kiln and they were dry and coated them with epoxy paint (don't know how much heat it will take) or maybe thinned gasket making silicone rtv high temp stuff it might slow down the moisture reabsorbung between trips through the kiln, old tractor front end weights come to mind as well.  Just a thought.