Even though you have carefully treated and dried your fresh cut wood cookie with Pentacryl or Wood Juice you are seeing some cracking on the inside. This is not due to a drying defect, since normal cracking during drying occurs from the outside rim in towards the pith (center of the wood cookie) to relieve the tension. See photo below.
Instead, the inside cracks are occurring from the environment the tree “grew up” in. Basically, “shake” or “ring shake” in fresh cut trees, is a separation or crack in the wood that runs parallel to the growth rings, rather than across the rings.
There are several different views on the causes for this. The most prominent is that the separation is caused by a weakening in the wood due to anaerobic bacteria that comes into the tree through the roots. Enzymes are created from the bacteria and cause the wood cells to become weaker, thus creating the cracks. This appears to be more common in warm and wet soil areas and occurs in both soft and hard woods.
When cracks or separations start at the pith (center of the cookie) and extend across the growth rings, it can been referred to as “star checks” or “wind shake”. These cracks are said to be caused by stress on the tree. For example if the tree grew in a high wind area or leaning on the side of a hill.
Using Pentacryl on the fresh cut green wood, or Wood Juice for the wood with a lower moisture content, will prevent the “normal” cracking and in these already challenging wood cookies. Although “shake”, “wind shake” and “star checks” are natural occurring and unavoidalbe in wood, the products will help to minimize the effects.