I take issue with the belief that "woodies" not need to be seen on both sides on the cent. While it could happen, the odds of a true "only one side woodie" have to be astronomical! An improper alloy mixture in metal is very similar actual wood, where the "grain" flows, usually in one direction. if a coin's "grain" can be seen on one side and you cut the coin in half, the improper alloy is mixed through the copper and would be seen running through metal and especially considering the thinness of a cent, it would only make sense the improper alloy "grain" would appear on the other side.
A drop of ink on water would float on the surface, and if then "stirred" the colour striations of ink would mix with the water and not simply remain of the surface. I think improper mixture of metals would act similarly with a cent. A "true" woodie would show the grain on both sides. If a similar effect is seen only on one side, I contest it is not a "true woodie" but rather feeder damage or a lamination defeat or some other event. The odds of taking a thin sheet of plywood and seeing wood grain only on one side while not impossible, the odds would be extremely high.
I am personally not a metallurgist, I barely made it through chemistry at University, but logic tells me that if you see wood grain flow through a piece of wood, a similar effect would/should flow through a very thin piece of improperly mixed alloy in metal. Plus, I personally have seen hundreds and hundreds of true woodies and have seen the improper alloy mixture noticeable on both sides of coins, US and Canadian cents. Am I 100% right on this? Probably not, but this is what I believe to be true.
