Theories And Questions On Woodie Cents.

Mike, in an attempt to be constructive, my opinion has evolved as follows: I think both the narrow and wide stripes are caused by insufficiently and/or improportionately mixed alloys. I believe the wider stripes are more insufficiently mixed than the narrow ones, and are thicker in volume as well. I believe this for a couple of reasons.
First, I believe one sees the narrow stripes in clad coins because the clad layers are less prone to this error (enough that the stripes are not wide). Second, I believe the narrow stripes appear as "superficial" when the coin is worn, because they are thinner by volume than the more poorly mixed wide stripes.
When it comes to nickels and clad coins with stripes, I think their frequent association with a gray or brown color is a direct result of an improperly mixed alloy of a different combination of metals than that of cents.
Mike, you are certainly at the top of your profession, so I just thought I'd offer an "other side of the coin" from a relative layman's perspective. JMO

As for clad coins, the stripes may come from the rolling process wherein the 3 layers are pressure joined. They are literally fused. The Cu layer is in the center with the two outer layers being the CuNi. I agree that the lines probably come from this rolling, process, in which great pressure is exerted. The direction of the lines may follow the direction of the sheets (film) as they move along the pressure rollers. Are they then annealed before striking? I know that the pressure bonds are enhanced by first roughing the surfaces of each metal coil/roll. Anyways, if they are annealed after the cladding step, then this may help explain. Too, it is possible that when rolled, the copper cores (coil) may "swell" up into the outer layers, enough to color it, especially if the roller is not 1000% smooth?

I now suspect that brown and gray-colored stripies found in nickels and clad coins are the result of both rolling and improper annealing. I suspect that the elevated temperatures of the annealing oven somehow bring out the striped pattern that is already latent in the surface metal. This conjecture would explain the greater-than-random association of stripes with discoloration and the uniform discoloration of the coins' edges.

This post is from Sept 2015.

Just my opinion Coop, they may be straight, but not necessarily. The cent only represents small portions of the lines. Long curved lines appear straight when viewed in small portions like a Lincoln Cent. Come to think of it, they appear straight on almost all Woodys, sometimes not continuous, sometimes wider or narrowly spaced. It all depends on the portion of the mix a particular planchet is made from. The widths vary on the OP's coin.
The insufficiently mixed portion goes all the way through on a two sided Woody, but part of the mixture is mixed better on the one sided Woody. The batches are unevenly mixed, some sufficiently and some not. Otherwise there would be all Woodys or no Woodys. If you cut through a coin to see the lines, the cut hides them. I guess I'm just a Traditionalist when it comes to Woodies. lol I do believe with the modern clad Woodies some could be roller lines, the discoloration seems to support that. When sanded or worn and the lines disappear supports it too, as well as the traditional Woody that doesn't go all the way through. One thing's for sure though, whether one believes Woody's are caused by an improper mix or roller marks, it's all theoretical.

I think asking something to stay perfectly parallel after being struck with 50+ tons of pressure would be asking a bit much. Thanks, Doug.

Probably when someone tries to sand the surface of one of these examples. If it is a bad mix, then it should show all through the cent. But if it is just a surface issue, then it would sand off. Then we will know for sure. I feel it will sand off the coin as it is just surface. On a woody, sanding the surface will not make this go away as it is deep into the planchet, not in the surface. I wish I had time. So maybe someday I will get a chance. Just too busy now to try this.