Wrinkling or stretch marks on a coin

Hard to say exactly what you mean without a picture, but for what I THINK you mean: A worn die is usually the explanation. Over time, the movement of metal-against-metal causes creases in the die that are transferred onto subsequent coins struck.

Often, particularly with large cents, you might hear this called the "Orange Peal" affect.

@BuffaloIronTail said:
When a die ages, "flow lines" start to appear. The devices start to gravitate towards the rim. Those "flow lines" are what I assume you mean by "wrinkling".

Pete

LOL....I knew there was a better word than the "wrinking" I used. Flow Lines is the right way to describe it.

It can be quite dramatic sometimes on Bust Halves, Large Cents, and the like

I've seen it on BH, specially on the stars. Fatigued die?

@Gunnr88 .... Welcome aboard.... without a picture to be certain, the above explanations are reasonable, and likely accurate. Cheers, RickO

@Kkathyl said:
I actual like the Flow lines on some older coins, It give character.

I agree Kathy

@Treashunt said:

@Gunnr88 said:
What causes a modern clad coin to have stretch marks or wrinkling across surface?

old age, like people

I resemble that remark....