Feel like I should know this...Worn Die? 0

[Woods020]

I see this periodically on moderns and have several times started to ask what causes it. Notice the “rough” areas on this quarter. It seems to always be around a raised part of the design. Is this just a severely worn die that doesn’t make the full metal flow in some of the low spots? Something else? 

I know this isn’t an error just curious as to what causes it for my education. Crappy photos I know but should serve purpose. 

[Conder101]

Thin film grease strikethroughs

[Woods020]

1 hour ago, Conder101 said:

Thin film grease strikethroughs

Amazing a thin film of grease can have that much impact. Thanks for the info.