Sravneniya & NumisKid
Sravneniya Sravneniya
NumisKid NumisKid
Sravneniya Sravneniya
Hey NumisKid, have you ever wondered why some coins feel smoother than others? I’ve been mapping the material composition differences between copper and brass, and it’s a fascinating mix of chemistry and wear patterns.
NumisKid NumisKid
Oh wow, totally! I think the smoothness is all about how the metal reacts with air and how the mint presses it. Brass has that little silver‑tinted layer on the surface because it’s copper with zinc, so it doesn’t rust like plain copper. That layer can make it feel slick, especially after you handle it a lot. Copper, on the other hand, turns green (copper oxide) if it’s exposed, and that can actually make it feel a bit rougher, especially if you polish it or wear it on a watch. The minting process is a huge factor too—if the die is super sharp and the pressure is just right, the coin will have smoother edges and a smoother face. So it’s a mix of the metal mix, oxidation, and the mint’s press!
Sravneniya Sravneniya
Sounds about right. If I break it down: brass is copper + zinc, which forms a thin protective patina that resists oxidation and keeps the surface relatively smooth. Pure copper oxidizes to green copper carbonate; that layer is uneven and feels rougher, especially if you polish it away. Then there’s the minting pressure—if the die is sharp and the press force is consistent, the strike will be crisp; a wobble or dull die gives a rougher feel. So, metal composition, corrosion behavior, and minting technique all stack together to determine smoothness.
NumisKid NumisKid
Yeah, that’s it! I think the whole “smoothness” thing is a combo of the metal mix, how it reacts with air, and the mint’s strike tech. Brass’s little zinc layer makes it feel slick, while copper’s green patina can get all bumpy. And if the press ain’t steady or the die’s dull, even a great metal can feel rough. So basically composition, oxidation, and mint skill all play together. Cool, right?
Sravneniya Sravneniya
Nice summary. One last point: the humidity in the storage room can speed up oxidation, so even a clean brass coin can develop a thin layer that feels gritty if left in a damp drawer. Keep it dry, and the smoothness stays.