evans G2 question

Sean117

Junior Member
so i just got some new heads, evans g2 clear, and there seems to be some kind of air pockets or something on the heads. is this normal?
 
It's a visual effect called "Newton Rings". I have a long explaination is anyone's interested.

Dennis
 
It's because it's a two ply head, it doesn't happen to single ply heads. They're not going to lay perfectly flat/together when they are put on the collar. Apparently there's a bit of a problem with Remo regarding this, not sure if Evans has the problem as well. But if the two plies aren't manufactured properly it can cause a "dead head", which is why you occasionally see people in the drum section holding up heads by the collar and lightly tapping them close to their ear. The theory is if you tap it and it puts out a slight tone, the head is good. If it doesn't, and it sounds papery or plastic in a sense, the heads aren't going to open up as well as they should. I've tried it and never noticed a bad head, but then again maybe I've been lucky. Some cats swear by it.
 
It's a visual effect called "Newton Rings". I have a long explaination is anyone's interested.

Dennis

Sure, I think I've read it before, but I could always use a refresher.
 
Newton rings occurs when two highly polished surfaces come together with uneven pressure. It sort of looks like and gets confused with oil between the plies of Mylar. I first saw this phenomenon years and years ago when doing darkroom work. Most of my enlargers had glass negative carriers, so there was always a problem trying to get both the shiny or base side of the negative and the glass in the carrier to have perfectly even pressure across the entire surface so these little rainbow patterns would not show up on the enlargement. By taking your finger across the head, you'll be exerting pressure on different areas of the two plies causing the "Newton Rings" to move and change patterns.

Dennis
 
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