1. Wannabe gun whore
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Paintball welts

Im just wondering why paintball welts don't bruise in the midle why they just make a ring. Isn't it the unbruised part that gets hit first.

2. irc.zirc.org:6667 = chat!
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Here is my theory...

Bruises are cause by broken blood vessels. When a paintball hits you, it compresses the area of contact. All of the blood in the vessels at that spot is instantaneously pushed out of the way. The vessels cannot expand fast enough of wide enough in order to accomodate the sudden inflow of blood. So, they burst in a ring around the area of contact, where the vessels have only been compressed.

This sound 'bout right?

3. Of course it works-its AGD
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The center of the ball compresses into the ball. At a certain amount of exerted force applied to the surface of the ball due to impact, the ball breaks. Since the center impact area of the ball breaks into the ball, it impacts evenly over the contact area of the ball. This is fairly easy on the surface of the skin. The outer edge of the ball becomes a cutting edge once the center of the ball gives way. The remaining impact force of the ball falls on this cutting edge. Therefore, the total remainining energy contained in the ball all pushes on the tiny edge. Since the edge is thin, this means that the lbs/in^2 of force is very high, much higher than the initial impact force of the center of the ball.

Basically, the high force on the round cutting edge creates the ring welt we all know and love/hate in paintball.

4. AFTICA
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The above explanation sounds good in theory, but it doesn't hold up. I think the first one is the most likely.

Why do I say this?

I've been playing lacrosse for years, and getting hit with a lacrosse ball at high speeds leaves a "donut", a nice bruise-ring with an unbruised center, much like a paintball.

I don't know if the first explanation is entirely true, but in my experience it would make more sense than the second. A lacrosse ball doesnt have a cutting edge, and still leaves the same marks.

5. I love mechs!
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I think the welts that bleed slightly DID have that 2nd theory applied, but the bruise that comes is probably due to the first theory.

I KNOW the cutting ring theory works, b/c sometimes when I get hit on bare skin, I'm pulling tiny little bits of paintball shrapnel out of my skin and they are NEVER stuck in the middle of the impact area, but always in a ring around it where the nasty red ring appears.

SO a paintball welt is sometimes the combination of the welt (caused by compression, I think) and a ring CUT (cutting theory).

That's my idea anyway.

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I imagine that the blood getting pushed outward also plays a part in producing the ring as well.

The cutting edge I refer to is not necessarily a knife edge. It could be a blunt edge where a majority of energy is pressing on a small surface area. The ability of a paintball to cut is related to how much energy it takes for the shell to explode. If it explodes quickly, then the "cutting edge" doesn't develop. If the shell is too tough, the ball will bounce because there isn't enough energy in the impact to cause it to explode.

Thordic, the lacross ball collapses in much the same manner as a paintball. The center impact area of the ball collapses into the middle as it hits. The outer surface becomes an edge (although not sharp) and does not deform as much as the center of the impact. The difference is that the paintball eventually explodes to dispell the excess energy. The lacross ball does not.
Last edited by athomas; 04-26-2004 at 11:25 AM.

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supporting what's deemed #2 explanation (and the most prevalent), think in terms of the structural design of an i-beam. in a more empirical application, grab a 1"x4". if you lay it flat (1" high, 4" wide) across a couple of sawhorses, you can easily flex the board to breaking. if you were to mount it on edge (4" high, 1" wide), that same board would now bear your weight w/ minimal give. now, back to the paintball: the center is flat - easy to bend, while with the outside you're catching the edge - not in the cutting capacity (unless bare skinned), but structurally superior strength.

8. Team Eleven
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i think its because paintballs are magic and they do odd things...
Last edited by MadChild; 04-28-2004 at 10:49 AM. Reason: mispelled word

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MMmmmmmmm.....magic donut

10. Registered User
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Originally Posted by athomas
Thordic, the lacross ball collapses in much the same manner as a paintball. The center impact area of the ball collapses into the middle as it hits. The outer surface becomes an edge (although not sharp) and does not deform as much as the center of the impact. The difference is that the paintball eventually explodes to dispell the excess energy. The lacross ball does not.
Umm... aren't lacross balls solid rubber? 20cm cercumfrence 5oz. weight, seems pretty dense, if not solid.
Last edited by Fixion; 04-28-2004 at 01:30 PM.

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Lacross balls are solid rubber, but they do deform on impact. That's what makes a bouncy ball different from a round rock.

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lax balls

umm they also have a solid steel core don't they? although small

13. A.K.A Spanker
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this post looked familure.

a few months ago

14. Killswitch Engaged....
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Trust a guy who has taken too many physics courses to remember them all....

The energy from the impact is always, as a majority displaced at the edge of the surface contact. Think of when you fall down, or when you get snapped at by a lanyard. The energy displacement is primarily at the outside edges of the surface contact.

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