Ball size and temperature

[Patron God of Pirates]

A question for the inhabitants of the Deep Blue:

Does temperature have any effect on the size of paintballs?

We hear allot about bore sizing, and matching paint to barrel. All paintballs are manufactured to .68 caliber, but we know there are slight variations from brand to brand. Those variations must be in the thousandths of inches (i.e. 0.682", 0.679" etc.). So, does the outside temperature at game time have any play on the size of the ball at that level? Has anyone tested this?

I plan on testing this myself if no one else has.

[thei3ug]

So very much YES. Humidity and temperature play a big role in paint size and breakability. Even if you just open the bag and size a few, they can change within that time frame depending on the weather conditions.

Unfortunately there is no set change per weather, as paintballs themselves are imprecise, change from batch to batch, ball to ball, age to age, and by exposure.

[Patron God of Pirates]

My quick (and piss poor) study revealed the same thing. I put one bag from a brand new case of RPS Marbs in the refrigerator, and another in front of a space heater on low. Each spent about and hour in these conditions (plus or minus 5 minutes).

Then I barrel tested them with my 10" Boomstick. I don't have a caliper, and I was only looking to find significant enough size change to effect bore / barrel match. The "Cold" balls tested the same as my room temperature marbs, passing through the barrel with a quick blow.

The "Hot" balls got outright stuck. Most required heavy exertion to blow through the barrel, some required a squeegee to remove them, and one broke.

I realize that the scientific merit of this study are niltch considering the number of uncontrolled variables and the amount of un recorded data (actual change in ball size, actual temperatures, etc.). At any rate, it did simulate actual conditions paintballs might encounter.

If it is the case that temperature can effect ball size (which is in evidence), then barrel / bore sizing is largely a myth.

[FactsOfLife]

Originally posted by Patron God of Pirates
If it is the case that temperature can effect ball size (which is in evidence), then barrel / bore sizing is largely a myth.

I wouldn't say it was a myth exactly based on this testing. What I would say is that it IS important to match your paint/barrel at the time you are using it. This is why the Freak System is so good.

Temps are cool and dry in the morning? That might be a tighter insert. Gets hot and muggy in the afternoon? Go bigger.

You still need to paintmatch for best accuracy. It does make it tougher if you only have a single barrel. If I was in that situation, I'd buy paint that was a little too small, and be able to keep using it if the conditions caused it to grow.

[Patron God of Pirates]

Maybe I should talk to Viewloader or 32 degrees about making climate controlled paint cases, tubes, and revy's. :)

[FactsOfLife]

Originally posted by Patron God of Pirates
Maybe I should talk to Viewloader or 32 degrees about making climate controlled paint cases, tubes, and revy's. :)


yeah, a humidor for paintballs...

I use a 60 quart Coleman cooler to store my paint in. works perfect.

[battlegroup]

The only flaw with the barrel test is friction. When you change the temperature of the ball you are changing the friction carateristics of the skin of the ball. That may be why the ball stuck in the barrel where the cold ones didn't The size may still be the same. Now, as tom has pointed for a good barrel paint match we want the ball to touch the barrel in only two places. this has everything to do with friction. If too much of the ball is touching there is way too much friction. if the ball is too small it bounces down the barrel. By heating the ball this coeficient of friction went up causing the ball to stick. So especially in higher temperatures we definetly want the good barrel paint match to limit the amount of ball touching the barrel therefore eliminating most of the friction.

Now with that said, I'm not saying that temp doesn't change the size of the ball. I have not done my own tests but I can tell you this. You can not pressurize a liquid. You can put pressure on it but you cannot pressurize it like a gas. This fact leads me to believe that temperature is not the culprit in ball expansion. Moisture is. As the ball absorbs moisture (and you've seen the balls from last week on the field that are huge in the cool morning) it gets bigger. I think balls absorb more moisture when the temp is higher and the humidity is higher.

If you take two days with the same humidity but different temps I think you would find almost neglidgeble difference in balls that started the same size.

Battlegroup

[Redkey]

battlegroup...


I doubt that any changes in friction would cause the balls to stick in the barrel.

You can pressurize both gasses and liquids. Perhaps you ment compress?



Correct me if I'm wrong here... but, isn't the paint in the ball slightly pressurized as the shell cools and contracts after molding? Heating the ball causes the shell to soften and perhaps expand a little bit from the slight internal pressure?

[xatle]

any time you heat something it expands, when you cool something it contracts.
this includes water right up to the point that it freezes where it expands once again as it chrystalizes.

[battlegroup]

How do you pressurize a gas? you compress it. Water itself is incompressible. You can pressurize it with a gas and it is the pressure of the gas that exerts its pressure on the water. the water itself is not pressurized because it is incompressible. if the paintball has gas inside then there may be pressure iside a paintball. if there is no gas then there is no pressure.

[battlegroup]

one thing i forgot to explain. When I said you can pressurize a liquid it works like this. you can pressureize a container of liquid but the liquid itself does not store any of the energy that is used to pressureize it. the pressure must come from the compressing of a gas. this pressurized gas exerts its presure through the liquid to the walls of the container because the liquid cannot be compressed. if you have nothing but liquid in the container then you only have no pressure. therefore when I stated you can't pressurize a liquid i meant that you can't pressureize liquid in a container if there is no gas present. if htere is gas in the shell of a paintball then you have a ball that is much more subseptable to variations in temperature.

second topic

I never stated that temperature doesn't affect the size of a paintball but i think that humidity has a larger affect on the size of the ball. Also the surface fo the ball becomes stickier when it is warmer. I have seen bags of balls that were fine when coming out of my house in the morning,stick together after sitting at the field forthe day. the barrel test for ball size is less accurate than calipers because with the rise in temp the shell friction seems to go up. the ball may be sticking because of this friction not change in size. only calipers will be able to tell if the ball size has changed.

do I believe the ball size changed. probably. But it may be that the elevated temperature allowed the ball to absorb more humidity (water) and this caused the ball to expand. I will attempt to do a test to see if changing the humidity but not the temp will cause a ball to expand/contract. I'll let you know what I find out.