I am trying to figure out a way to fill a soccer ball with a mixture of cornstarch and water. I am very unsure if pumping it would work, as I suspect the unusual properties of this substance would keep the pump from working. If easier, filling a small inner tube would be a possible alternative. Any suggestions?
What are you doing with it. Could you just cut a hole in it, fill it, then patch it?
Any problems with funneling the required amount of cornstartch in through the airhole first, and the water second?
I’ve thought of the patch method, but would want the exterior to be as sound as possible. This may turn out to be the only way. Pouring in the cornstarch and then the water would work with an innertube, but not with a soccer ball. Barring any strokes of genius, I will have to use one of these two methods. Thanks for the suggestions.
Many soccer balls are made of a reinforced rubber ball with outer panels glued in place over it. You could pry off one of the panels and cut a small slit (say about 1" long) to fill the ball, then glue the panel back in place with a suitable adhesive. There are some really strong, flexible glues used for shoe and boot repair which would probably work admirably.
May I ask why you want to fill a soccer ball with cornstarch and water? Not snarky, just curious.
May I ask why you are doing this?
The OP’s apparently looking to make a non-Newtonian fluid. Water and cornstarch make a really odd substance that is impact resistant, but can still flow like liquid. The TV show Mythbusters made up a huge vat of the stuff a few episodes ago, and Adam was able to walk on its surface, but if he paused, <gloop!> he’d sink.
Inside of a soccer ball, I can only guess the net result would be broken toes when someone kicked it.
Another use for non-Newtonian fluids that’s being tossed around is armor - it might be usable as flexible and comfortable body armor, as an example.
Well, I can’t really get into the details of why I want to do this, but since I’ve been asked, here goes…
I have been helping someone who is trying to perfect a device for eliminating all instability on a platform that is in a vehicle moving over uneven terrain. Nothing in any way nefarious, but I have promised not to discuss details. The device needs to be able to sense and compensate for low and high frequency vibrations in order to precisely maintain its ability to do the same task repeatedly virtually error free. (This is very difficult to explain without getting into specifics, sorry if it seems purposefully vague. 
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The problem is that impacts from a vehicle hitting bumps in a road are too high frequency and need to be made into low frequency movements. So far he has mounted the device on a platform that is basically two metal plates with springs separating them to absorb the worst of the shocks. The problem is that the action of the springs tends to create an oscillation, so that the bouncing of the springs becomes difficult to correct for. He is looking for a way to have the springs “give” only once, not bounce repeatedly. My idea is that a non-newtonian fluid filled bladder sandwiched between the plates would allow the springs to give, but then solidify and stop rebound.
This is in no way a high dollar enterprise, so for a cheap experiment I thought a soccer ball or small inner tube filled with cornstarch and water would be an easy way to see if this is an avenue worth exploring. Sandwiched between the two metal plates, I thought the desired effect might be achieved. I want the bladder to be as tough as possible (so as not to potentially risk damaging valuable equipment by leaking), cheap, and relatively easy to fill so the mixture can be modified in density without a huge delay. Time is not really that critical, but I want to be able to try more than one density before the inventor’s hummingbird like brain flits on to another idea.
I would like to conclude by apologizing again for the vagueness of this explanation, and to assure everyone that this is in an effort to improve a very benign invention which will not harm anyone, win any prizes, or even improve anyone’s life significantly. Just trying to help a mad inventor who is a blast to help.
Instead of a soccer ball why not use something like this:
These fit inside automotive coil springs, which you can get very cheap at a junkyard. They have a tube and valve for filling. It would be much easier to get the corn starch and water inside one of these than to get it inside a soccer ball. The springs hold them in place so there is no need to specially construct anything to keep them positioned.
Just a thought.
It’s a good idea, but those are too big. A much smaller version might work. This could easily be a wasted effort, so I think I’ll try the inner tube, possibly via patching, to see if there’s any value in it.
Why patch an inner tube? Remove the valve core and fill it. screw the core back in. Tractor tires are water filled, though there are additives. There is also glutenous tire sealer that is poured into tires, to make them self sealing.
If you can get your hands on an old soccer ball they were made by stitching rigid leather panels around an internal bladder. Remove panel, remove bladder, fill with cornstarch mix, replace panel. The last part might need good glue. The stitching on those old things is very tight so I can’t imagine you would have too much trouble with your mix leaking.
How about one those hot water bags that you use in bed? Those are normally very sturdy.
And quite frankly, a beach ball inside a couple of garbage bags should be leakproof enough and very easy to fill through the larger valve.
A hot water bottle would be ideal, as the opening is very large, but they are sadly too small. I need something about 9 inches around and 4 inches thick.
I tried pulling the valve core on a 10" inner tube today, sadly the result was near total failure. Couldn’t get the cornstarch down the valve as it had a bend in it, so I tried pouring it in premmixed. The mix needed to be too liquid in order to pour, so I needed to add more cornstarch. Decided to cut a hole and add cornstarch, then add the water after patching it. The result was OK, but because of the placement of the valve it was impossible to bleed the air that was left inside. A bit frustrating.
Patching a soccer ball may be the answer. I’ll add that once I’ve removed the panels from the inner bladder there will be no need to replace them. Thanks for all the suggestions.
Don’t automobile shock absorbers do this?
I am not positive, but I think they are working in conjunction with independent suspension and leaf-springs. They are also much larger than the 4" height being sought, and using four of them would be too heavy. i imagine remote control cars have something similar, but I’m sot sure if they could bear the roughly 150 lb. weight. Certainly some kind of small spring-surrounded shock might work, if they were cheap and readily available.
Shock absorbers don’t support the car. Despite their rather misleading name, their mission is life is to absorb shocks. 
Four inches is way to short for a auto shock, but ATVs have shocks, bicycles have shocks (sometimes combined with a spring all in one unit) as well as other devices.
Well, not quite. The springs and the mass of the car form a resonant system that oscillates at some natural frequency. The shock absorbers are dampers used to control the magnitude and duration of the oscillation.
Yeah automobilte shocks are too big but something along those lines might be available or could work. As *Rick said, the shocks don’t support any weight, the springs do that. It’s just a suggestion and the equipment for it might not be available.
I’ll echo the “remove panel, cut small slit into bladder, fill with goop, patch slit, replace panel” sentiment, with one comment:
Get a bike tire/inflatable water equipment patch kit. They have self-vulcanizing patches that will easily patch a 1/2" cut in a soccer ball.