In my house amber natural rubber water tubing turns black and weakens in around six months. Ditto for O-rings.
I remember that water tubing in the lab used to stay amber for years and become hard and brittle before it weakened.
When I say "weakened" I mean crevices appear when you stretch the item and it severs easily under tension.
Does this suggest a particular contaminant in the air?
The items are not exposed to direct sunlight, but do get a little refracted sunlight.
Ken C
Ozone is a very common culprit. It will break the rubbe chains repeatedly so that the short chains can crystallize more easily. Crystalline rubber is not stretchy (ever try to stretch a diamond?)
Chlorine would be another option with similar results.
John Aspen Research, -
Opinions expressed herein are my own and may not represent those of my employer.
Is it the same rubber tubing? The tubing in the lab may have contained more antioxidants. Was the tubing in the lab made recently, while the one at home is several years old? How much chlorine was in the lab water, and how much chlorine is in the water at your house? Do you have a furnace fan motor (or other electric motors) that generate ozone?
Ernie
Rubber tubing isn't very good. So much more electrical stuff around generating ozone than ever before. Why don't you get some PVC tubing (Tygon, etc). Available at hardware stores. Not very expensive, much longer lasting and much stronger than rubber tubing. Richard
This sounds like ozone damage.
Sounds like biological attack, if I knew what I was talking about. ;>)
Depending on what is moving through the tubing you could choose silicone, hypalon, flexible PVC, even EPDM tubing as alternatives.
Nothing is moving through the tubing, which is used as the sling on a Hyperdog tennis ball launcher. See:
The stretchiness is the key property.
Ken C
The Hyperdog launchers are a blast. My two terriers go nuts over them. Coincidentally, one of mine broke just the other day.
Anyway, the tubing is cheap and will not last forever. Since the tubing and o-rings are exposed only/mainly to air, I would look at eliminating sources of ozone - pretty much anything electrical will generate ozone. Rearrange things in the garage some (I'm assuming that that is where you are storing these things) or try and improve the ventiliation. Garages don't normally have ventilation except for when the overhead doors are open.
John Aspen Research, -
Opinions expressed herein are my own and may not represent those of my employer.
Well, anything with a brush motor, anyway. If it _is_ ozone, it's doing the OP's health no good either--people being made mostly of polymer as well.
Cheers,
Phil Hobbs
An appropriate "slingshot" references:
- bug spray (deet or non deet, they both eat away at the tubing)
- sunscreen
- solvents
- oil
- gas
- diesel
- UV rays (store in bag when not deploying)
- wasp/hornet sprays
- pesticides/herbicides
- excess heat (ie; exhuast pipes etc)
just a few of the things that contribute to failures in sling tubing.
or just use the newer Nitrile rubber tubing.
I couldn't find seem to find references to repeated mechanical cycling causing discoloration.
David A. Smith
The culprit is likely to be the stretching. The tubing degrading faster is stretched extensively, while the water tubing in the lab probably was under a minimal stress. Stretched rubber bands degrade faster than unstressed ones. See also
Ernie
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