Making rubber pliable?

Is there a way to make some old hardened rubber more pliable?

I use hot water -- works good if the rubber isnt to old ---Roy

I soaked old rubber grommets in Armor-all, took awhile but helped a little

The effect will only be temporary, so if that's acceptable...

There's no way to permanently reconstitute rubber. Rubber never really stops "curing" kind of like concrete.

Boil it , it will become soft as jelly , you will need to wear gloves to work with it. Rubber gromets that held headlights on an old snowmobile had become hard as a rock, I boiled them and installed them with the headlight as easy as could be. Glycerine will help keep rubber soft afterwards

(quoted from post at 06:10:42 02/15/19) Is there a way to make some old hardened rubber more pliable?

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By any chance are you thinking about the rubber of a tire??

That would need a BIG pot to boil in.

Just buy new. Many service stations have vending machines in rest rooms. LOL

(quoted from post at 10:39:39 02/15/19) Just buy new. Many service stations have vending machines in rest rooms. LOL

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LOL Thanks for the morning chuckle.

(quoted from post at 07:39:39 02/15/19) Just buy new. Many service stations have vending machines in rest rooms. LOL

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Now, that gives me an idea for a new product. Hardened rubber, huh?

-Scott

Wilson ..... and at the same time a guy could pick up a spray can of WD40 for lubrication. Most service stations would have it on the shelf !!!

Can you give more details?

Might be some more practical solutions, but like others say, mostly only temporary.

More details:
I'm helping out on a project at a research farm in Florida where we are upgrading a system to pressure treat bamboo. The old system used a 20 foot vertical pipe to create the pressure whereas the upgraded system will use a solar powered small pump to create the pressure to force the boric acid mixture/solution through a pvc manifold that will handle 6 pieces of bamboo at once instead of only 1 piece in the old system.
The bamboo pieces are in 20 foot lengths and range in diameter of 2 inches to 5 inches and one end of each bamboo piece connects to the manifold by means of a rubber cap. We currently have a supply of various rubber caps in the sizes required, but some of them are now hardened from longtime storage.
I like the boiling idea as it is simple, but as mentioned earlier, it may only be a temporary solution.
I might mention that our demo/prototype experiment used a backpack sprayer to force the liquid through the bamboo and it only took about 90 minutes to get the fluid comiing out the other end. By pressure treating the bamboo, it lengthens it's usefulness from 2 years to approx 12 years as an outside building material.

Thanks for all the comments.

If you get triple life out of that set up, you might get 20 times more life if you put some real pressure to it.

Ethanol in gasoline should soften it up. I have trouble with gasoline doing that to rubber all the time.

Soak the rubber in silicone oil. The reason it gets hard is that natural rubber contains some etheric oils and these evaporate over time. The silicone oil will soften up the rubber.