Uses For Old Silicone Caulking

[mindless1]

I have a few old tubes of partially used silicone caulking. Specifically GE Clear Silicone II if it matters.

It's WAY past the use-by date and doesn't cure. It's acid cure type and no acetic acid smell either. Very little smell of any kind. I put some on a pH test strip and it's ever so slightly alkaline. Otherwise it looks and feels exactly like silicone grease.

Has anyone repurposed their old caulking for other uses? Decent silicone grease is expensive, last tube of Raybestos brake grease I bought was near $20 for 8 oz.

The Raybestos grease is great stuff, but if I have serviceable old caulking lying around that's free? Granted I wouldn't want to use it on something with critical safety issues like brakes or dielectric for automotive electrical, but what about use as general purpose silicone dressing for rubber, or lubing sliding or geared plastic components?

Looking up rubber compatability (with silicone grease, not uncured caulking), most rubbers are compatible except silicone rubber, except that I don't know if any other chemicals in it, or the slight alkalinity would be a problem long term.

 

[Micrornd]

How did you store this caulk ?
All of my stuff seems to cure/harden when it exceeds it "use by" date.

 

[mindless1]

It's just sitting in my attached garage on a shelf. I've had latex caulk that dried out but this GE Silicone II tends to not cure when too old. There was no noticeable separation of the caulk that escaped the tube or is still inside, seems to be a consistent texture.

A few weeks ago I put a bead down on a scrap of wood as a test and it has not changed state at all in that time. Maybe instead of wood I should have put it on various materials then waited and checked for degradation of the material.

One thing I had wondered about is if acid is involved in curing, would it be suitable for outdoor applications where rain is slightly acidic or would there be a state change.

 

[Micrornd]

That's the exact brand I use/have, but as I said my results are the opposite.
I'm in FL, but it is stored indoor in AC/heated area, so maybe the humidity?
I'm at a loss to explain, but I guess it serves me right for the "maybe I should keep a couple extra tubes on hand, just in case" attitude when I live only 1 mile from several big box stores.

 

[Micrornd]

You could try "painting it with vinegar" as you can usually smell vinegar when using a fresh tube.
It may "kick" it enough it harden.

 

[mindless1]

I don't expect to ever be able to use it as caulking, not worth the hassle if it doesn't cure because it's a real PITA to clean off anything and get a good surface to come back and get good caulking to stick to. I'd read some suggestions to use vinegar to clean (fresh/good) caulking off but I tested vinegar and it doesn't do much to this old caulking. Also read about using acetone but meh, I think I'll just not use it in a situation where I need it to set up then it removes the need to clean it off if it doesn't cure.

These tubes did see high(ish)r humidity on some occasions since they weren't in A/C, and rarely saw temperatures below freezing and above 85F.

I'm still thinking applications as a substitute for silicone grease, but instead of laying a bead out on wood I should have put some on rubber and bare polished metal to see if the rubber swells or breaks down, or the metal corrodes. Granted in a metal contact scenario I'd be more likely to use a petroleum/lithium grease and "rubber" isn't just one formulation and by eye I can't tell the formulation of most rubbers... pretty sure I have some old remote controls or cordless telephone keypads that are silicone rubber which is potentially incompatible with silicone grease so I might test those.

 

[mindless1]

Hmm, now close to a month later the greae I put on the pH test strip in a thin layer has turned to a rubbery grease consistency. I don't know if it's the thinness or some reaction with a chemical in the test strip.

The bead on the wood, has the slighest skin on it but still grease consistency otherwise. This might greatly limit the applications, if it eventually sets but takes months to do so. It might still be viable for rubber dressing where a decrease in tackiness isn't always a bad thing, would attract less dust 'n grime.