Chemical Engineers: How to Soften Rubber?

Discussion in 'The Garage' started by Bronco638, Feb 8, 2013.

  1. Bronco638

    Bronco638 Nobody Home

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    I recently read, on another forum site, that a 50:1 mixture of water to wintergreen oil, heated to just below boiling, will 'restore' old rubber (carburetor boots, etc.) to "like new". Another inmate there opined that a mixture wintergreen oil and toluene will accomplish the same thing.

    Is this really the way to "restore" rubber or are the chemicals basically breaking down the rubber and the interim state is simply close to the way the rubber was when new? I'm more curious that anything.

    TIA.
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  2. H96669

    H96669 A proud pragmatist.

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    I really looked at that last year. They were getting good results and maybe too good, leave it in too long and too much softening/expansion then they had to wait until it dried out and shrunk back to normal.:huh

    But you should know that there are special rubber greases that will do almost the same. May not work for badly damaged and dried rubber but sure good for slightly dried out stuff. Very good at preventing the drying and cracking, I have been using that for many years.

    Big tube was empty after 20-30 years and I found out how difficult it is finding that in Canada/US nowadays, had to order another 20 years supply from the UK. Cheap, less than $20.00 to my door for 500gr.

    Google Miller Red Grease....Castrol Red Grease or PBR Rubber Grease.Great stuff to rebuilt brake systems, fully compatible with brake fluids and best of all no silicones. The last is very important if your bike(s) has an O2 sensor and you want to lube any rubber in and around the fuel/air delivery systems.:wink:
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  3. Dave in Wi

    Dave in Wi Long timer

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    I've probably seen those same threads (on sohc4.net?). It would be interesteng to follow up with some of the folks that did this early on, it's probably been a year or two now, and see if the rubber is still pliable.

    EDIT: here is the thread I was thinking of. http://forums.sohc4.net/index.php?topic=29707.0
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  4. 74C5

    74C5 Long timer

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    It sounds like you don't really want to soften rubber. You want to return it to original durometer and elasticity.

    You can't, in general. As it ages, rubber loses the plasticizers that are incorporated into the chemical mix. Continued cross-linking sometimes also makes the rubber harder as it ages. This is the reverse of men BTW.

    You can soften rubber with different chemicals though. Naptha also works for some others, MEK. But, they're being partially dissolved if uncured.
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  5. Tsotsie

    Tsotsie Semi-reformed Tsotsi

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    +1
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  6. kantuckid

    kantuckid Long timer

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    Seems I read that glycerin was good to wipe down things like door seals on autos .
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  7. Bronco638

    Bronco638 Nobody Home

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    Yeah, I think that was the gist of the post I read. They were talking about bikes from the late 80s where those rubber pieces are 22+ years old now any are getting harder to find and more expensive.
    I figured as much. I guess the key would be to find some way to soften the rubber without causing it to breakdown and (eventually) fail.
    :d
    Got it, thanks.
    Actually, it was on a Honda VTR250 Interceptor forum site but I'm willing to bet the discussion what similar in nature.
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  8. H96669

    H96669 A proud pragmatist.

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    I used that again yesterday on some older rubber.
    http://www.millersoils.co.uk/scripts/tdsPrint.asp?prodsegmentID=267

    Different products....more specs, even a website on rubber greases. Just found that::wink:

    http://www.redrubbergrease.com/red-rubber-grease-msds-data-sheet-castrol-girling.html



    And for some reason, not well known in North America them rubber greases. Been through that somewhere else, sure was glad for some continentals that came on that thread and supported my views on such products.:rofl

    Not perfect but certainly helps to bring back some of the elasticity. I use it mostly "preventively", never had to replace too many,if any, rubber pieces where I used it.

    BTW, gave some of my stash to a friend, he really likes it. As a motorcycle restorer, he is quite familiar with dried out old rubbers.:wink:

    GM used to sell what we called "Latex" back in the days. Mostly used to maintain weatherstrips when they were still made with real rubber. Whitish liquid that somehow penetrated the rubber. But....that was back then, haven't seen that around for a very long time.:wink:
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