Are you trying to soften rubber that's already cured (vulcanized) or to soften a rubber formulation to achieve a softer compound when cured? The latter is usually fairly easy, by plasticizer addition; the former is difficult at best. What type of rubber are you using (natural rubber, neoperene, etc.)?
I don't know of a way to do this without degrading (harming) the rubber. Generally, natural rubber will revert (soften and lose properties like tensile strength) upon over-curing or heat aging, so, theoretically you could apply heat to the rubber and it'll soften somewhat, but the surface may get sticky from excessive reversion and the strength properties will go down (along with the desired hardness drop).
Also, petroleum oils will generally swell natural rubber, so you'd have a volume increase along with a hardness drop and a physical property loss. Also, the rubber will very probably have an oily surface as the oil starts to bleed to the surface.
What application is the rubber you are trying to soften used in.....If it's what I think it is I can help....
Check out my website and you will see what I'm talking about.
Peter are U in the USA....? If so I can put U in contact with a source for something to soften tires.....If U are overseas I will have to look the chemical name and post it.
Peter....The most powerfull softener we use on kart tires is a product called "Goatpee" the chemical name is methylnaphthalene I do not recommend using it on car tires...I have no clue what it would do. Use rubber glooves and apply it in an open area, the fumes are not good to breath.
There are some much safer products available to soften and add grip to tires from a company called Track-Tac I think they could ship you some even overseas. There website name is
Kart86, thanks for your information. Yea, this is exactly what I need. What kind of store I can buy some Methylnaphthalene? Does people in karting mix their own tyre softner juice? I don't really want to buy the existing juice. I want to mix by myself and experience it. It should be fun. Do you know how should I start to mix my own juice? thanks
Peter, as Kart86 has intimated, if you use this juice anywhere other than outside you are taking a severe risk with your health. If you must use it, wear a high grade respirator mask. I, for one, wouldn't want to synthesise this chemical even in our very well equiped laboratories.
