Reviving Old Hard Rubber Experiment

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I have a few pairs of old water/kayaking/outdoor shoes that I recently fixed a delaminating sole problem with Sonneborn NP1. This is a urethane adhesive/sealant that adheres to anything and forms a flexible bond. It even smells like milk chocolate! Only downside is a long cure time: About 24hrs.

With all soles now re-attached, I slipped yesterday on smooth concrete. Lucky I caught myself in time, but I began thinking about a method to revive the hardened rubber/vinyl soles.

Recently tried a product called ATP AT-205 (100% glycol ether),which is a non-petroleum-based seal conditioner. See HERE. Thought it may also do its magic here, so I applied it thoroughly to one sole, left it upside to sink in.

Then remembered I still had some Rawn Re-Grip (Methyl Propasol Acetate). This stuff is proven for refurbishing turntable belts, pinch rollers & belts in cassette decks and for making model racing car tires sticky again.

So RG went on the other sole.

Result? RG is the clear winner. Noticeable difference between the two. Feels like newer rubber. The hard, glazed surface is gone. 205 appears to not have done anything. Much better traction from RG'd sole on vinyl flooring than 205.

The rest of my rubber soles are getting Re-Gripped!

I'm going to try RG on wiper blades and some tough rubber suspension pieces just recently removed. Could be that just a yearly squirt of this stuff can greatly extend the life of rubber. Finally, noticed that Rawn makes a product called Re-Grip MIL that comes in 1, 5 & 55 ga. used for treating tires, conveyor belts, etc. in industry.

Don't know much about either ether or acetate chemistry. Perhaps a chemist or MK can chime in?
 
There are many types of rubber, and they have different chemical resistances. Natural latex, silicone, urethane, neoprene, on and on.
 
Interesting... I was going to post a question about affixing part of the sole of my one Birkenstock sandle. You answered that question for me! Thanks!
 
I threw out a set of Colorado boots last year for precisely that reason, rubber hardened, and I'm too old to enjoy the dog on linoleum feel.

Couldn't find anything on softening, and wasn't going to chase up slick softener.
 
Returning old hard rubber to its previous state is pretty impossible. The proper cross linking of the polyisoprene chains has been disrupted, and broken down, short chains get re-cross linked instead of the original longer chains. There's no way to re-lengthen the chains so any further cross linking just makes it harder. And any "un" cross linking makes it sticky just like it was before vulcanization.

This refers to natural rubber, I don't know about synthetics.
 
A few years ago I treated my front tyres (which showed sidewall cracking) with sunflower oil and later the rears with canola oil.

Idea was the cracks would get filled with polymerised oil and degraded rubber, which would slow further crack propagation. Seemed to work, in that the cracks were much less visible, but the oil also seemed to get absorbed by the rubber, which was a bit alarming.

Later I tried it on a radiator hose which had a crunchy feel, and that went away with one application. This was a bit more alarming, so I stopped doing it. Tyres look about ready for another treatment though.

It seemed the sunflower oil softened at least some rubbers, which I wasn't expecting.In moderation, this'd be a good thing, but one wouldn't want to overdo it with tyres. I don't know how or if it affected grip.
 
I've never understood what they mean by "drying out" when it comes to things like rubber, it's not as if there is water in the polymer that is somehow escaping. I suppose it refers to the cracking that comes from hardening and subsequent repeated flexing. The only thing you can really do for rubber is to protect it from oxygen (especially ozone) and heat.
 
I have successfully softened and reused the silicon gaskets found in car engines by soaking in lacquer thinner then Rislone..
 
Rubber is a blanket term just like plastic. Some formulations can be brought back to a degree by certain products and some cannot.
 
Originally Posted By: kschachn
I've never understood what they mean by "drying out" when it comes to things like rubber, it's not as if there is water in the polymer that is somehow escaping. I suppose it refers to the cracking that comes from hardening and subsequent repeated flexing. The only thing you can really do for rubber is to protect it from oxygen (especially ozone) and heat.


There's supposed to be protective wax in the tyre formulation, which migrates to the surface when the tyre flexes. I've seen it claimed/suggested that this is why inactive tyres on, for example, boat trailers, seem to suffer more cracking, because the surface wax isn't renewed.
 
Originally Posted By: Ducked
A few years ago I treated my front tyres (which showed sidewall cracking) with sunflower oil and later the rears with canola oil....Later I tried it on a radiator hose which had a crunchy feel, and that went away with one application. This was a bit more alarming, so I stopped doing it. Tyres look about ready for another treatment though.


Well, looks like that radiator hose just popped. Was warming it up to fiddle with the static timing and it started spraying green coolant around. I'm assuming/hoping its the hose and not a (head?) gasket, but it was a bit too hot to investigate closely.

I can't of course be sure the veg oil treatment caused this since it's an old hose on an old car, but its suspicious.

Might be tricky to find a replacement.
 
Hose seems intact, so the veg oil treatment isn't apparently implicated.

Leak might be from the hose junction with the thermostat, but I'll have to top it up and run it some more to find out.

Lot of rusty scale inside the hose, so a flush and change is indicated, though coolant conductivity readings were OK.
 
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