Patch Kit Glue?
 

For many years I've been using Park Tools patch kits because that's what my LBS carries and I've been happy with them. I always carry a tube and the patch kit and when I have the rare (knock on wood) flat I usually use the tube and then repair the damaged one at home.

Today I went to buy a new kit and my LBS was closed so I went to REI and bought a few. When I got home a noticed that the Park Tools glue was labeled "Self Vulcanizing Fluid" while the Novara kit contained "Rubber Cement".

Two questions:
1. Are the two glues the same? Self Vulcanizing Fluid sounds fancy but the Park Tool kit is actually cheaper.
2. Is all rubber cement the same? (Don't laugh!) If rubber cement is all the same, I'll buy a big $1.00 bottle
from Staples or X-Mart for home use and save the small tubes for road emergencies.

Thank you.

That which is described as self vulcanizing tends to form a much more tenacious bond between
patch and tube, ie once cured the patch can't be pulled off the tube without some damage
being done. Rubber cement OTOH can easily be removed from patch/tube by comparison.
Vulcanizing type cement is recommended. The vulcanizing action only occurs 'rubber to
rubber' so using the cement on metal, wood, paper, it acts like ordinary rubber cement.
Non vulcanizing cement can be used for patching and will usually work adequately.

I just use a big jar of rubber cement at home and save the little tubes for road emergencies. I figure patches either work or they don't, and rubber cement works just fine, so the "better-ness" of vulcanizing fluid is lost on me. You can also buy Rema vulcanizing fluid in an 8 oz. can, by the way.

Thank you for your responses. I've learned something.

Rema Also sells boxes of the little tubes which, sealed, dont Gel Up .

+1 on using basic rubber cement. I happen to have a jar of Elmers at home and have used it to patch many a tube.

I've never repaired bike tubes using rubber cement, only the vulcanizing solvent. When people call this stuff "glue" or "cement" they're not being technically accurate. How it actually works is by chemically softening the tube, so the patch will become welded to it, so to speak.

It is analogous to welding vs. brazing metal. In welding, we're actually melting the base metal. The molten metals from both pieces mix, and when they cool, they've become one. With brazing, only the filler material melts. The base metal gets hot enough to bond with the filler, but does not melt. (Incidentally, the technical difference between soldering and brazing is the temperature involved, which is dictated by the kind of filler metal you want to use, which in turn is generally dictated by the joint strength needed.) That's enough for today's lecture.

Anyway, the reason you wait a couple minutes for vulcanizing solvent to dry is because it's not acting like glue to form a bond. It's dissolving the outer layer of the rubber, which combines with the soft rubber of the patch to be very strong.

People will pick the tiniest things to be "frugal" about.

Rema patch kits are already really cheap. That little tube of vulcanizing fluid can take care of over a dozen patch jobs if you're smart about it -- the key is to save up your punctured tubes at home, and the next time you need to patch a tube on the road, do that one, and then do the rest of your tubes when you get home before the fluid gels up. If you want to go big, Rema sells bulk quantities of patches. :thumb:

That's not how vulcanizing works. The vulcanizing fluid isn't softening the tube. You don't let the solvent in the vulcanizing fluid evaporate so that it will dissolve the outer layer of the rubber. You let the solvent evaporate because it interferes with the chemical process.

The vulcanizing fluid contains a accelerator/promoter in small quantities that acts on another compound that the patch is coated in. The two chemicals combine and start forming new chemical linkages between the tube and the patch through the dry vulcanizing fluid. They aren't "melted" together but are chemically bonded. The process will continue until the promotor and the active compound are consumed...a process that takes some time.

I would suspect that the two fluids are different. Rubber cement is a suspension of rubber particles in a solvent. For it to work properly, you should spread it on the two different surfaces, let the solvent evaporate and then put the two surfaces together. It sounds the same and is, in fact, the same process for patching a tube.

The difference, however, is what happens after the tube/glue and the patch contact. When using just rubber cement, all you are getting is the bond between the two tacky surfaces. The glue remains mostly unchanged. If you were to use a solvent on the glue and analyze it, it would look like the glue you put on in the first place. It's a bit like sticking two pieces of tape together. The adhesive is still the same adhesive on both sides of the patch/tube.

When you use a vulcanizing fluid, the process starts chemical reactions which form a stronger bond. Although it doesn't "melt" the tube or patch, it is closer to the welding analogy that Broctoon uses. The new bonds become part of the tube. A well cured patch should tear the tube if you try to remove it. A rubber cement patch probably won't.

I am of the opinion that a large reason that patch jobs fail for so many is because they are doing two things wrong. The main one is not letting the vulcanizing fluid dry long enough. I tell people while teaching them how to patch tubes that you can't wait too long. I've forgotten patch jobs for up to 3 weeks and had the patch bond perfectly. (This is why the vulcanizing fluid isn't "softening" the rubber of the tube.) Many people try to get the patch to stick to wet vulcanizing fluid and that just doesn't work.

The other reason that so many fail when patching tubes is because they use the wrong materials. They don't understand the chemistry and vulcanizing fluid looks a lot like rubber cement. Just because they look alike doesn't mean they work the same way.

So the vulcanizing fluid is essentially one part of a two part dry epoxy and the other part of the epoxy is already dry on the patch? I don't think I'd heard that before.

It's a two part system similar in the way it is used to epoxy but it isn't an epoxy resin. That's a different chemical reaction.

You aren't alone in never having heard this before. Many people don't know about it and thus think that they are using "rubber cement".

I'm going to keep using rubber cement because I already have a big jar and have used it successfully to patch dozens of punctures, but this thread has piqued my curiosity. After a bit of internet searching, I have not been able to find a definitive description of the difference between vulcanizing fluid and rubber cement, just people in online forums like this one claiming that they are different. I'm not claiming that they aren't different, I just can't figure out what it is about them that is different. The MSDS for Park Vulcanizing fluid actually lists the trade name as Rubber Cement. The Rema MSDS calls it vulcanizing fluid. Here's the MSDS for Elmers. I'm not a chemist, but as far as I can tell the vulcanizing fluids use naptha as a solvent where Elmer's uses alcohol. Is that the difference that causes the vulcanization? Seems like there should be more to it than that.

So what about latex tubes? Will the same glues work? I've heard of people cutting up an old latex tube and using that for patches, but I'd imagine they have to use different glues/cements/vulcanizers/whatever.

I'm not sure. I've read the same thing about latex tubes but I've never used one so I can't say for certain. A regular Rema patch might work because the same way but I can't say for certain either.

They all work if you clean both the tube and the patch first. Tubular rim cement seems to be popular, but that could just be tradition from the days when it was common for people to repair their own tubulars and that's what they had on hand.

Yes, ^^^^ Despite some claims to the contrary, regular bicycle patch kits work very well with latex tubes. I found that latex created an even stronger bond than butyl as long as the surface was prepped properly.

I tried using rubber cement. It worked on most of my patches, but my failure rate increased, so I went back to using vulcanizing fluid. I got a big can of it at the auto parts store. I did this not only for frugality. Once I open a little tube from a patch kit, it starts drying out. Next time I use it, I might find it to be empty, and the road is a bad place to find out. I try to avoid using those tubes at all.

Roll it up like when your rolling a toothpaste tube making sure all the air is out of the tube and screw the cap on tightly. I've had tubes last for several years this way.

One of my hard-and-fast rules is that I never pack an opened tube of vulcanizing fluid on the bike, only virgin ones. I don't ever want to repeat the experience of needing to patch a tube while on a ride, only to find out that the glue has dried up, again. ;)