Poor patch quality
 

I have patched bike tubes for 40 years. Often I remove a flat and find a tube with 6 or even 7 patches that worked well until a new flat occurred.

Now however, I find patches are failing. Possibly this is due to a bad batch of patches, but I doubt it. I often find a patch that does NOT leak around the perimeter, instead it leaks right through the middle of the patch, as though the patch material is made of paper. I am not talking about the self adhesive plastic patches here, I am using the standard patches with glue etc.

Anyone else notice this? Or did I just get a few bad batches of patches?

Oh yes, I also notice that cyclometer quality has substantially gone downhill as well, but that's another post.

oldbluejeans
iambaughman.com

I use Rema patches exclusively and have never had the patch itself fail, only the glue bond occasionally when I've tried to patch over a seam in the tube. Any chance that the item (glass bit, metal sliver, etc.) that caused the original flat is still in the tire and poked through the patch too?

I use Park glueless patches. I have never had one fail for the life of the tube.

I may give them another try. The first version (GP-1) years ago was known to fail frequently since the patch didn't stretch with the tube. I tried them and my experience confirmed their poor reputation as they were unreliable for more than "get-home" use so I never used them again. Maybe Park has improved them to the point of reliability.

The most-common problem with patches that slowly fail is that the patch allows stretch, which thus also allows the glued part of the tube to also stretch into a state of tension as the inflated tube fills the tire.
With the tube itself stretched in tension, the patch remains pinned against the inside of the tire casing by air pressure, but the tube can pull away from the patch, starting at the puncture hole, since air can only get between the bonded layers at the hole.
Eventually, as it slowly peels away, the tube is pulled into a flat surface, like a drum head, until the "drum head" diameter reaches the edge of the patch, at which point the air rapidly escapes.

The "speed patch" product, which introduced the idea of glueless patching, used a thin closed-cell foam sheet which was elastic, and these patches were known to fail reliably minutes or hours after each repair.
The subsequent Park product used a less-elastic plastic sheet material which by comparison was many times more inelastic, which helps prevent the tube from pulling away from the patch starting at the hole.

BTW, today's inner tubes are highly variable in terms of their patch-ability, with some tubes having a slightly "gummy" surface rubber which is extremely slow to abrade away cleanly, and all types of patches (glued and glueless) are challenged by it's Teflon-like adhesive properties.
By contrast, tubes from back in the day would typically abrade cleanly, with no balled-up, sticky rubber having to be sloughed off continuously as it was being created by the sanding action.

Could be, but not in this case
 

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You are correct HillRider that this could be a cause. I always check the inside of the tire though, so I am not sure that applies here. Where do you get the Rema patches?

Rema patch kits (a plastic box with a small tube of glue, sandpaper and 6 or so Rema patches) are available at most bike shops and from Bike Tools Etc. among many on-line dealers. You can also buy them in boxes of 100 for shop use or sharing with friends.

Here is Bike Tools Etc.'s web page for the Rema kits and the boxes of 100 patches are shown on the second page:

http://www.biketoolsetc.com/index.cgi

Yep, Rema patch kits are not the same as the cheap generic ones. I've had a few Road Tubeless tires that I simply could not patch with a generic/Park patch kit, yet the original Rema worked fine.

For road tubeless, Rema sells a patch kit with a different glue.
Ideally, the tire makers and Rema would fully cooperate on the issue of compatibility, but I don't know if that's actually the case, as it is with tubeless tire and rim makers co-generating standards of compatibility.

This may be true with patches that use 'rubber cement', i.e. the very cheapest generic patches. However, it's not true with cold vulcanized patches like the Rema. Cold vulcanizing goes beyond a simple adhesive bond and becomes part of the tube. The new bonds formed are almost indistinguishable from the original rubber. They won't peel away fromn the tube because they are part of the tube.

I've not run across any tube that is unpatchable and I have tubes from many different sources. All tubes, even the old ones, have a mold release compound on the outside. The tube couldn't be removed from the forming mold without it.

The key to a successful patch is more involved with the quality of the patch...*COUGH* Rema...and allowing the glue to dry properly than with the tube itself.

A leak through the tube sounds like the offending object hasn't been removed.

The only time(s) I've seen a proper Rema failure was due to the the puncture being larger than a couple of mms, and the patch eventually began to aneuryism/rupture. I stated in another thread where I'd "doubled" over a patch. This is when I did such, sucessfully. It's now SOP this type of puncture.

Mind y'all, Ccyco's admonition. For this reason I don't "grate." Besides, doing so scores the tube.
Who desires that?
Chemical buffer for me, or scraping+spit with a razor then alcohol cleanse if I puncture a 3rd time--which does happen...
...Or come-up with a thought-to-be-repaired spare that won't hold air :troll: *but only a little*

Remas (by me) have failed, due to operator error. This is why I have come to prefer them: they can be removed--carefully-- and another placed saving the tube for another ride series.

I do though let the patch "cure" for as long as possible. Usually more than a day (if I'm fortunate some weeks....).

Lastly, when in doubt, double down a second coat of glue. Might help, can't hurt.

I keep a stock of Rema patches in different sizes, so bigger tears are usually not a problem either, unless next to the vent. The repair kits tend to have just a couple of sizes. The larger patch sizes need to be bought separately and they might not be there at LBS-es.

Do patches get old and fail to properly adhere? I ask because lately I've had a couple that didn't seem to hold. They were a couple patches that I got out of an old kit because I needed larger ones. Could have been operator error, but my patch jobs usually hold.

I ask because a box of 100 Rema patches would probably take 15 years for me to use up. The ones that seemed not to work were probably 10 years old, although they were probably not the highest quality to begin with.

OBJ, Thanks for the post. I to use to have no trouble patching tubes but now I have no confidence. For me I patch exactly following the directions. Maybe right away or several days later, I install the tube and begin to fill with air. At about 60 psi or so, the patch will let go. I mean it's as if the tube streches but the patch don't. I have not tried Rema or Park Tool but will try both and both glued and glueless. The only patch kits sold here are Slime which is what I use. I also use quality Bontragger (sp) tubes from lbs.

The layer of rubber that contacts the tube is a mixture of unvulcanized rubber and one of a few suitable vulcanization ultra-accelerators. There's an activator in the glue, which activates the ultra-accelerator. The patch then vulcanizes itself to the tube. Patches can fail from age if the vulcanization gets kicked off, which can happen with high temperature, and which might ahppen at slow rate with time. There are probably failures where the ultra-accelerator breaks down and doesn't do its job.

Also, the point of sanding the surface of the tube isn't just to clean it, it's to provide a textured area, which gives the glued bond a lot more surface area, and makes it much stronger. Sand paper or emery cloth work much better than a cheese grater.

Does that activation imply that the glue needs to match the patch?? E.g. in Japan, patches and glue are marketed separately. For bigger tears you may e.g. buy a sheet out which you cut out a patch. Any shop will likely be offering a can of glue that can last for years without drying up. Myself I mix Rema and some quality Japanese products, but have yet to run into any problems.

Well, there differences between glues and between patches, and the stuff from one maker is designed to work with their other products. But there isn't that much difference between them, and the chemistries are largely compatible. I don't worry about it excessively. At work, where I do most of my patching, I have an 8 fl oz (250 mls, roughly) jar of cement that came from an auto parts place, and which gets used with Rema and other patches with success.

Are your tubes perhaps stretching greatly to fill the inside of the inflated tire? This would tug at the edges of the patch, so can eventually lead to a creeping failure of the bond surface.

How about your sanding procedure? Are you getting it sanded down to a very dark flat black? Are you fully sanding down the seam lines?

The glue is best applied with a piece of plastic bag stretched over your finger. Also, the glue needs to be fairly fresh, and needs time to etch itself chemically into the rubber surface. The glue should thus be spread initially in a thick enough layer, slowly so it doesn't go dry quite so fast, and the glue spreading should stop before the surface tacks up.

Lastly, never breath on the glue, the glue attracts and absorbs moisture that can compromise the bond (this is much better known in the auto/truck tire repair world).
Always allow plenty of time for the glue to dry completely before applying the patch, or the patches may fall off.

And, I'll say it again, some tubes have a gummy texture and do not abrade cleanly, even after much continuous sanding. Such tubes aren't the best candidates for repair.

Unfortunately quality if steadily going downward, and especially since China has come into making products. Cyclocomputers are not what they use to be, I think Sigma is the only one left still making a half way decent product but their customer service sucks. I'm sure if you spend $350 for computer it should be of substantial quality, but for most cyclists who buy the under $100 computer it's a problem. But it's not just cyclocomputers it's a whole gambit of stuff being made. It use to be 40 years ago Consumer Reports reported that the average household major appliance had a life expectancy of 28 years, today they now say 12 years! You go out and spend $1200 for an appliance just to to replace it in 12 years, to me that's nuts. And the world screams about pollution yet we have to replace appliances every 12 years so we now have to manufacture twice as many products then we did 40 years ago which puts more of a burden on natural resources and waste. And small appliances are a joke, you could buy a toaster 40 years ago and it would probably still be good today, you buy a toaster today and you'll be praising your God that it made it through the warranty period. My espresso maker only lasted 14 months as an example. TV's 40 years ago were rated to last 20 years, today 8 years. It's all about keeping our money flowing out of our pockets and into theirs.

Sorry for the soap box spew. Like you, said: for another post. But it matters I noticed this too.

Anyway, I would buy new patches, sounds like you got a patch of bad ones, get the Rema's if glue on is the only type you want to use. If you want to try glueless get the Speciaized brand.

[QUOTE=dddd;14686727]Are your tubes perhaps stretching greatly to fill the inside of the inflated tire? This would tug at the edges of the patch, so can eventually lead to a creeping failure of the bond surface.

Thanks for your comments. The tire size is an odd 28x1.75 or 700x45c but the lbs sales the closest tube 700x35-44c. It works but when I need to patch, I wonder if the tube expanding to fill the 45c circumference stretches past the amount the patch stretches and boom. If so, the same could be happening to op.

I used to race on 700X45 sized tires, and often found myself looking for the very biggest 700c tubes I could find.

I think that now some of the 29er-sized 700c tubes would probably fill out the inside of a 45mm tire nicely without any wrinkling or buckling.
To campare the actual width of new 29er tubes, always measure the tube's width with the deflated tube folded flat, and you'll then know which brand is likely a better fit in a 700X45c tire.
A 44mm folded width should easily fit into a 700X45 tire, even knowing that most 45mm-labeled tires are not actually that big.

When it comes time to install the bigger tubes, have some air in the tube, but not to the point of stretching it. You can later release a bit of air as you are prying on the tire, if needed, but the air volume will help keep the tube free of wrinkles during fitment.
The additional advantage of larger-sized inner tubes is that punctures lose air much more slowly, since the hole isn't stretched open. You might even be able to ride home before fixing a small puncture.

As I said before, stretching isn't a problem with a good quality patch because the patch isn't just adhered to the tube but actually part of the tube. Creeping of the bond isn't possible.

The glue should be applied directly from the tube and not manipulated after application. Just allow it to dry for as long as you can wait. You can't wait too long. Allowing the glue to dry overnight won't do any harm. Don't touch the patch with your fingers because it interferes with the bond. Water and water vapor shouldn't matter since the compounds aren't particularly water absorbent.

As mentioned, there are large variations in patch-kit quality, mainly with the composition of the patch and chemistry of the "glue". Do a test yourself by applying a patch, leave it on the bench for a couple days, then peel it off. The cheaper kits that use "rubber cement" mechanical bonding can be peeled off and the glue rolled off in little balls.

The higher quality kits, such as Rema and Camel use "vulcanizing fluid" that chemically bonds the two layers together with cross-links. There is no longer a separation or two layers; they are one. Trying to peel off the patch from these kits will result in tearing the patch and/or the tube in the process. The joint is just as strong as a single-layer of rubber.

After a couple of decades of doing these experiments, you get a feel for which patch-kits hold up better.

To deal with the stretching issue, I just pump up the tube to the same diameter it would be when it's inflated inside the tyre. Pour a drop of vulcanizing-fluid onto the centre of the patch and use that as a brush to smear the fluid over the hole and surrounding area. Wait 60-90 seconds to flash and press the patch onto the tube (pump it up again if it has shrunken during this time). I prefer this method because the 1st bits of glue are applied to the tube in less than a second from the last bits of glue. The drying time is the same. The painting-with-tip of glue-tube method many people employ takes too long and the 1st bits of glue are dried while the last bits applied is still too wet. Not to mention the uneven layer applied. And flakes of rubber inevitably finds its way into the glue tube and contaminates it. Causing the entire tube to be gone the next time you try to patch.

Some of you guys go through the weirdest antics just to put on a patch.

Just read this site: http://www.parktool.com/blog/repair-...er-tube-repairthe first section tells you how to use glueless patches, scan down to the second and it tells you how to do glue on patches. Both instructions say to use a alcohol pad to clean up the area on the tube after buffing, most of the time I don't bother unless my hands are really dirty. Notice the lack of weird ideas? no plastic bags, no gloves, no brushes, no stretching of the tube, no thick layers, and other blah blah ideas. Patching a tube is the simplest repair a person can do on a bike, it's not freaking rocket science.

So you wait until the stuff you put on last is dried. Big stinkin' deal. It is impossible to wait too long for the glue to dry. If you can keep it clean and dry, you can wait weeks to stick the patch on. The purpose of the solvent in the glue is to carry the solids, which are what do the work. Spread a thin even layer, using something other than the patch, let dry, and patch.

Firstly, even using Rema patch kits exclusively, the bond strength varies a lot, a long cry from the patch being "part of the tube".
I see creeping patch failures often enough even after all the proper instructions were followed. Many tubes don't give such good adhesion.

The only "manipulation" of the glue is to spread it around, hopefully with the solvent having a bit of time to do it's thing before becoming almost dry (why thickened glue doesn't work as well, but works acceptably if spread on thickly at first, giving more time to "etch" into the tube surface).

The rubber compound isn't "particularly water absorbent", but the solvent is, and the bond can be compromised (why auto patching instructions specifically warn against this, and most patch kits say "allow to dry", not "you may accelerate drying by blowing on it".

Heh, I actually once observed the tire-repair guy blow on the glue before applying the patch inside my truck's tire. The kids they hire! Good thing that the air here is so incredibly dry.

I have tubes in my tires and in my box o' tubes that have as many as 30 patches on them. I patch around 100 per year and I've been riding bikes for 30 plus years. If creeping patches were a problem, I suspect that I'd have seen some by now. The only patches that I've had fail have failed because I rushed the job and didn't allow the solvent to evaporate or I contaminated the glue by touching it. The fact that the bond is instantaneous and permanent is sometimes a problem if you don't get the patch oriented properly.

By 'spreading it around' with a piece of plastic you are manipulating it. Put it on, let the solvent evaporate, and stick the patch to it. That's all it takes and the patch is permanently in place. If you try to remove it, you'll likely rip the tube rather than pull the patch off. I know because I've done exactly that.

The solvent used is xylene or toluene. Both are highly hydrophobic and do not mix well with water nor absorb water. Yes, the instructions say to allow it to dry but that is mostly an admonition against doing something silly like setting it on fire or breathing the vapors or trying to use an air nozzle to blow the solvent away (with the vulcanizing fluid). I don't blow on the vulcanizing agent myself because the solvent will evaporate quickly enough without extra help but blowing on it won't hurt anything.

Edit: The Rema document on patching says not to blow on vulcanizing fluid with a heat gun because this will harden the surface and allow wet fluid to lurk under the surface. They also say to not use air from a compressor because the air is contaminated with oils which will interfere with the bond. I'd suspect that using polyethylene which is what most plastic films are made of could cause a similar problem.

Most agree that the solvent has changed over the years, but how do you know what it is?

Good to know about not using heat on the glue! I remember a guy who used a hair drier while patching piles of tubes at home.

WRT contamination from the surface of the plastic, any micro-layer of mold-release would not remain as a detrimental microscopic film, but would be miscible in the wet glue thus preventing it from having any significant effect on bond strength. Solvent-based glues are very good at dispersing any contamination "film" as long as the glue is agitated on the surface, and in any case the plastic wrap is not left between the tube and the patch. The plastic protects your finger while preventing skin detritus, moisture and oils from contaminating the glue.

You have to spread the glue around, else the glue would be dripping off the tube and the drying time would be enormous. Most patchers have noticed this I'm sure, that an even layer dries fastest.

Most tubes take well to patches and things become not so critical except for allowing the glue to dry, using fresh glue and not touching the patch. I typically use just a quarter of a patch for typical thorn punctures with lifetime reliability, but I do test the first patch that I put on any tube.

Its the glue its the glue its the glue.... Rema has about the best cold vulcanizing glue (so does Tractor Supplys Cats Paw or Monkey) but once you open the tube its all over... This is in-part a problem imposed by EPA regulations of Toluene... Because of high temperatures 90-100+ this is how I do it in Texas...

I buy cheap $1.50 patch kits knowing that once I open the glue its no good in two weeks - I keep an unopened patch kit in my bag for road use - After roughing out the surface I now clean the tube of with alcohol swabs or even patch glue then I put the glue on the tube and also the patch and let them sit till I can't stand it anymore - After a patch is put on I will wait a week before pumping up - If I have to use the tube immediately then I pump it up once in the tire and not before - Hope this helps...

PVC Cement for pipes works about three months, Superglue works about 5 days, Rubber cement 4 hours, Reagent grade Toluene after a Cyclohexane wash melts the two together leaving a weak spot on the tube, 3M Yellow Vinyl Gasket adhesive works permanently but turns hard...

The 3M glue needs further testing - I think that the 3M glue might just work all by itself???