Poor patch quality
09-08-12, 08:23 AM
#51
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This is correct. There are certain brands of patches you should use and avoid the other brands to be safe. Rema is the best glue on patches and glue available and have been for more then 40 years since I've been riding; and Specialized and Park have the best glueless patches available. Use any other brand of glue or glueless stuff and you're asking for problems.
09-08-12, 08:26 AM
#52
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This was the patch from the other day, Park brand.
Note that the other 3 corners had the same creeping failure, but I pressed on the patch which appears to have re-bonded those failed areas.
Notice also that the tube was buffed fully to flat black, down to the rubber, and that the freshly-peeled patch was repeatedly pressed on with real pressure.
The failures all started at the corners and worked towards the hole, which was not as big of a hole as appears here. A complete failure with air loss did not yet occur, yet from past experience I decided to have a look.
Tugging at one of the corners that I pressed back down shows that a re-bonding has occurred, yet the adhesion doesn't hold up to being inflated in the tire for a few hours.
Note also that this tube measures 26mm wide in a flattened state, fitted into a tire that was nearly, but not quite 27mm inflated width. This is a very normal, middle-of-the-road width ratio for high-performance road bike tubes/tires.
But this is all BS, I'm from the stupid generation, I wiped my forehead with the sticky side of the patch, blah, blah, blah.
Note that the other 3 corners had the same creeping failure, but I pressed on the patch which appears to have re-bonded those failed areas.
Notice also that the tube was buffed fully to flat black, down to the rubber, and that the freshly-peeled patch was repeatedly pressed on with real pressure.
The failures all started at the corners and worked towards the hole, which was not as big of a hole as appears here. A complete failure with air loss did not yet occur, yet from past experience I decided to have a look.
Tugging at one of the corners that I pressed back down shows that a re-bonding has occurred, yet the adhesion doesn't hold up to being inflated in the tire for a few hours.
Note also that this tube measures 26mm wide in a flattened state, fitted into a tire that was nearly, but not quite 27mm inflated width. This is a very normal, middle-of-the-road width ratio for high-performance road bike tubes/tires.
But this is all BS, I'm from the stupid generation, I wiped my forehead with the sticky side of the patch, blah, blah, blah.
09-08-12, 08:34 AM
#53
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No, you use just enough to put a thin coat evenly over an area slightly larger then the patch will cover, too much glue and it interferes with with the bonding. And by spreading it on slightly larger then the patch you don't have to worry about the edges of the patch not sticking. And due to the rough surface of the inside of the tire and the material it's made of the tube will never bond to the tire.
There's another reason that the TipTop patches won't bond to the inside of the tire. The Rema system is a 2 part system. The vulcanizing fluid contains one part of the bonding agent and the patch is coated with another part. Once in contact, the patch and the vulcanizing fluid start the process of grafting new rubber bonds onto the tube. The tire doesn't contain the part of the system that the patch does and, thus, won't form the same molecular bonding. The vulcanizing fluid may 'stick' to the inside of the tire but it's a weak bond.
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Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
09-08-12, 08:58 AM
#54
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I agree that you only need a thin coat of vulcanizing fluid, however a thick coat just requires a much longer drying time. It will still bond if it is totally dry but getting to that point may take a very long time. If you have the glue dripping down the sides of the tube, you've put on enough glue for a box of 100 TipTop patches
There's another reason that the TipTop patches won't bond to the inside of the tire. The Rema system is a 2 part system. The vulcanizing fluid contains one part of the bonding agent and the patch is coated with another part. Once in contact, the patch and the vulcanizing fluid start the process of grafting new rubber bonds onto the tube. The tire doesn't contain the part of the system that the patch does and, thus, won't form the same molecular bonding. The vulcanizing fluid may 'stick' to the inside of the tire but it's a weak bond.
There's another reason that the TipTop patches won't bond to the inside of the tire. The Rema system is a 2 part system. The vulcanizing fluid contains one part of the bonding agent and the patch is coated with another part. Once in contact, the patch and the vulcanizing fluid start the process of grafting new rubber bonds onto the tube. The tire doesn't contain the part of the system that the patch does and, thus, won't form the same molecular bonding. The vulcanizing fluid may 'stick' to the inside of the tire but it's a weak bond.
Probably why I saw people who used too much glue for a patch have a failed patch was probably due to them not waiting long enough for the glue to dry rather then interfering with the bonding process like I said, but maybe that's the same thing, but regardless, you explained it very well so we could understand it. You have been very knowledgeable and helpful on this subject. Two thumbs up!!
09-09-12, 02:16 AM
#56
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No problem, as long as the glue surface doesn't get contaminated by anything like dust. Remember, certain dust particles are attracted to certain materials by static charge or polar attraction.
I usually begin the drying by whirling the glued tube above my head, which shows rapid initial drying.
But, there are thicker spots where the solvent can take at least several minutes to even APPEAR dry, so a good long(er) drying has it's merits.
There is also the matter of the amount of solvent which permeates the tube rubber to the point of apparent swelling, but the visible symptoms of this appear to decrease within several minutes. The solvent is indeed quite volatile. Thinner tubes show a greater, more rapid dimensional change from the absorbed solvent, but appear to normalize within 5-10 minutes.
I usually begin the drying by whirling the glued tube above my head, which shows rapid initial drying.
But, there are thicker spots where the solvent can take at least several minutes to even APPEAR dry, so a good long(er) drying has it's merits.
There is also the matter of the amount of solvent which permeates the tube rubber to the point of apparent swelling, but the visible symptoms of this appear to decrease within several minutes. The solvent is indeed quite volatile. Thinner tubes show a greater, more rapid dimensional change from the absorbed solvent, but appear to normalize within 5-10 minutes.
Last edited by dddd; 09-09-12 at 02:21 AM.
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