How do patches work?

[[email protected]]

I patch tubes often with good results, but it belatedly occurred to me
that I haven't the faintest idea what I'm doing.

"Glue" below is shorthand for "cold vulcanizing fluid," which may not
be the same thing.

The ritual, as practiced by my sect, is:

1) Clean and smooth the area to be patches with sandpaper, buffing
solution, light scraping, or even more desperate measures.

Is the glue so delicate that even a little mould release powder or
grime from the inside of the tire will cause it to fail?

Is the glue so feeble that the tiny ridges defeat it?

2) Slather some glue on the area to be patched and wait five minutes
until it dries to a "tacky" state.

How much glue? Is a thick layer better, worse, or immaterial?

If waiting 5 minutes is good, is 8 or even 10 minutes better? What's
happening as the glue sits on the tube? Is it doing something to the
rubber, or is it just changing itself? Is it ordinary glue (or cement,
whatever that is), or something utterly different? Should I be ashamed
to call it glue instead of cold vulcanizing fluid?

3) Peel the cellophane or plastic or whatever it is off the patch and
press the patch onto the "tacky" spot.

What's the cover for? Just to keep the patch clean, or to cover some
special stuff that reacts with the "cold fluid vulcanized" area, like
a two-part expoxy? Could you just slap the patch on upside-down and
get the same results? The "right" side of the patch is usually a
different color.

Does it matter how hard you press the patch onto the tube? It's often
said that the roller tools are really just for mooshing air bubbles
out from under big automotive patches. Does pressure matter, or can
you just smooth the patch down gently with one finger?

4) Wait until tomorrow for the patch to "cure" in place.

I'm in no hurry, but what's happening? Are volatile chemicals slowly
evaporating? Is some slow chemical change taking place? One hour? Four
hours? Twelve? Is my habit of waiting until the same-time-tomorrow to
inflate the tube and look for more punctures overkill? Or would the
patch be even stronger if I waited _two_ days?

5) Would some rubber cement stolen from an office desk drawer and a
piece cut out of an old inner tube work just as well? Would it matter
if I tried to patch a natural latex tube with a chunk of synthetic
butyl, or vice-versa?

6) How do those quick glueless patches work, the ones that look like
clear plastic? Are they the same thing, or an entirely different
process?

***

As I said, my patches work well enough. I'm just wondering about the
really trivial technical details of whatever the hell I'm doing.

Cheers,

Carl Fogel

 

[Christopher Harrison]

I can't answer all your questions, but -- as far as I understand it --
the "glue" changes the structure of the rubber on the tube. When it
makes it tacky, the rubber has the structure that will allow it to
bond with other rubber (i.e. the patch): kind of like Velcro. When
it's curing (I never do this: it seems fine immediately after), the
glue and two rubber surfaces set together; hence sealing the hole...
As such, I would imagine that you don't really need much glue at all;
just enough to cover the surface of the tube where the puncture is.
Don't take my word on the above. Someone who knows what they're
talking about will no-doubt correct me!

Christopher

 

[Brian Huntley]

On Jun 11, 4:11 pm, [email protected] wrote:

> Is the glue so feeble that the tiny ridges defeat it?

> 3) Peel the cellophane or plastic or whatever it is off the patch and
> press the patch onto the "tacky" spot.

> 5) Would some rubber cement stolen from an office desk drawer and a
> piece cut out of an old inner tube work just as well?

1) The ridges defeat the mechanical seal, not the glue itself.

3) No, you peel the FOIL side off. The plastic or wax paper covering
is on the top of the patch - I leave that on until I'm ready to use
the tube, personally.

5) Rubber cement works, based on my experience. Using an old bit of a
tube would likely work, too, but it would be thicker than a normal
patch, causing a 'constriction' when inflated, and would also have
'square' edges that would cause tire <-> patch friction, it seems to
me. Proper patches are a dime each at my LBS and very thin.

 

[Ben C]

On 2008-06-11, [email protected] <[email protected]> wrote:
> I patch tubes often with good results, but it belatedly occurred to me
> that I haven't the faintest idea what I'm doing.

Neither have I but I will "answer" your questions with my own
superstitious opinions anyway

> "Glue" below is shorthand for "cold vulcanizing fluid," which may not
> be the same thing.
>
> The ritual, as practiced by my sect, is:
>
> 1) Clean and smooth the area to be patches with sandpaper, buffing
> solution, light scraping, or even more desperate measures.
>
> Is the glue so delicate that even a little mould release powder or
> grime from the inside of the tire will cause it to fail?
>
> Is the glue so feeble that the tiny ridges defeat it?

It usually works OK if you skip the surface preparation if for example
you lost the bit of sandpaper in the repair kit.

> 2) Slather some glue on the area to be patched and wait five minutes
> until it dries to a "tacky" state.
>
> How much glue? Is a thick layer better, worse, or immaterial?
>
> If waiting 5 minutes is good, is 8 or even 10 minutes better? What's
> happening as the glue sits on the tube? Is it doing something to the
> rubber, or is it just changing itself?

I assume that what's happening is that a solvent in the glue is
evaporating. Wait too long and it might dry out, not long enough and the
solvent won't have anywhere to go so the glue will never set properly.

That's how most glue of the kind that just comes in one tube works, as
opposed to the kind that comes in two tubes that you mix together.

I usually can't be bothered to wait 5 minutes so blow on the glue/stuff
instead, which makes it go kind of cloudy. This passes the time and
seems to work acceptably.

> Is it ordinary glue (or cement, whatever that is), or something
> utterly different? Should I be ashamed to call it glue instead of cold
> vulcanizing fluid?
>
> 3) Peel the cellophane or plastic or whatever it is off the patch and
> press the patch onto the "tacky" spot.
>
> What's the cover for? Just to keep the patch clean, or to cover some
> special stuff that reacts with the "cold fluid vulcanized" area, like
> a two-part expoxy? Could you just slap the patch on upside-down and
> get the same results? The "right" side of the patch is usually a
> different color.

I think the cover just keeps it clean. Repairing tubes with bits cut out
of other tubes never seems to work very well though.

> Does it matter how hard you press the patch onto the tube? It's often
> said that the roller tools are really just for mooshing air bubbles
> out from under big automotive patches. Does pressure matter, or can
> you just smooth the patch down gently with one finger?
>
>
> 4) Wait until tomorrow for the patch to "cure" in place.

I never do that.

> I'm in no hurry, but what's happening? Are volatile chemicals slowly
> evaporating? Is some slow chemical change taking place? One hour? Four
> hours? Twelve? Is my habit of waiting until the same-time-tomorrow to
> inflate the tube and look for more punctures overkill? Or would the
> patch be even stronger if I waited _two_ days?

I don't know but the time it takes to put the tyre and wheel back on is
usually enough.

 

[Michael Press]

In article
<7beee042-dcf4-470a-a709-39e95d3c9b53@m36g2000hse.googlegroups.com>,
Christopher Harrison <[email protected]> wrote:

> I can't answer all your questions, but -- as far as I understand it --
> the "glue" changes the structure of the rubber on the tube. When it
> makes it tacky, the rubber has the structure that will allow it to
> bond with other rubber (i.e. the patch): kind of like Velcro. When
> it's curing (I never do this: it seems fine immediately after), the
> glue and two rubber surfaces set together; hence sealing the hole...
> As such, I would imagine that you don't really need much glue at all;
> just enough to cover the surface of the tube where the puncture is.
> Don't take my word on the above. Someone who knows what they're
> talking about will no-doubt correct me!

Butyl rubber is a cross-linked polymer. It is impervious
to chemical transformation short of outright destruction.
Patch glue works by surface adhesion. Glue adheres better
to a clean surface, but it remains a physical bond, not
a chemical bond. Peel a patch off a tube and observe that
the surface of the tube is chemically unchanged.

--
Michael Press

 

[Dan O]

On Jun 11, 2:54 pm, Ben C <[email protected]> wrote:
> On 2008-06-11, [email protected] <[email protected]> wrote:
>

<snip>

>
> > 2) Slather some glue on the area to be patched and wait five minutes
> > until it dries to a "tacky" state.
>
> > How much glue? Is a thick layer better, worse, or immaterial?
>
> > If waiting 5 minutes is good, is 8 or even 10 minutes better? What's
> > happening as the glue sits on the tube? Is it doing something to the
> > rubber, or is it just changing itself?
>

<snip>

>
> I usually can't be bothered to wait 5 minutes so blow on the glue/stuff
> instead, which makes it go kind of cloudy. This passes the time and
> seems to work acceptably.
>

It's more fun to ignite the glue and watch it burn out, then apply the
patch immediately. (Thick layer burns longer, leaving the tube
hotter

 

[Leo Lichtman]

"Dan O" wrote: It's more fun to ignite the glue and watch it burn out,
(clip)
^^^^^^^^^^^^^^^^^^^
That used to be a common practice in the old automobile inner tube days,
before "hot patches" came into use. The people I remember doing this also
used to spit on the curb and then and then sharpen their pocket knives. The
ones who chewed tobacco didn't generally do this at the same time.

Someone should invent a hot patch/ CO2 inflater combo for bicyclists who
don't care how much their tools weigh. I can't recall ever hearing of a hot
patch that didn't hold.

 

[NStuart]

OK, how about putting a bicycle patch on the ripped bit on the vibram sole of your hiking boot -- because shoe-goo doesn't work? Will the cold vulcanizing effect work on different types of rubber?

Has anyone tried this?

 

[Froze]

You asked a lot! So lets start in order.

#1) you don't need buffing solution nor do you need to scrape the tube; you do need to buff the tube with the included buffer most patch companies provide. I happen to like using emery paper vs a steel buffer some companies give you. Buff the shine off the tube in an area slightly larger than the patch will cover with the hole in the center of the buffed area. Do not touch the buffed area with your fingers.

#2) Use only a thin layer of glue and spread it over an area slightly larger than the patch will cover, then wait for it to dry, around 5 minutes is good waiting longer does nothing. You can tell if the glue is dry by touching the outside edge with your fingernail to see if it's still tacky, (remember don't touch the glue, but the edge is where the patch won't be because you spread the glue an area slightly larger than the patch will cover! thus touching that area won't effect where the patch will be).

#3) Peel the foil off the patch and press the patch on has hard as you can between your thumb and fingers leaving the cellophane top on. The cellophane top can be either peeled off after the patch is on real good or left on it won't hurt the tube or tire leaving it on.

#4) you don't have to wait more than the original 5 minutes for the glue to dry and the pressing on of the patch, you can then insert the tube into tire and mount the tire and ride, there is no need to wait for the patch to cure overnight...but you won't damage or weaken the patch if you do wait.

#5) Yes rubber cement works on butyl tubes, no rubber cement does not work on latex tubes. Latex tubes require a different process, you need to make your own patches out of an old latex tube by cutting small 100mm or so round (not square) patches out of a latex tube. Use tubular rim glue and NOT rubber cement to glue the patches by buffing like explained in #1, and then putting the glue on like explained in #2, BUT you also need to apply a thin layer of glue on the patch itself, another BUT, but do not allow the glue to dry like you do with butyl, instead place the patch on the tube as soon as you get done putting the glue on and press firmly and flat.

#6) yes and no. Yes, good quality glueless patches like the Park and Specialized work fantastic, but poor quality ones like Skabs and others work horrible. The instructions for preparing and applying a glueless patch are the same, buff an area larger than the patch, peel of the backing and place on tube, press as firm as you can for 30 seconds then look at the clear patch...if the patch has any frosty looking areas you need to press those areas as firm as you can for 30 seconds. I've used nothing but glueless patches for the last 18 years or so and only my first patch ever failed, all the rest since then have never failed. I once had a 5 year old tube that was my main tube that had 13 glueless patches applied over those years and not one ever failed. People who hate those patches is only because they failed somewhere in the preparation stage. I even once had a person on another forum say that glueless patches won't hold past 120psi, so I purposely put a hole in a tube, put a glueless patch on, put the tube in a tire on a rim and place the rim in a trash can with my air hose connected and a remote trigger placed about 20 feet up so I could hide behind a car in case the rim exploded! and proceeded to put in 210 psi into the tube, I kept it topped of every day for 2 weeks and the patch never failed. I even taught a friend who swore against glueless patches by offering to patch a flat he got while we were riding, showed him how I did it, he rode on that tube for the rest of it's life and went out and bought glueless patches and he never looked back to glue on patches ever again. They are faster and you never have to discover a dried glue tube. I can glue or do glueless patches on the side of the road and ride on them immediately afterwards and never ever expect one to fail. However glueless patches do not work on latex tubes, they will hold for about 3 weeks or so then let loose.

Can you tell which patch system I like best?!