Re: Patching TPU innertube

On 12/26/2024 9:20 AM, Roger Merriman wrote:

AMuzi <am@yellowjersey.org> wrote:

On 12/22/2024 8:30 PM, James wrote:

I got a snake bite puncture on one of my TPU innertubes.  I
haven't bought one of the commercial patch kits, so I
thought I would try a blob of Aquaseal.  Known for it's
usefulness in repairing neoprene stuff and more, I thought I
would give it a go.
>
I tried to rough up the TPU innertube surface, but the
sandpaper didn't seem to have much if any effect.  I cleaned
it with a little Windex, and after that had dried and I had
rubbed it some more with clean tissue paper, I applied a
drop of Aquaseal to each hole.
>
I have the stuff that takes about a day to solidify.  I left
the tube undisturbed for at least 12 hours, though I can't
recall exactly how long, before putting it back in the wheel
and inflating.
>
This is on my gravel bike, with 40mm tyres that I inflate to
40-45psi.
>
The repair has held for a few hundred kilometers at least,
and now I have put different tyres on the bike, so I
inspected the repairs.
>
The blobs of glue seem to have spread and flattened a bit,
but otherwise have appeared to bond well and not leaked.
>

>
Good choice. I knew nothing about the subject before
snooping around just now. It seems Aquaseal active
ingredient is methylenediphenyl diisocyanate which is
compatible to TPU polyurethane.
>
https://www.nrs.com/assets/downloads/msds/msds%202291%20aquaseal.pdf
>
https://polyurethanes.basf.us/files/pdf/2019-MDI-Handbook_EL.pdf
>
Making a reliable bond unlike a simple contact adhesive such
as a stick-on patch.
>

 Yup interesting stuff, I’d not persisted with TPU tubes, as on the Gravel
bike tubeless has solved that, and TPU seem to puncture just as easily as
butyl
 I’ve toyed with idea of the MTB as with that and it’s burly tires punctures
aren’t a thing, but on the other hand would one notice the difference with
a TPU tube in terms of feel?
 Hence I’ve chosen to not fix what isn’t broke for time being.
 Roger Merriman

"not fix what isn’t broke"
Good plan. Which is why I'm riding the current version of the 300g tubulars I rode 50+ years ago.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971