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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Patching TPU innertube
Date: Mon, 23 Dec 2024 07:37:22 -0600
Organization: Yellow Jersey, Ltd.
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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.

-- 
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971