tpu side

[Dave]

Packraft construction well underway. question..i’ve occasionally touched the exposed tpu side with my iron leaving marks. is this something i should be concerned with? the marks are generally very small, except one 1″ section that looks a bit fried.

Topic

[Ben]

Hi Matt,

Thanks for the reply.

I think Dave meant (correct me if I’m wrong Dave) that only the TPU coating was damaged i.e. the fabric and underlying PU coating were in tact.

I’m using a temperature controlled iron, so I don’t have any issues with melting the fabric itself. Only the TPU coating melts when I place my iron on it, and this is regardless of how long I leave the iron in contact for.

What I am concerned about – if my interpretation of Dave’s message is correct – is that water is able to leak through the fabric when only the TPU coating is damaged. If this is the case, this is a serious concern. The fabric I bought has a PU coating on the opposing side which I was led to believe would kept the fabric waterproof regardless of the integrity of the TPU coating e.g. loss due to melting, or thinning due to abrasion etc.

When I get a chance over the weekend I’ll be sure to test out my own fabric.

Regards,

Ben.

[Dave]

Hopefully I didn’t cause too much alarm with my question.  In my tests the minor stuff didn’t seem to leak, but a couple of the more majorly damaged areas did. When I say “leak”, the area appeared damp on the outside after a couple of minutes and then a bead slowly formed.

Probably I should explain how I did my tests. I took some scrap material and damaged it in a number of spots with varying degrees and types of damage. I folded and sealed the edges of the fabric to form a pouch with the tpu on the inside and filled it with water. Then I watched it for a couple of minutes. The leak formed slowly in a couple of places as described above. I wish I had done this a bit more scientifically to be able to explain exactly what types of damage caused the leak, however the lighter touches and strikes did not seem to leak. The other thing to consider here is that the actual packraft will be filled with air, and I suspect in the above cases water would not enter the raft, but more likely that air would escape (very slowly).

I’m hoping in my raft that it’s nothing that some sealant won’t fix in a few areas. I was going to truck along and after I inflate see if any of those areas are leaking air and then go about fixing them.

 

Dave

[Matt (Admin)]

This is a common mistake that I’ve made myself, as it only requires a moment of inattention to damage the TPU coating with a hot iron. In most cases it only leaves a small mark on the fabric that doesn’t affect it’s performance, but if the iron is left in contact with the TPU long enough, it can make a hole.

The best way to patch a hole of any size is with a scrap of heat sealable fabric heat sealed over top of it. Color matched scraps are included in the kits for practice and patches.

If you get a tear or puncture in the field, you can use repair tape or Seam Grip or Aquaseal.

For more info on this topic, check out the Punctures, Leaks & Repairs page.

Cheers!

[Ben]

Hi Dave. I’m currently making a packraft and have unfortunately damaged the TPU coating a few times now myself.

I am surprised to hear that water is passing through your fabric though, even with a damaged TPU coating…

To my understanding, the fabrics sold through Matt’s site have a PU coating on one side in addition to the heat sealable, TPU coating on the other. In which case, the fabric should still be impermeable to water.

Matt – are you able to shed some light on why this might be happening?

[Dave]

I did some tests with scrap fabric and found that damaging the tpu coating allowed for some water to creep through the fabric, so I guess I’ve answered that question. What I’m looking at now is how to correct it. I was thinking of applying seam gripper to these areas – I assume on the tpu side?

[Author]

Replies