HELP – Too hot iron – back side of double sided TPU floor melted

[torch]

Hi Matt,

Looks like i might have made a bit of a mistake with the iron being about 10-15 degrees too hot and trying to be thorough pushing out air bubbles – leading to me applying too much heat and damaging the TPU later on the underside of the floor.

What would you recommend doing to ammend? Will aquaseal be enough, or should I be ironing a layer of tpu over the top of the strip of damaged TPU (it’s the first seam of 3R).

Photos below. With a wide pic of scale, and close ups of the top and underside.

DIY Packraft – Floor TPU

Topic

[snack pack]

I’m having a bit of the same “problem” with the melt through, but have experimented a lot with the welds and the ones that burns through some is the strongest, so I am just writing it off as an aesthetic difference and love the idea of just slapping some extra fabric on the bottom of the boat.

 

[Blair]

I figure instead of starting a new thread I would tag onto this one.

I’ve been doing some testing and I can heat seal the tube fabric to the flooring (1000D I think), but the heat seems to be coming through a little to the underside of the flooring. If it put more tube fabric underneath the floor it kind of sticks, but in a way that there was clearly not enough heat and both sides pull away cleanly. The TPU doesn’t look at all melted, just heated.

I don’t think this is a problem, but I wanted to check to be sure. Is this fine?

[Matt (Admin)]

Hi Blair, it sounds fine to me. If it is 1000D then you should be able to get a good weld without permanently altering the appearance of the fabric – just move a bit faster. It takes some practice to get the timing right.

Paradoxically, if you can’t get a good weld before the heat transfers through and changes the appearance of the fabric’s underside, you might need to increase the iron’s temperature a bit.

Cheers

• This reply was modified 3 years, 11 months ago by Matt (Admin).

[Blair]

Thanks Matt, I figured it was fine but wanted to double check.

The iron is up to max, so I think I’m moving a bit slow, I suspect I may need more practice to find how quickly to move.

[Matt (Admin)]

When figuring out the temperature and timing, I find it helps to hold the iron in one place and count out five seconds, then remove the iron and roll (or press) the spot as it cools. Then check underneath for melt-through before ripping the weld apart to see if it’s bonded fully. If five seconds isn’t right, try six (or four, etc.). If no amount of time consistently lands you in the sweet spot, you probably need to adjust the temperature.

[torch]

thanks matt, that’s very reassuring. I’ll get to the end of assembly then decide on the best course of action.

[Matt (Admin)]

Hi – it doesn’t look too bad; I would probably just spread a bit of Aquaseal over that area, or seal a scrap of tube fabric over it if you don’t mind the look of a bit of yellow there (it’ll be on the bottom of the packraft, so not visible when in use).

It could be the temperature is too high, but it looks good elsewhere, so maybe just avoid lingering so long in one place. It’s tempting to heat a large area to work those pesky bubbles towards the edge of the fabric, but it’s easy to melt through the floor if you do it too long, so if the bubbles are small just leave them there (the seam is way wider than necessary for adequate strength), or use a needle to make a small hole in the tube fabric to release the air from the bubble (but don’t push the needle through both fabric layers or you’ll end up with an air leak).

[Author]

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