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I have had a number of Duotone sails split along the seam. Surffx have been good enough to repair them for me at no charge but that means a week without the sail while it's posted there and back or an hour and a half drive each way for me.
Is there any glue I can use to repair the seam? I don't have access to a heat welder.

I'm getting a bit sick of repairing the manufacturers defects. No, I never pump the sails above the recommended pressure. Why don't they double weld the seams? it would be a fraction more weight in the sail for more reliability.

Cheers

Yes, the duotone bladders are not great... Just as extra suggestion on the heat welder, you can also use the heat welder of the vacuum machine that you use for sous-vide cooking. So if you have a friend into that, give him/her a call

Sure the local kite repairer has a better solution
like fix or fit other brand bladder etc.

I have had good results welding bladders with a clothes iron. It takes a little practice to work out the settings and a process but then it's quite easy. I had a heap of old bladders to practice on.

I've done one with a split seam and a cross tear, and one with a full rebuild of the front of the strut.

A few tips.

I use non-stick baking paper to protect the bladder from the iron and to stop the bladder sticking to the table.

I use a straight edge to guide the iron and make nice straight welds.

I generally set the iron on maximum and weld with the edge. You end up with a nice welded groove that looks like a proper weld.

Place the iron on the work, move it at a decent pace, then lift it off. Don't press too hard. Don't stay in one place too long. You can always run it over the weld again if it's not stuck properly.

You can only weld a piece of bladder a few times before it become too hard and dense and won't weld any more.

You can't weld too many layers, for example when welding in patch you might get three layers coming together (top and bottom of the original fabric plus the bladder). It's doable but can take a bit of effort and a few tries.

It's often far easier to open up a length of the bladder, do a repair, then close it up again than to mess around with little patches and stuff.

Tear Aid Type A is great for small patches and leaky seams, and it welds ok. Also Stormsure urethane glue for smearing on leaky seams.

I'm not sure double welding really helps all that much. The inside weld is going to do all the work. If it fails the bladder's pretty much rooted. It's not like one weld is strong, two welds is two times stronger.

By far the worst thing is accidentally welding or melting a bit of bladder you didn't mean to.

Welded seams don't stretch. All the stretch is in the unwelded fabric. That means you can make a bladder narrower and the fabric will stretch the fill the space. You can't make a bladder shorter and expect it to stretch.

PS Once you start welding and re-installing bladders a few dozen times you learn why bladders are designed the way they are. There's all sorts of stress and abrasion going on at the front end of a strut, and stretched areas if the bladder sticks to the wing fabric during inflation.

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Gorgo said..
I have had good results welding bladders with a clothes iron. It takes a little practice to work out the settings and a process but then it's quite easy. I had a heap of old bladders to practice on.

I've done one with a split seam and a cross tear, and one with a full rebuild of the front of the strut.

A few tips.

I use non-stick baking paper to protect the bladder from the iron and to stop the bladder sticking to the table.

I use a straight edge to guide the iron and make nice straight welds.

I generally set the iron on maximum and weld with the edge. You end up with a nice welded groove that looks like a proper weld.

Place the iron on the work, move it at a decent pace, then lift it off. Don't press too hard. Don't stay in one place too long. You can always run it over the weld again if it's not stuck properly.

You can only weld a piece of bladder a few times before it become too hard and dense and won't weld any more.

You can't weld too many layers, for example when welding in patch you might get three layers coming together (top and bottom of the original fabric plus the bladder). It's doable but can take a bit of effort and a few tries.

It's often far easier to open up a length of the bladder, do a repair, then close it up again than to mess around with little patches and stuff.

Tear Aid Type A is great for small patches and leaky seams, and it welds ok. Also Stormsure urethane glue for smearing on leaky seams.

I'm not sure double welding really helps all that much. The inside weld is going to do all the work. If it fails the bladder's pretty much rooted. It's not like one weld is strong, two welds is two times stronger.

By far the worst thing is accidentally welding or melting a bit of bladder you didn't mean to.

Welded seams don't stretch. All the stretch is in the unwelded fabric. That means you can make a bladder narrower and the fabric will stretch the fill the space. You can't make a bladder shorter and expect it to stretch.

PS Once you start welding and re-installing bladders a few dozen times you learn why bladders are designed the way they are. There's all sorts of stress and abrasion going on at the front end of a strut, and stretched areas if the bladder sticks to the wing fabric during inflation.

Great if you do a video.
Are you welding a patch on (some tears are not straight)?
Any idea why bladder starts sticking to wing material and how to stop it? I wondered if salt but a rinse of fresh water through strut didn't help.

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patronus said..

...

Great if you do a video.
Are you welding a patch on (some tears are not straight)?
Any idea why bladder starts sticking to wing material and how to stop it? I wondered if salt but a rinse of fresh water through strut didn't help.

The bladder needs some slip to allow it to slide into place when first inflated. You get that by putting the bladder in a plastic bag with a little talcum powder.

It's also good to partially inflate the bladder and give it a bit of a shake and a massage to make sure it's sitting nicely.

If a tear is along a seam its highly likely to be straight. If it's not straight then you can design your repair so it's easy to do.

Patch repairs are easier to do with Tear Aid. You can cut the patch and the hole so they overlap nicely, and Tear Aid stretches a bit when inflated.

Nice thread my go to that I have posted elsewhere is the freezer bag welding tool, about 30 dollars I guess, maybe easier to use than an iron

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