Thanks. I'll keep at it & try that method. cheers.

No secret - it's just practice I'm afraid!  For PVC, the guns I use need the temp at 60-80% of the adjustment - PU needs 70-90%.


Like metal welding it's a combination of settings and speed.  I assume you've read THIS?  There are also videos on YouTube from membrane roofers who do this kind of thing all the time.  You should be rapidly rolling across the end of the moving gun as close to the tip as you can get (it creates a hot line at the welder tip and also allows some cooling behind the roller.  The gun nozzle flat "fold" line should line up with the material edge you are welding - if the gun is poked too far in you risk getting wrinkles as it pushes the material sideways.


With most PVC it will smoke slightly if you've got the temp and speed right.  If you stop it should smoke and melt the material - even dragging the tip across the material too slowly will leave a "slug trail" of melted material.  Flexible PVC has plasticiser in it to make it flexible - if you overheat it the plasticiser can evaporate leaving the material hard (the natural state for PVC) which isn't good for a skirt.


The material WILL peel apart BUT it should expose the reinforcing fabric - if it peels and there is PVC coating on both parts then either the welder was too cool (or moved too fast) OR the roller was too far away from the tip.
I've just welded a PVC skirt - took 4 hours to do the entire skirt (plus 6 hours to cut it out).  It'll take a day or two to remove the old skirt and fit the new one.  Welding is actually quite a bit faster than gluing as well as being more durable and cheaper!

I've purchased 2 of that type of welding kit. The first was adv. as a 240 volt,1500w, but, was a 1000 in reality. No joy from f/bay as seller vanished. Check sellers feedback first!  Another arrived today & had a 1600 W heating unit fitted. I've been playing with it & it's patchy. Some is really good & elsewhere peels off, even if the material, PVC 24oz, tarp, is well heated. What's the secret?  I've resumed construction as the summer heat wave is over, really was the hottest summer we've had for 30 years, & last year was the hottest recorded here! I've accomplished more in the past 2 weeks than I did so far this year.         I've watched vids on Y/tube about HH-66 glue being used with a heat gun. Any opinions?        By itself, applied properly, HH-66 came apart in several places after sitting in my ( hot ), shed last year. Blew out under lift pressure. . .cheers.                                                                 

This welding kit is the sort of thing you need with a better silicone roller.

Lighter colour skirt, welded seams and sacrificial glue coating across the contact line if using pvc material should be ok

Just thinking aloud here, given that the hot weather at Loch Fyne last year caused some skirt seam adhesives to melt, If I was to build a craft with a similar skirt in a hot country, what would the preferred method of jointing be? Welding I assume?

Thanks Steve and Al  Trade grip PVC ordered !

Tradegrip PVC - £14.50 : The Glue People!, Adhesives & Sealants UK




Probably a good idea to phone them, I've always found them very helpful.  I'm pretty sure this is the glue I used on my Sevtec skirts

Mike,
'The glue people ' do 'Trade grip pvc ' it's the stuff I've used for years. Renia do a similar glue.
You'd be better to weld the seams if you can, it's easier than you would think.

I'm thinking of buying some skirt material from a company called Rivertex. Steve Holland has done some comparison tests on it against pvc skirt material,  it's a lot more robust.

I'm sure its mentioned on here somewhere, but would someone be good enough to tell me the  name of the correct adhesive for my Sevtec skirt material And best place to buy ?  Final last weekend my son in law and I managed to move the two block and tackle to a position suitable to lift the hovercraft off the trailer. I can see a couple of small holes by the lift fan and seams that are beginning to part on the edges
Thanks in advance
Mike B