The best results I've had with heat sealing have been with a kitchen device used for sealing plastic bags of food. The makeup of this thing is a 1 foot long heating element wire under a strip of nonstick tape. The ag goes on top of tis and the cover closes over it, bringing a rubber gasket over the lenght of the heating element, and giving an even pressure to the bag. As you press the lid closed, a switch turns the heating element on. In 10 seconds you have a heat-sealed bag. I suspect there is a temperature control on the heating strip, or it just may be sized so that it does not get too hot.

To jerry rig something like this, try drilling two holes about a foot apart in a sheet of particle board or plywood and run your resistance wire through, so it lies on the surface of the board. Make your electrical connections underneath, and rig a foot switch. Cover this with a strip of teflon plumbing tape which is 15 inches long. That should overlap the heating wire by about 1.5 inches on each side. You hold the teflon tape in place by taping the ends to your board with some duct tape. The teflon should be pretty heat resistant, and of course, non-stick, but you may need to replace it occasionally, too.

To apply pressure to the seam while it is being melted, you can try using a board with a piece of foam window insulation -- similar to what is used for a hatch seal. Hinge the pressure board (with more duct tape?) to the board with the heating element, and try some scraps. You can keep the heat turned low and use a longer melting time, or you can turn the heat up and use a short time. Whichever you chose, put pressure on the seam before turning on the heat, and keep the pressure constant for 5 to 10 seconds after you turn off the heat. then you can open the pressure plate, and examine your seam. Do long seams in sections.

A friend told me that he had good luck ehat sealing plastic materials with a soldering iron or soldering gun. The secret (he said) was to cover the seam line with a strip of aluminum foil, which would diffuse the heat. I know that if you don't use the foil your soldering iron or gun, it will melt right through the plastic, and get all globbed up with melting and burning plastic as you try to slide it along the seam line. When I have tried using foil I have not had consistently good results. sometimes it works, and sometimes the heat is too high and it just melts through. At least i don't get the melting palstic on the hot tip of the soldering iron. A temp controlled soldering iron might work better. Achieving a good speed (not too fast and not too slow) when sliding the soldering iron along the seam might work, too.

If you are sealing an edge, you might try folding a strip of aluminum foil over it, and then using a clothes iron. This will give you the ability to apply pressure, and they have a temperature control. Play with the temperature range until you find something that works. The foil will keep the melted plastic off your iron and your workspace.

Now that I think about it, since I found a good glue for vinyl I don't think have made any further attempts at heat sealing it. I have been that happy with the glue.

good luck with this. let us know how it goes for you.

PGJ