Any heatgun will do, a reducer nozzle can be helpful; but is far from essential.tokebelokee wrote:What type of heat gun is used in the video? Also, are welds more brittle than the original molded plastic? Is there any way to anneal/heat treat/slow cool a weld to cut down on brittleness?
The trick is in learning to control the amount of hot air you apply, ideally the plastic's surface should look kind of sweaty before you start welding. But if the plastic is overheated it'll quickly discolour, (the second this happens at the surface you need to stop heating right away as it's chemically changing).
It is possible to do all of those things; Indeed when I split my Jefe, I heat treated a massive area of the boat that had been subjected to stress, and then fast cooled a section near the crack to hold it in the right (original) shape, then once the crack was welded I heated the boat up again and let it cool naturally (the rate at which plastic cools in warm air is more than slow enough to leave the plastic in its natural [and toughest] amorphous structure*)...
*On the equivilancy of metals and plastics in terms of structure at the molecular level:
Plastics don't generally form regular crystals like metals or ceramics; but instead form areas of crystaline microstructure inside a more confused "amorphous" structure, the formation of these crystaline areas is analogus to the formation of small discontinuites in the crystal structure of metals, and makes the plastic both harder and more brittle (also less transparent).