Flyfast,
Are trying to join two pieces of covering there, or is it layer of yellow with the blue over the top of it?? It looks like two pieces joined where they meet. If this is true then you need to assemble your pieces prior to putting them on the plane. Get a piece of glass or a mirror. Align your pieces together and overlap the edges by approximately 1/4" and use a trim iron (or the tip of your covering iron) to heat the area where the two pieces meet to attach them to each other. Now peel the assembled piece off of the glass and place it on your part to be covered and apply the covering as you normally would. This should stop the pieces from puckering like they are in the picture. Also, it will allow you to get the covering tighter as the assembled pieces will not act as one piece.</p>

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Ken</p>