Aviater,

The second set of photos you just posted would indicate the temperate is about right as the tiny "whiskers" are clearly visible. There will usually be some small imperfections that need to be easily sanded out to a smooth surface. I suggest making sure the edges of the templates are absolutely smooth to keep the hot wire from snagging (however briefly), as this will also cause unwanted grooves in the foam core. Do not press the hot wire against the template while cutting the core because this causes friction that can snag the hot wire. Instead just keep the hot wire barely touching the template using the least possible pressure needed to maintain contact.

Know that when you make a longer cutting bow, the voltage needed to maintain the right amperage across the longer wire will increase and you will have to adjust the temperature again. This is why I recommend using a light dimmer switch in the circuit to allow adjustment.

There are several options available when it comes time to skin the core. Southern's Sorghum water based contact adhesive by Dave Brown Products has been considered the bench mark for gluing on wing skins, but has been discontinued. I found this close alternative at https://aerocompositesrc.com/product...-s-sorghum-ii/ Another alternative is 3M's formula M77 or M88 spray can contact adhesive which also works well. Make sure the glue you use is compatible with the foam core. Spray the core and the skin and let them air dry to the touch. Then lay the wing core back in the block of foam from which it was cut and set it on a flat surface. This will keep the core from warping while applying the pressure needed to attach the skin. Make sure the core and skin are aligned exactly before letting them touch because the bond will be instant when they touch and no further adjustment will be possible. There are a variety of skin materials available ranging from 1/16" balsa to 1/64" plywood to my favorite which is plain old poster paper (cheap-cheap-cheap) from Dollar Tree or Walmart. The poster paper has a "grain" to it that will allow it to be bent around a leading edge, but only if the "grain" is running parallel to the leading edge. You can bend the poster paper some and immediately know which way the "grain" runs, It will bend easily in one direction, but buckle and crease if bent in the other direction. Using this technique, I can usually start at the trailing edge and apply the skin forward to and around the leading edge and then continue back to the trailing edge to cover the wing top and bottom in one piece. You will know why I use poster paper once you calculate the cost of balsa or the very expensive 1/64" plywood. The poster paper is only slightly heavier, is still plenty strong and can be spray painted or covered with Ultracote.