Louis, I have considered the problem of bonding the plastic skin to the core but I think that once the hot plastic is vacuum formed…and then it cools… and shrinks… I think it will grab onto the blank in a highly intimate manner that wont require any adhesive.
Considering that the thin plastic will be sucked onto the blank and then when it cools it will shrink even further, Im thinking that even with a shrinkage of 2% as it cools, its not going to need any glue. The blank might even be in peril of being crushed as the shell contracts !
I reckon its one of those things that could be pondered for ages but a few experiments will show whats needed.
For the guys new to vacforming, its simple.
![](http://i153.photobucket.com/albums/s225/SURFFOILS/The%20V2/VF1.jpg)
Theres 2 processes involved…
Heating then Vaccing
Or softening the plastic and then sucking in onto a mold.
Or Thermo and then Forming… hence thermo-forming.
Heres a small setup but totally capable of being replicated to do surfboards.
![](http://i153.photobucket.com/albums/s225/SURFFOILS/The%20V2/VF1.jpg)
The plastic sheet is held flat in a rigid frame. The plastic sheet is usually about .5 mm thick, or about .02 of an inch, so its very light and thin.
Its held over a heating element / table on the right until the plastic softens.
The frame and the plastic is then flipped over onto a vacuum table on the left, where the mold is waiting. For a surfboard the ‘flipping’ would be done along the longitudinal sides.
The plastic sheet covers the mold and is sucked down over the mold by the vacuum pressure from below.
Due to the heat and the vacuum, the plastic skin forms to the shape of the mold and when it cools it retains the shape of the mold.
I did a bit of this thermo forming about 4 years ago but not of the scale of a complete surfboard.
Ive got the oven setup to do the test samples but I need to build a vac table or similar.