I have a guitar and also the rectangular cardboard box which it was delivered in. I want to make a more durable carry case for the guitar using the cardboard delivery box. It seems a shame to throw away a perfectly good box which is already the correct size and I don't want to buy a guitar case just yet. Dimensions of the box are 100x45x17 centimeters. The cardboard is made from two layers of corrugated material sandwiched in three layers of flat. I find from research that the cardboard needs to be sealed first with pva/wood glue after which fine woven glass cloth and then polyester resin can be applied. In previous experiments (when I didn't understand the necessity to seal it first) the cardboard warped and destroyed the shape of my project which was a tea tray. My question is how can I stop the cardboard from warping? If successful with the glassfibre I then want to apply a final color coat( I think this is called a gel coat).
1 Answers
Consider that the typical multi-layer corrugated cardboard material has all the flutes running parallel/in the same direction. In order to minimize the warping you are experiencing, it would be necessary to create additional layers by using adhesive to bond "cross-grain" cardboard to the existing surface. You'd have to pick an adhesive, perhaps via experimentation that would not create warping while being applied or while curing.
PVA/wood glue is water based and will indeed warp while creating the new layers. Contact cement is not water based (unless you buy that particular product!) and will provide strong bonds between layers.
Additionally, gel coat is usually applied as the first layer within a mold, excluding ambient atmosphere during the curing process. Be sure to select a gel coat product which provides for this aspect of your build. For outer skin application, the terms "gel coat with wax" will provide suitable results in a search. Useful information at the linked site.
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