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FIBREGLASSING TUTORIAL

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It may not be published nor reproduced in any other form.

Fibreglassing of foam models sounds difficult, many people would be thinking resin, hardeners, mess and toxic materials! It couldn’t be further from the truth though, adding glass cloth to your foam model is actually very easy and safe, the materials we use are easily purchased at local hardware outlets and it all cleans up with water!

First you need to buy some glass cloth. We use 25 gram cloth, or more commonly known as ¾ ounce. This is a very light finishing cloth with a fine weave, it adds no real weight to your model, especially the amount you actually end up using.

The coating used to adhere the glass is where the majority of weight comes from. In this case we use a water based Polyurethane, you can buy it from bunnings and it’s called Cabbots Crystal Clear. Buy the satin finish version.

I will give examples for glassing using our popular F16 jet as a basis. Above is a picture of the lower ducting, it is a semi circular foam molding that is in contact with the ground on every landing. It is highly advisable to strengthen this area in order to increase the models resilience to landings.

I always glass the pieces of a model before assembly if possible. Unless it is a wing that needs assembly before it is covered, I will try to do the two halves separately as it is easier to manage smaller sections.

First thing is to sand the foam you are about to glass, use 400 grit aluminum oxide paper, the white one you can find in most hardware shops. Lightly sand the surface being careful not to catch the edge of the paper as it will tear lumps from the foam. Any holes or marks can be filled with RED DEVIL spak filla.

Once sanded blow as much foam dust off as you can, compressed air is the best thing, then clean with alchohol, or even a damp cloth will suffice.

Cut your glass slightly oversize to the piece being worked on, lay it over the part and then start from the middle and brush the Polyurethane into the glass, working out towards all the edges. Basically you are painting the foam! Use a liberal amount of Polyurethane, if you try to get away with too little the glass will lift in areas and can be peeled off easily. It is better to use more than is necessary and then sand the surface back after it is dry.

As you come to edges use a pair of sharp scissors and trim the glass, doing this as you work the PU into the glass makes it easier to get a nice finish, once trimmed, brush lightly over the edges to make sure they are sealed down. Once dry you will be able to further trim them, and then sand them smooth. The glass and PU sands very easily.

The glass will follow reasonably complex shapes, I can glass the upper fuselage of the F16 in one piece with no wrinkles or gaps, just take your time and work the glass around corners, keep it wet and well stuck down. You can use your fingers to work with the glass, as the PU is water based there are no problems with cleanup after you have finished.

Once you have glassed the part, trim all the holes and edges then sand smooth, once this is done you can put another coat or three of PU over the part to fully seal it, then final light sand once this is dry and you are ready to assemble the model!

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