Fiberglass part making

Updated: Mar 17, 2021

In this tutorial series we will learn how to make simple fiberglass parts.


Introduction

Fiberglass is a very versatile material. Can replace steel, iron, aluminum and plastic parts in almost all applications.

It doesn't rust or rot in water.

It is much stronger and lighter than similar size steel and aluminum parts.

Can be molded to form channels as well as pipes, tubes, sheets etc.

Fiberglass parts can be made without any specific molding tools and equipments.

Fiberglass parts can be very easily made at home for any DIY projects or any small workshop.


Using this tutorial you can make larger and complex parts and molds from fiberglass.


In this tutorial we will make 2 parts one with first layer of gelcoat and one without.

The application of gelcoat will provide a good and glossy surface finish.

Without a layer of gelcoat there will be some imperfections and air bubbles on the surface of the part.


Materials required:


The mold can be made from most locally available materials like steel, aluminum, wood, MDF, plastic, mirror or glass etc.

But for best results we recommend using sheet of glass as mold surface.


 

In this tutorial we are using a sheet of glass for as a mold.

The part will have the surface finish of the mold. So incase the mold surface is glossy then the part will be glossy too.

Incase the surface finish of the mold is matt finished then the part will have similar finish as well.

Today we will make 2 sheets of fiberglass one with thickness of approximately 1mm and another with thickness of approximately 3mm.


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Each sheet will be 6in x 6in

Using this method we can make sheets of fiberglass composite from as thin as 0.5mm to 25mm thick.


 


Step I: Mold preparation

Clean the mold ie. the sheet of glass using a chemical mold cleaner or soapy water and a micro fiber cloth

Step II: Application of release agent

Once dried off using a wax applicator sponge apply it to the mold surface.

Using a clean microfiber cloth buff off the dried wax from the surface of the mold.

Repeat this step 3 more times then let it dry for atleast 30mins.

Take a small quantity of PVA release agent in a cup.

Using a brush apply a very thin 'tack coat' on the mold surface. Let it dry.

Then apply a heavier coat of PVA using a brush. Once dried apply second coat of PVA for a good release.



 

Step III:

Gelcoat application

Using a weighing scale measure the required quantity of gelcoat in a cup.

Here we are using 50g of gelcoat.

To that we are adding 1ml of cobalt accelerator and mix well using a stick.

Once mixed well add 1ml of MEKP catalyst and mix well again.

Apply it an even layer about 0.3mm thick on the surface of the mold in the required size.

Let it dry to a tack state.

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Step IV:

Fiberglass cutting

We are making 2 sheets of 3mm and 0.8mm each.

For 0.5mm we are laying 2 layers of 300gsm CSM\

And for 3mm sheet we will lay 2 layers of 300gsm CSM and 3 layers of 600gsm cloth.

Applying tape on the edge of the cloth will give a clean cut to the fabric and will be cut out once the part is fully cured.

We are cutting it a little larger than required part size.

As the final sheet size will be 6in x 6in we are cutting size of 8in x 8in



 

Step V:

Resin mixing

The amount of resin required for laminating fiberglass sheet will the approximately the double the weight of the fiberglass fabric.

Measure the fiberglass pieces cut earlier, then note it down.

The weight of the cut sheets of fiberglass is about 127g, so the will weigh out about 200g of ISO polyester resin.

In a mixing cup weigh about 200g of ISO polyester resin.

We will be using 2.5ml of cobalt accelerator, add it to the resin and mix very well.

Then measure 2.5ml of MEKP catalyst and add it to the resin again mix it very well.