How does mold making with epoxy resin work?

In contrast to mold construction with polyester resin, mold construction with epoxy resin offers the advantage of low shrinkage, greater strength and problem-free, low-odour processing.

The mold construction with epoxy resin can usually be done according to the following pattern:

Breaking the shape:

The first step is to separate the shape. This can be done in different ways. Here the background is important. Separating paste should be applied to porous substrates. This is applied and lightly polished out again in quick succession. For nine forms, the application should be repeated several times.

The liquid release wax should be used for smooth moulds. The release wax (liquid) is applied to the mold using a soft cloth. After flashing off, a matt surface is created. After airing, the surface should be lightly polished with a soft cloth. For nine forms, this procedure should be repeated 3-4 times. After separating with release wax, additional PVA release varnish can be applied. The PVA release varnish is applied using a foam brush or a soft foam. After a few minutes, a foil-like surface develops. This may no longer be polished. PVA release lacquer is only applied once. If residues of PVA-Trennack remain on the mold after demoulding, this can be washed off with warm water.

After cutting the mold, the epoxy mold making gelcoat is applied. Ideally, apply twice in a criss-cross pattern. To do this, the epoxy mold making gelcoat is homogeneously mixed with the hardener. After mixing, the epoxy mold making gelcoat is applied to the mold with a brush. After the first layer has gelled, the second layer can be applied. The second layer can then be applied when the first layer has hardened but is still tacky.

After the mold construction gelcoat has hardened, lamination can begin. Various types of layer construction can be selected for the shape. A possible layer structure is a sandwich of glass filament fabric / glass fiber fabric / glass filament fabric. This layer structure ensures very high strength at a low weight. When building up layers, the glass filament fabric is laminated on first. Ideally, the next layer should be laminated wet-on-wet. It should be noted that each layer is deaerated. This can be done with a ventilation roller, for example. If the layers cannot be built up wet-on-wet, the last layer must be sanded before a new layer is applied.