Polyester Resins

Polyester resin is most commonly reinforced with glass fibre to produce a material which provides ease of handling, low cost, and dimensional stability. It also offers a great variety of finishes. It is the least expensive of the resin options.

It can be used in applications ranging from sleek automotive body panels to rugged floor or wall panels. It is particularly well suited to kitchens, bathrooms, and other areas that require washable low-maintenance walls. Its low density makes it up to five times lighter than equivalent metal parts and its strength to weight ratio is very good.

The composite’s strength can be increased or decreased by altering the proportion of reinforcement. Fillers may also be added to extend the value of the resin, reducing the cost of the final composite by as much as 50 percent.


  • Least expensive option
  • Can be tailored to meet a wide range of end-use applications


  • Only moderate mechanical properties
  • High styrene emissions in open moulds
  • High cure shrinkage Limited range of working times

Processing technologies

The best processes for producing parts with this material are:

  • Open moulding
  • Resin transfer moulding (RTM)
  • Sheet moulding compounds (SMC)

BFG International’s experienced designers and engineers select the optimal process in each case based on variables such as the client’s tooling budget, dimensional tolerance and physical properties of the parts, and production volume.

Techinical details
Maximum use temperature79 – 141 °C
Flexural strength8 – 23 ksi
Flexural modulus0.5 – 0.6 Msi
Tensile strength3 – 13 ksi
Tensile modulus0.3 – 0.6 Msi
Density1.1 – 1.2 grams/cc
Moisture absorption0.15 – 0.60 %
Elongation1.4 – 4.0 %
Coefficient of thermal expansion (x10-5)None
Contact us to discuss your project with one of our experts in the field.