How do epoxy and fiberglass differ

Epoxy resin or polyester resin - which is better?

Polyester resin the cheap alternative?

The addition of hardener is variable to a certain extent when mixing polyester resin. Therefore, mixing is not quite as time-consuming and difficult as with epoxy resin. Nevertheless, the amount of hardener that is added to the polyester mass should be between 1.5 and a maximum of 2.5 percent.

Strength and fiberglass mats

However, if you add too much hardener to the polyester resin so that it becomes just as strong as the epoxy resin, it becomes brittle and more fragile. If too little hardener is added, complete hardening often cannot take place. However, polyester resin bonds better to fiberglass mats than epoxy resin. The binder in the fiberglass mats is dissolved by the styrene it contains.

Disadvantages of polyester resin compared to epoxy resin

The disadvantages of one product are of course always the advantages of the other.

  • strong unpleasant odor when drying
  • lower strength
  • often not completely hardened
  • Not suitable for indoor use
  • less stable in water
  • can emit pollutants even after drying

Epoxy resin - the expensive all-rounder

For many applications, epoxy is much more suitable than polyester resin, but it is also a lot more expensive. The odor development is very low and after curing, epoxy is absolutely impact-resistant, if it has been mixed correctly. In addition, epoxy resin bonds better to a wide variety of materials, even if they are perfectly smooth. With metal or glass, only epoxy can actually be used.

Disadvantages of epoxy resin

  • significantly more expensive
  • Mixing ratio must be adhered to exactly
  • Glass fiber mats that contain styrene are difficult to process
If you need one of these products for your home, in the vast majority of cases epoxy resin is the better choice, despite the higher price. In any case, only epoxy works for structures in the aquarium or terrarium, as the polyester resin could kill the animals through its vapors.