Choosing the Right Resin
So, you are starting a new project. You have your fabric chosen, your tools laid out and your designs are solid. But you haven’t decided on a molding resin, have you? It’s easy to overlook, when your busy comparing Kevlar to Carbon Fiber, but the resin you choose can have just as much an impact on your finished project. Molding resin selection can vary based on fabric compatibility, service conditions, and desired characteristics of the finished part.
There are generally three types of thermosetting resin to consider when approaching your project: Epoxy, Vinyl Ester, and Polyester. Here is a broad overview of what the three, including their characteristics, and what they should be used for.
For composite parts that demand the ultimate strength, fabricators will use an Epoxy Resin. In addition to increased strength properties, epoxies also generally outperform polyester and vinyl ester for dimensional stability and increased bonding with other materials.
High Strength Properties
Can be used in vacuum infusion applications
Easy to handle
Cannot be used with chopped strand mat
Not UV stable. This must be paired with a top coat when exposed to UV rays
Fibre Glast offers a host of choices when it comes to Epoxy resins. Our System 1000 Epoxy works great as a general purpose resin, while our System 2000 Epoxy, which offers the highest of strength properties which makes it great for structural aerospace. Our System 3000 and System 3300 are both high temperature epoxies, with the 3300 being perfect for exceptionally stable and long-lasting high temperature molds. For more information our our epoxies, visit the Epoxy store page.
Polyester Resins are the most widely used resins in the composites industry. Polyester Resins are less expensive, offer some corrosion resistance, and are more forgiving than epoxies. The majority of all fiberglass parts are constructed using Polyester Resins because they are easy to use, fast curing, and tolerant of temperature and catalyst extremes. Fibre Glast carries two different types of Polyester Resins, each with their own strengths and uses.
-Easy to handle
-High thixotropic index (product won’t run on vertical surfaces)
-lower physical properties compared to more expensive resins
Our #77 Polyester Molding Resin is a general purpose polyester resin, ideal as a orthophthalic fiberglass resin for part fabrication and for building low cost molds. This resin is easy to work with, less expensive compared to it’s epoxy and vinyl ester counterparts, and is wax free, meaning you won’t have to sand being coats.
-Dimensionally stable (minimal shrinkage)
-resists post cure problems
-can be used in food contact applications
-Slightly more expensive than general purpose polyester resins
The #90 Isopthalic Polyester Resin is perfect for making dimensionaly stable polyester molds, fabrication of corrosive service parts, and as a durable repair material for tank linings. The Isophtalic Resin boasts much better strength when compared to general purpose polyester resins, which allows it to be used in more demanding applications.
Vinyl Ester Resin is considered a hybrid of polyester and epoxy—meaning its handling characteristics, properties, and price generally fall just between the other two. It is important to note that, Of the three, vinyl ester resin will provide the highest corrosion resistance, temperature resistance and elongation (toughness.) Because of this, they are typically used when high durability, thermal stability, and corrosion resistance is needed.
-short shelf life (3 months)
Vinyl Ester resins are quickly becoming popular within areas of modern high performance composites. We offer the #1110 Vinyl Ester Resin, which is compatible with all of our fabrics, pigments and fillers. It is suitable for construction of most chemical storage and full tanks. Though we recommend testing the the tank for compatibility before putting it into service.
Still not sure which is right for your project? Read our full Learning Center Article About Resins. You can also reach us on our Facebook or our Twitter with any questions you might have. Let us know your thoughts in the comments below.