90 - Isophthalic Polyester Resin
Details
Details
Build Strength and Stability for Tough Parts
90 Isophthalic Polyester is perfect for fabricating dimensionally stable polyester molds and corrosive service parts. It is often used as a durable repair material for tank linings. This Iso polyester resin offers fast wet-out in spray-up or hand laminates. When spraying, we recommend using a 1⁄8" nozzle. The 225 degree F service temperature resists exotherm and post cure problems. 90 Isophthalic Polyester Resin has better strength properties than a general purpose polyester resin, which allow it to be used in more demanding applications.
What Is #90 Isophthalic Polyester Resin?
#90 Isophthalic Polyester Resin is a thermosetting polyester resin made with isophthalic acid, which gives it better strength properties than a general purpose polyester.
#90 Isophthalic Polyester Resin is built to fabricate dimensionally stable polyester molds and corrosive service parts, and is often used as a durable repair material for tank linings. It offers fast wet-out in spray-up or hand laminates.
Why Choose #90 Isophthalic Polyester Resin?
Isophthalic chemistry brings higher tensile strength, impact resistance, and dimensional stability to #90 Isophthalic Polyester Resin, along with good resistance to chemicals, moisture, and UV degradation. These properties let it be used in more demanding applications than a general purpose resin. Its 225°F service temperature resists exotherm and post-cure problems on demanding parts.
Because its chemical components are listed under FDA 177.2420 Title 21, properly fabricated parts may be used in food contact, electrical, and military applications.
What Are the Best Applications for #90 Isophthalic Polyester Resin?
#90 Isophthalic Polyester Resin is well suited to dimensionally stable polyester molds, corrosive service parts, tank lining repairs, and any part needing higher strength, chemical resistance, or elevated service temperature than a general purpose resin provides.
Properly fabricated parts are suitable for food contact, electrical, and military uses.
How Should #90 Isophthalic Polyester Resin Be Used for Best Results?
#90 Isophthalic Polyester Resin is catalyzed at 1.25% MEKP and applied by hand lay-up or spray-up. The resin wets out quickly. When spraying, use a 1/8 inch nozzle. The 225°F service temperature gives margin against exotherm and post-cure issues on demanding parts.
Technical Specifications
• Type: Isophthalic polyester resin, thermosetting
• Catalyzation: 1.25% MEKP
• Service temperature: 225°F
• Spray nozzle: 1/8"
• Compliance: Components listed under FDA 177.2420 Title 21 for food contact when properly fabricated
Available Sizes and SKUs
• #90-F — Quart
• #90-A — Gallon
• #90-B — 5-gallon pail
• #90-DRUM — Drum
• #90/69-F — Quart with hardener (1 qt resin, 1 x #69)
• #90/69-A — Gallon with hardener (1 gal resin, 2 x #69)
• #90/69-AK — Case with hardener (4 gal resin, 8 x #69)
Quantity discounts available on the 5-gallon pail when 4 or more are ordered.
- Composition: Isophthalic Polyester resin is a combination of polyester resin and isophthalic acid. It is a thermosetting resin, which means it undergoes a chemical reaction when mixed with a catalyst and hardens or cures to a solid state.
- Properties: Isophthalic Polyester resin exhibits excellent mechanical properties, including high tensile strength, impact resistance, and dimensional stability. It also has good resistance to chemicals, moisture, and UV degradation, making it suitable for various applications. The chemical components are listed under FDA 177.2420 Title 21 making it usable in food and beverage contact applications.
- Application: Isophthalic Polyester is commonly used for applications that require superior strength, durability, and resistance to environmental conditions.
- Corrosion Resistance: Isophthalic Polyester resin offers enhanced corrosion resistance compared to standard orthophthalic polyester resin. It is often chosen for applications where the composite part will be exposed to corrosive environments, such as marine, chemical processing, and infrastructure industries.
- Versatility: Isophthalic Polyester resin can be used in various manufacturing processes, including hand lay-up, spray-up, filament winding, and infusion. It can be applied to create a range of composite products, such as tanks, pipes, boat hulls, automotive parts, and architectural components.
- Compatibility: Isophthalic Polyester resin is compatible with different reinforcement materials, such as fiberglass, carbon fiber, and aramid fibers like Kevlar. It can be used with various types of reinforcements to create composites with specific mechanical properties and performance characteristics.
- Curing: Isophthalic Polyester resin requires a catalyst or hardener to initiate the curing process. It will also need an air inhibitor like styrene wax or Duratec High gloss additive if used outside of a mold.
Here are some more details about Isophthalic Polyester resin:
- Improved Water Resistance: Isophthalic Polyester resin exhibits enhanced water resistance compared to orthophthalic polyester resin. This makes it suitable for applications where the composite part will be exposed to moisture, such as in marine environments or water storage tanks.
- Chemical Resistance: Isophthalic Polyester resin has good resistance to a wide range of chemicals, including acids, alkalis, and solvents. It is often selected for applications that require resistance to chemical corrosion or exposure to aggressive substances.
- Heat Resistance: Isophthalic Polyester resin has moderate heat resistance.
- Low Shrinkage: Isophthalic Polyester resin typically exhibits low shrinkage during the curing process. This can help minimize the development of internal stresses in the composite, resulting in improved dimensional stability and reduced likelihood of cracking or warping.
- Gel Time: The gel time of Isophthalic Polyester resin refers to the time it takes for the resin to reach a gel-like consistency after the catalyst is added. The gel time can vary depending on the specific resin formulation and ambient conditions. It is an important consideration for process control and workability during composite fabrication.
- UV Stability: Isophthalic Polyester resin has moderate resistance to UV degradation. However, prolonged exposure to direct sunlight may lead to color fading and surface degradation over time. To enhance UV resistance, the use of UV-resistant coatings or topcoats is recommended for composite parts exposed to outdoor or UV-rich environments.
- Styrene Emission: Isophthalic Polyester resin, like other polyester resins, contains styrene, which is a volatile organic compound (VOC) with a distinct odor. Proper ventilation and personal protective equipment (PPE) should be used when working with Isophthalic Polyester resin to minimize styrene exposure and ensure a safe working environment.
- Storage and Shelf Life: Isophthalic Polyester resin should be stored in a cool and dry place, away from direct sunlight and heat sources. It typically has a limited shelf life and may undergo changes in viscosity or other properties over time.
As with any composite material, it is crucial to follow the guidelines, safety precautions, and processing recommendations specific to the Isophthalic Polyester resin being used. This ensures optimal performance, proper handling, and desired results in the final composite product.
Every product Fibre Glast sells is First Quality Guaranteed, so you can build strong, stable parts with confidence.
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WARNING: This product can expose you to chemicals including Styrene which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov

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I was pleased to return to my favorite composite website and order my preferred resin for use in building giant scale model RC aircraft. You used to have a name for glass cloth compatible with epoxy and/or polyester resins. What happened to this important distinction?
Your service is great, your product (isophthalic resin) was exactly what I needed and it came quickly. Your online purchasing was difficult, however. It is apparently not possible to purchase something and have it sent to an address other than the billing address - at least I couldn't figure out how to do it. I had to have the resin shipped to the account because her name was on the credit card - a minor but unnecessary inconvenience. The second time I tried to order from you, I couldn't figure out why your site wouldn't let me complete my order. Fortunately, your sales person was pleasant and efficient.
I bought the quart size for a small project. I like that the container is suited for pouring; other products I've used came in quart paint-style containers with a lip that makes it messy to pour, or dip. Instructions on the can include the amount of catalyst needed for 1 ounce of resin, which is what I sometimes need for small projects. Set time was as expected for the temperature.
This was one of my smallest orders, using this to repair CenTek exhaust collector on a customers boat. Have used over 30 gallons of FibreGlast supplied resins in the past, always impressed by the high quality, ease of wet out and the tech support. Always feel bad for the people I see in the marine chain store,purchasing that jelly like, almost unusable stuff off the shelf.
This product works great, as advertised. I used this resin for building my canoe mold. Can be used in cooler temps, highly recommended.