What is polyurethane resin and is it toxic?

• June 19 2025, by Carola Straccali
• 5 min reading time

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Wondering what polyurethane is exactly and whether it's safe to use? You're not alone. At Siliconesandmore.com, we get this question regularly—especially from makers, professionals, and hobbyists who work with casting materials. In this blog post, we'll explain what polyurethane resin is, how it's used, whether it's toxic, and how one of our customers created an impressive dragon sculpture using our flexible PU resin. Whether you're casting prototypes, models, or creative objects, understanding polyurethane will help you make the right choice for your next project.

What is polyurethane resin?  

Polyurethane resin is a two-component plastic widely used for casting, molding, coating, and sealing . It is created by mixing a polyol (component A) with an isocyanate (component B). After mixing, these components react to form a solid plastic that can be flexible or hard, depending on its composition.  

Polyurethane is popular in both industrial and creative applications because of:  

• Fast curing  

• Excellent detail reproduction  

• High strength and durability  

• Suitability for pigments and fillers  

• Possibility to pour in thick layers  

Polyurethane casting resin is particularly suitable for small to medium-sized molds, functional prototypes, and artistic creations.  

Looking for a strong, fast-curing resin? Check out our PU Casting Resin D70 – perfect for precision molds and fast processing.
Prefer flexibility? Try our Flexible Polyurethane PT 85 – ideal for flexible or impact-resistant castings.  

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Is polyurethane toxic?  

This question is often asked—and rightly so. The short answer: polyurethane is safe when used correctly.  

What you need to know:  

• Uncured polyurethane , especially the isocyanate portion, can cause skin and eye irritation, as well as breathing difficulties or allergic reactions if inhaled or in contact with the skin.  

• We strongly advise against working with liquid PU components during pregnancy or breastfeeding , due to possible risks to the (unborn) child.  

• Once cured, polyurethane is inert (chemically stable) and generally non-toxic—it no longer releases fumes and remains non-reactive. However, avoid heating, sanding, or sawing the finished product.  

• PU must not come into contact with food unless specially formulated as food safe.  

• As with all chemical products: not suitable for minors and always keep out of reach of children.  

Safety tips:  

• Always wear gloves, eye protection and work in a well-ventilated area or use a respirator.  

• Never inhale fumes and avoid dust when sanding or sawing.  

• Always consult the [safety data sheets (SDS)] of the specific product.  

• Work in a separate room, out of reach of unprotected persons. Do not use the kitchen, bedroom, or other living space.  

• Do not use baking tins or kitchen utensils that also come into contact with food.  

Since August 2023, mandatory safety training has been in effect in the EU for professionals working with PU products containing more than 0.1% diisocyanates.  

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Customer project in the spotlight: A dragon brought to life with PU resin  

One of our favorite customer projects comes from NXTLVL , a talented maker who cast a detailed dragon sculpture using materials from our webshop.

This is how they did it:  

1. The original statue was sculpted in Plasticine clay .  

1. The mold was made with our Silicone Condensation 20 , for a flexible and detailed result.  

1. A sturdy epoxy support cap provided additional support.  

1. The final statue was cast with Flexible PU PT 85 , which resulted in a robust and flexible dragon statue.  

This project demonstrates that polyurethane is not only suitable for industrial applications, but is also a powerful material for art, creativity and craftsmanship .  

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Finally: Do you have to work with polyurethane?  

If you're looking for a material that 's fast, strong, versatile, and detailed , polyurethane is an excellent choice—as long as you take the right precautions.  

Whether you're a professional, teacher, or hobbyist: Siliconesandmore.com offers the right PU product for every application. From rigid casting resins to flexible compounds—we have everything you need for your creative or technical process.  

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Ready to get started?

Discover our full range of polyurethane products and bring your project to life with high-quality materials from Siliconesandmore.com.  

Fast-curing. Detailed. Performance you can count on.
Order now at Siliconesandmore.com

Tags

Flexibele Polyurethaan PT 85 giftig polyurethaan PU Gietresin D70