---
product_id: 458820556
title: "Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit)"
brand: "smooth-on"
price: "€ 398.20"
currency: EUR
in_stock: true
url: https://www.desertcart.fi/products/458820556-smooth-cast-onyx-fast-ultra-black-urethane-resin-gallon-unit
store_origin: FI
region: Finland
---

# Cost-effective solution High heat resistance Ultra-black finish Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit)

**Brand:** smooth-on
**Price:** € 398.20
**Availability:** ✅ In Stock

## Summary

> 🖤 Unleash the Power of Black with Smooth-Cast Onyx!

## Quick Answers

- **What is this?** Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit) by smooth-on
- **How much does it cost?** € 398.20 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.fi](https://www.desertcart.fi/products/458820556-smooth-cast-onyx-fast-ultra-black-urethane-resin-gallon-unit)

## Best For

- smooth-on enthusiasts

## Why This Product

- Trusted smooth-on brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Heat Warrior:** Superior heat resistance compared to other black resins.
- • **Safety First:** Crafted without mercury, ensuring a safer workspace.
- • **Budget-Friendly:** Get premium quality without breaking the bank.
- • **Effortless Elegance:** Achieve a stunning black finish without the need for color pigments.
- • **Polish to Perfection:** Easily buff to a high gloss shine for that professional touch.

## Overview

Smooth-Cast Onyx Fast is a premium ultra-black urethane resin that offers a mercury-free formulation, exceptional heat resistance, and a cost-effective alternative to traditional black resins. With a Shore hardness of 80D, it allows for easy polishing to achieve a high gloss finish, making it the ideal choice for professional projects.

## Description

Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit)

## Features

- Convenient if you desire a black casting, adding color pigment is not necessary (can be polished and buffed to a high gloss shine)
- Unlike other black resins, ONYX does not contain mercury
- ONYX offers higher heat resistance vs. competitive black resins
- ONYX is less expensive vs. other black resins
- Shore 80D

## Images

![Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit) - Image 1](https://m.media-amazon.com/images/I/41jWWhVGtGL.jpg)

## Available Options

This product comes in different **Size** options.

## Questions & Answers

**Q: Is this product and the 80D hardness suitable for casting automotive / tractor steering suspension bushings?**
A: for suspension bushings, I think you would be looking at something much more like a 60-80 Shore A, instead of 80 Shore D. Here's a chart: https://goo.gl/images/Yo0hnp

**Q: how much is there?**
A: 1 lb each

**Q: Can this be used to make  longboard wheels?**
A: If a proper mold is used, this material will harden into any desired shape. Although the shrinkage is minimal, I would suspect shrinkage should be taken into account when molding something as precise as a wheel. Whether the material holds up to the rigors of longboarding is questionable. The material is quite hard when fully cured. I haven't looked at the spec sheet in quite some time, but the cured product definitely feels harder than skateboarding wheels, and considerably more brittle. I would suspect the finished wheel would slide quite a bit. Hope this helps.

**Q: Is the final mold heavy? (Ex: mold size 11x6x2)**
A: If the final casting is 132 cubic inches - as you indicate - the piece would weigh 4.76 pounds

## Frequently Bought Together

- Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit)
- Smooth-Cast 300 - Bright White, Ultra Low Viscosity Liquid Plastic - Gallon Unit
- Rebound 25 - Brushable Platinum Silicone Rubber - Gallon Unit

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**Shop now:** [https://www.desertcart.fi/products/458820556-smooth-cast-onyx-fast-ultra-black-urethane-resin-gallon-unit](https://www.desertcart.fi/products/458820556-smooth-cast-onyx-fast-ultra-black-urethane-resin-gallon-unit)

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*Product available on Desertcart Finland*
*Store origin: FI*
*Last updated: 2026-02-02*