---
product_id: 273889732
title: "Smooth-On Cast 305 Urethane Resin (Trial Unit)"
brand: "smooth-on"
price: "$153"
currency: NZD
in_stock: true
reviews_count: 5
category: "Smooth On"
url: https://www.desertcart.nz/products/273889732-smooth-on-cast-305-urethane-resin-trial-unit
store_origin: NZ
region: New Zealand
---

# 30 min demold time Bright white, paintable 1:1 mix ratio Smooth-On Cast 305 Urethane Resin (Trial Unit)

**Brand:** smooth-on
**Price:** $153
**Availability:** ✅ In Stock

## Summary

> ⚡ Cast smarter, not faster — master your craft with Smooth-On 305!

## Quick Answers

- **What is this?** Smooth-On Cast 305 Urethane Resin (Trial Unit) by smooth-on
- **How much does it cost?** $153 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.nz](https://www.desertcart.nz/products/273889732-smooth-on-cast-305-urethane-resin-trial-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

- • **Optimized Workflow:** 7-minute pot life gives you ample time to pour multiple casts without the rush.
- • **Effortless Mixing Mastery:** One-to-one volume ratio means no guesswork—just pure, seamless blending.
- • **Perfectly Timed Precision:** 30-minute demold time balances speed and control for flawless casts every time.
- • **Durability Meets Versatility:** Tough, moisture-resistant castings that stand up to prototyping and special effects demands.
- • **Vivid, Ready-to-Finish Surface:** Bright white finish that’s bubble-free, sandable, and primed for your creative touch.

## Overview

Smooth-On Smooth-Cast 305 is a premium urethane resin kit featuring a 30-minute demold time and 7-minute pot life, ideal for professionals needing precise control and rapid turnaround. Its ultra-low viscosity and 1:1 mix ratio ensure bubble-free, bright white castings that are durable, machinable, and paint-ready—perfect for prototypes, sculptures, and special effects.

## Description

SMOOTH-ON SMOOTH-CAST 305 - SLOWER CURE TIME Smooth Cast 305 liquid plastic is an ultra-low viscosity casting resin. Does Smooth-cast 300 cure too fast for you Problem solved. Smooth-Cast 305 cures slower than Smooth-cast 300 with a 30 minute demold time and 7 minute pot life. It yields castings that are bright white and virtually bubble free. Vacuum degassing is not necessary. Smooth-Cast offers the convenience of a one to one mix ratio (one part A to one part B by volume). Fully cured castings are tough, durable, machinable and paintable. They resist moisture and mild solvents. Applications for Smooth-Cast Liquid Plastics include reproducing small to medium size sculptures, making prototype models, and special effects props.

Review: I’ve used a lot of casting resins and urethanes and this is one of the best Smooth-On has to offer. I like it better than 300 (2 min pot life and 10 minute cure), as 305 has a manageable pot life of 8 minutes and a cure time of 30. These characteristics make it an ideal material if you need to produce several casts in a day, while providing adequate time to mix and pour into your molds. The plastic is bright white as advertised when cured and durable. I’m producing very small castings (4-6 grams of material at a time) and the 1-1 volume ratio is very easy to mix and follow.
Review: This resin worked very well for my project. The resin itself is quite sturdy after casting and was easy to measure out before casting. I highly recommend!

## Features

- SMOOTH-ON SMOOTH-CAST 305 - 2 Pint Kit
- Comes with 30 minute demold time and 7 minute pot life
- Cures Slower than Smooth-Cast 300, quick enough for rapid turnaround
- Bright White Color, can be sanded and painted

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B00ZGOSTTY |
| Item model number | Smooth-Cast 305 |
| Manufacturer | Smooth-On |
| Product Dimensions | 20.32 x 15.24 x 7.62 cm; 907.18 g |

## Product Details

- **Brand:** Smooth-On
- **Colour:** Bright White
- **Item package quantity:** 1
- **Material:** Plastic
- **Special features:** Portable

## Images

![Smooth-On Cast 305 Urethane Resin (Trial Unit) - Image 1](https://m.media-amazon.com/images/I/71OvxkSuDSL.jpg)

## Available Options

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

## Questions & Answers

**Q: I want to make a mold of my dogs paw print. Will it pour into a print in the mudd and make a mold?**
A: I would think the moisture would inhibit the curing of the resin, another way to get that imprint would be to pour plaster into the muddy pawprint and let it harden then wash off  the mud.

**Q: How is the pot life?  I dont have a pressure pot so I need a slow set resin for figure parts.  This still may not be enough time for me**
A: Smooth On has three white resins: Smooth Cast 300 is way too fast for me - 3 minutes - the stream of resin I am pouring into a 2nd or 3rd mold becomes a frozen waterfall. Smooth Cast 305 works for me: pot life of 7 minutes so I pour it (clear) into my mold and after 5 minutes it starts to turn cloudy and its cured in 30 minutes. I have never bought it but the literature says they have Smooth Cast 310 with a pot life of 15-20 minutes, cure time 3-4 hours.

**Q: How resistant to ultraviolet light is this material?**
A: Hard to say. I never really thought about that. I usually paint my casted pieces, however I have many extra's casts, that have been laying around for several years, and I do not see any discoloration or any other aging effects. I'd need more information as to what you want to cast, to know if this is the right choice for you, as there are many other casting materials, such as plasters and resins. My advice is to test it out. It's not terribly expensive. You might really like it. I love the stuff,

**Q: I’m looking for a very mailable, rubber, casting material, any suggestions?**
A: for the molds or the items cast out of a mold? with the right mold release, or a PVA liner you can cast silicone into silicone. I also like flexible urethane expanding foam rubber (most of them are self skinning). You can get it in rigid or flexible, and it expands like the cans of greatstuff insulation, but stays foamy/flexible, and it much less expensive than latex foam rubber.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Review
*by D***N on 3 February 2023*

I’ve used a lot of casting resins and urethanes and this is one of the best Smooth-On has to offer. I like it better than 300 (2 min pot life and 10 minute cure), as 305 has a manageable pot life of 8 minutes and a cure time of 30. These characteristics make it an ideal material if you need to produce several casts in a day, while providing adequate time to mix and pour into your molds. The plastic is bright white as advertised when cured and durable. I’m producing very small castings (4-6 grams of material at a time) and the 1-1 volume ratio is very easy to mix and follow.

### ⭐⭐⭐⭐⭐ Review
*by A***R on 6 January 2026*

This resin worked very well for my project. The resin itself is quite sturdy after casting and was easy to measure out before casting. I highly recommend!

### ⭐⭐⭐⭐⭐ Review
*by A***R on 12 May 2024*

It works quite well if you use both a vacuum to de-gas and pressure-pot to pressurize. I still have a few bubbles float to the top or get stuck on mold features, but otherwise this is the best option I have found available on amazon. The working time is short, I only have about 3 minutes (of the 7 minutes) to get it mixed and in the mold, but not as short as the 300 version, where I only feel like I have one minute (of the 3 minutes). I did eventually switch from this to the Task 9 version to mix it with color.

## Frequently Bought Together

- Smooth-On Smooth-Cast™ 305 Liquid Plastic Resin for Special Effects, & More, White - Pint Unit
- Mold Star 15 Slow - 1A:1B Mix by Volume Platinum Silicone Rubber - Pint Unit
- Smooth-On Universal Mold Release - 14 Fluid Ounce Aerosol Can

---

## Why Shop on Desertcart?

- 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016
- 🌍 **Shop Globally** — Access 737+ million products across 21 categories
- 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price
- 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members)
- 🔒 **Secure Payments** — Trusted payment options with buyer protection
- ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews

**Shop now:** [https://www.desertcart.nz/products/273889732-smooth-on-cast-305-urethane-resin-trial-unit](https://www.desertcart.nz/products/273889732-smooth-on-cast-305-urethane-resin-trial-unit)

---

*Product available on Desertcart New Zealand*
*Store origin: NZ*
*Last updated: 2026-02-13*