What Is Resin? A Japanese Craft Writer’s Complete Guide to Resin Types and Characteristics

Hello, this is Yassy from Crafters! (・∀・)

When it comes to overwhelmingly popular materials in the handmade world, resin is undeniably at the top of the list. Personally, I love making resin pieces, admiring gorgeous creations in shops and websites, and buying and wearing resin accessories made by my favorite craft artists! Its crystal-clear, shimmering beauty instantly captures the heart of anyone who sees it.

However, beginners who are just about to start resin crafting almost always run into the same wall: "How many types of resin are there, and what is the difference between them?"

When you browse craft supply stores or online shops, you will see a confusing array of terms like UV resin, LED resin, 2-part epoxy resin, hard type, and soft type. It is completely natural to feel overwhelmed and unsure about which one to choose for the project you want to make.

Resins differ completely depending on their type—including how they cure, which projects they suit best, and key safety/handling points. If you purchase resin liquid blindly without understanding these fundamentals, you will inevitably face frustrating mistakes like resin that won't cure, stays sticky, or warps out of shape.

In this guide, I will share all my crafting knowledge to thoroughly explain everything from basic resin knowledge to the distinct characteristics, pros and cons, and correct usage of each type! By the time you finish reading, you will clearly know which resin liquid is perfect for your upcoming project. Let's dive in and take your first step toward successful resin crafting!

What Is "Resin"? Basic Knowledge for Handmade Crafts

First, let's clarify the original meaning of the word "resin" and what material it refers to in the craft world.

The word Resin originally refers to natural resins secreted by trees, such as pine resin. However, in the world of handmade crafting, "resin" refers to liquid synthetic resins created chemically.

These liquid resins have the property of solidifying into a hard, plastic-like state when exposed to specific triggers (such as light or chemical reactions). This ability to pour liquid into any shape and solidify it is resin's greatest feature and charm.

Why Is Resin So Popular in Crafting?

There are three main reasons why resin is loved by so many crafters:

• Stunning Transparency and Gloss: You can easily achieve a high-grade transparency similar to glass or crystal.
• Incredible Inclusions: You can encapsulate almost anything—dried flowers, pressed flowers, glitter, beads, illustrated paper, and more.
• Ease of Molding: Simply pour resin into a silicone mold, and complex 3D parts are finished in a flash.

I still remember the sheer thrill when I made my very first resin project. I encapsulated dried flowers and glitter in resin, cured it under a light, and within just a few minutes, I held a professional-looking charm in my hands. While admiring and buying resin crafts is fun, creating clear, beautiful shapes with your own hands is truly a special experience.

Resin Is Divided into Two Main Groups

Resins used in crafting can be broadly divided into two main categories: 1-part resins (one-component) and 2-part resins (two-component).

1-Part Resin is ready to use straight out of the bottle. It cures in seconds to minutes when exposed to light (ultraviolet or LED light), making it quick, convenient, and beginner-friendly. "UV resin" and "LED resin" fall under this group.

2-Part Resin, on the other hand, consists of two separate liquids: a main resin and a hardener. You mix them together in a precise ratio to trigger a chemical reaction that cures the resin slowly over time. This is commonly known as "epoxy resin."

Understanding the difference between these two groups is the very first step in choosing the right resin. Now, let's explore the detailed characteristics of each specific type.

Comparison of the 3 Major Types of Resin Used in Crafting

Resins commonly used in handmade crafts can be divided into three main types based on how they cure.

Note: Classification methods can vary. In particular, UV resin and LED resin are sometimes grouped together as "light-curing resins" depending on the manufacturer or source. For clarity in handmade project planning, this article classifies them into three practical categories: UV Resin, LED Resin, and Epoxy Resin.

1. UV Resin (Ultraviolet Curing Resin)
2. LED Resin (LED Light Curing Resin)
3. Epoxy Resin (2-Part Chemical Reaction Resin)

Let's look at the mechanisms, benefits, and drawbacks of each.

1. UV Resin (Ultraviolet Curing Resin)

UV resin is a 1-part resin liquid that hardens when exposed to ultraviolet (UV) light. It has been a beloved staple in the handmade craft world for many years.

When exposed to a specialized UV light (such as 365nm wavelength) or the UV rays contained in natural sunlight, its molecules rapidly bond and cure.

Pros of UV Resin:

• Extremely easy to find, often available even at 100-yen shops in Japan or local craft stores.
• Cures in sunlight, allowing you to start crafting without buying a light fixture right away.
• Comes in various viscosities to match different project needs.

Cons of UV Resin:

• Takes longer to cure (approx. 3–5 minutes under a UV lamp, 15 minutes to several hours in sunlight).
• Higher degree of "curing shrinkage," which can cause surface wrinkles or warping when removed from molds.
• Prone to yellowing over time (after a few months to years) due to age and light exposure.

While its accessibility is fantastic, you may find it slightly lacking if you are aiming for high perfection or long-term preservation.

2. LED Resin (LED Light Curing Resin)

LED resin is a modern generation 1-part resin liquid that cures under specific LED light wavelengths (around 405nm). It is currently becoming the primary choice in the Japanese handmade accessory market.

Pros of LED Resin:

• Remarkably fast curing speed (solidifies in just 30 seconds to 1 minute under an LED light).
• Extremely low shrinkage, yielding smooth, clean shapes that match molds perfectly.
• Exceptional clarity and many high-quality formulas that resist yellowing over time.
• Leaves almost no sticky residue on the surface after curing.

Cons of LED Resin:

• Slightly more expensive than standard UV resin.
• Requires a dedicated LED light (or a dual UV-LED hybrid light).
• Cures so fast that working near sunny windows can cause it to harden while you are still working.

In terms of finished quality, work speed, and long-lasting clarity, LED resin serves as an excellent upgrade to traditional UV resin. If you want to craft high-quality accessories, LED resin is a top choice.

3. Epoxy Resin (2-Part Resin)

Epoxy resin is a 2-part system made up of a clear main resin and a hardener. You mix these two liquids together according to a precise weight ratio (for example, 2 parts resin to 1 part hardener). It requires no UV/LED light apparatus at all; instead, it hardens gradually through the heat generated by its internal chemical reaction.

Pros of Epoxy Resin:

• Ideal for making thick, large, or high-volume pieces all at once.
• Because it does not rely on light penetration, it cures completely even inside opaque molds or deep containers.
• Bubbles rise and escape easily, producing an exquisite, glass-like transparency.
• Virtually zero curing shrinkage, ensuring high dimensional accuracy.

Cons of Epoxy Resin:

• Requires 24 to 48 hours for complete curing.
• Inaccurate measurement of the resin and hardener (even by a few grams) leads to cure failure, leaving it permanently sticky.
• Mixing two liquids easily introduces micro-bubbles, requiring careful and slow stirring.

Although it takes time, epoxy resin is essential if you want to create deep 3D art, resin coasters, or large home decor items.

Comparison Table of Resin Types

Here is a concise summary comparing the three main resin types:

As this chart illustrates, there is no single "best" resin overall—the right choice depends entirely on what you intend to make!

Understanding Resin "Hardness" and "Viscosity"

Beyond resin categories (UV, LED, Epoxy), two other vital factors affect your final pieces: curing hardness and liquid viscosity (thickness).

3 Types of Cured Hardness

Resin formulas cure into different surface textures:

1. Hard Type (Standard): The most common type. Hardens like solid plastic. Used in over 90% of standard resin jewelry like earrings, keychains, and pendant tops.
2. Soft & Semi-Hard Type: Remains flexible enough after curing to be cut with scissors (similar to hard rubber or a bouncy ball). Ideal for items attached to curved surfaces (like flexible phone cases or pass cases) or pieces you need to trim later.
3. Squishy/Silicon Type: Retains a soft, pliable texture like gummy candy or silicone. Used for fake sweet desserts (jelly/fruit effects) or tactile charms.

For general crafting, starting with Hard Type is recommended. Consider soft types only when creating specialized flexible items.

How to Use Viscosities (Thin, Medium, Thick)

When buying 1-part resins (UV or LED), bottles often indicate "Low Viscosity," "Medium Viscosity," or "High Viscosity." Master these to boost your crafting efficiency:

• Low Viscosity (Watery/Runny): Flows effortlessly into fine mold details and allows bubbles to escape easily. Perfect for intricate silicone molds.
• Medium Viscosity (Standard): The most versatile thickness. Handles everything from bezel pouring to mold casting smoothly. When in doubt, start here.
• High Viscosity (Thick/Honey-like): Perfect for create a rounded, domed finish on top of charms (doming/coating) without overflowing the edges.

In my own workflow, I cast base parts inside silicone molds using low-to-medium viscosity resin, and then apply a final top coat of high viscosity resin to achieve a plump, high-end shine. This simple step elevates handmade pieces to store-bought quality!

How to Choose the Right Resin for Your Specific Project

Here is a simple decision guide based on what you want to create:

Pattern 1: Small Earrings, Keychains, and Charms

Recommended Choice: LED Resin (Hard Type, Medium Viscosity)LED resin is ideal for small accessories. It cures in seconds, speeding up your process while delivering crisp, non-warped, sparkling results.

Pattern 2: Coasters, Ocean Resin Art, Large Orgonites, or Wood/Resin Tables

Recommended Choice: Epoxy Resin (2-Part Resin)Never use 1-part UV or LED resin for items thicker than 1cm or larger than your palm. Light cannot penetrate deep layers, leaving the core uncured and sticky. Always use 2-part epoxy resin for deep casts.

Pattern 3: Spherical 3D Charms with Dried Flowers

Recommended Choice: Low-Viscosity LED Resin (Layered) or Epoxy ResinHigh viscosity resin traps air between delicate flower petals, creating large bubbles inside 3D sphere molds. Use low-viscosity LED resin poured in thin layers and cured step-by-step, or use epoxy resin to allow natural bubble release.

3 Common Resin Pitfalls and How to Avoid Them

Here are three frequent mistakes beginners make, along with the chemical reasons and solutions to prevent them!

Pitfall 1: "My LED resin won't cure under my UV lamp!"

Many beginners assume any resin lamp works for all resins, but resin cures only when exposed to specific light wavelengths (measured in nanometers, nm):

• Traditional UV Resin: Cures around 365nm wavelength.
• Modern LED Resin: Cures around 405nm wavelength.

If you put LED resin under an older UV-only lamp (the large tube type), the wavelength match fails, leaving the resin liquid or tacky. When buying a lamp today, always choose a Dual UV-LED Hybrid Lamp (365nm + 405nm compatible) so you can cure both resin types flawlessly.

Pitfall 2: "I poured a thick layer and it stayed uncured inside!"

1-part light-curing resins harden from the top down where light hits. If you pour a deep mold full at once, light cannot reach the bottom. The top cures while the center remains wet.

The Golden Rule: Work in thin layers (2mm to 3mm at a time) and cure each layer with your lamp before adding the next. This layering technique guarantees full curing throughout the piece.

Pitfall 3: "My clear piece turned yellow after a few months!"

Yellowing occurs when resin degrades from exposure to solar UV rays and oxygen over time. Lower-quality resins or older UV formulas can turn yellow quickly.

The Solution: Use high-quality LED or epoxy resin specifically labeled as "UV-resistant" or "Non-yellowing." Save budget/100-yen resins for rough practice, and invest in reputable craft brands for finished pieces intended for gifts or sales.

4 Quality Checklist Points for Buying Resin Liquid

Extremely cheap bulk resin liquids online can be tempting, but poor-quality resin causes frustration, noxious fumes, and failed projects. In the past, I bought a cheap unknown resin online that filled my room with harsh fumes and left a greasy texture even after curing—I had to throw it away!

Check these four criteria when selecting resin:

1. Post-Cure Clarity: High-quality resin cures crystal clear without cloudiness.
2. Low Odor: Reliable Japanese craft manufacturers formulate resins with reduced chemical odor for a comfortable workspace.
3. Curing Surface Finish: Good resin cures rock-hard and smooth without tacky finger marks.
4. Ease of Bubble Release: Quality resins have surface tension tuned to allow air bubbles to rise and pop naturally with gentle heat.

Resin is the literal foundation of your artwork. Choosing trusted specialized brands (such as Padico or Kiyohara in Japan) is the best secret to smooth crafting success.

Essential Safety and Technique Rules

Safety First: Allergy Prevention & Ventilation

Direct skin contact with liquid resin carries a risk of developing resin allergy (contact dermatitis). Once developed, it can prevent you from crafting with resin in the future.

• Always wear disposable nitrile or vinyl gloves; never touch liquid resin bare-handed.
• Open at least two windows and turn on exhaust fans to maintain constant airflow.
• If resin touches your skin, wash thoroughly with soap and water immediately (wiping with alcohol sheets alone is insufficient).

Pro Technique: How to Eliminate Air Bubbles Completely

Bubbles spoil crystal clarity. Follow these steps for professional results:

1. After mixing colors or glitter, let the resin sit untouched for 3 to 5 minutes so bubbles naturally float to the surface.
2. Pop surface bubbles with a toothpick or scoop them to the edges.
3. Pass an emboss heater (heat tool) briefly over the surface to warm the resin, lowering its viscosity and popping micro-bubbles instantly.

Conclusion: Master Resin Types for Your Best Creations!

We've covered the fundamentals of craft resin, the three major resin types (UV, LED, Epoxy), their characteristics, and crucial safety and technical tips!

Quick Recap:

• Small Accessories: Use fast, clear LED Resin.
• Thick Items & Coasters: Use 2-part Epoxy Resin.
• Lamp Selection: Pick a dual-wave UV-LED Hybrid Lamp.
• Quality Key: Layer thinly, cure incrementally, and take time to pop bubbles.
• Safety Standard: Wear gloves and maintain good room ventilation.

Once you understand how resin behaves, it is an accessible and joyful craft material. Transforming your creative ideas into clear, radiant 3D art is an exhilarating feeling!

I hope you enjoy exploring resin crafting and creating stunning pieces that bring you joy to make, wear, or share. Until next time, happy crafting from Yassy!

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