This is a guest post in collaboration with Sunlu Resin

3D printing has revolutionized manufacturing and design by allowing for the creation of complex objects through an additive process. One of the most popular methods of 3D printing is stereolithography (SLA), which uses a liquid resin that is cured layer-by-layer to build an object. But what exactly is the 3D printer resin made of?

Composition of 3D Printer Resin

The resin used in SLA 3D printing is a photopolymer resin. It is composed of monomers and oligomers that crosslink together when exposed to light to form solid polymers. The main ingredient is usually an acrylate monomer such as methyl methacrylate. This gives the resin the ability to harden when light shines on it.

SLA resins also contain photoinitiators – these are compounds that initiate the polymerization reaction when exposed to light. Common photoinitiators include benzophenone and triaryl sulfonium salts. Without photoinitiators, the resin would not be able to solidify upon light exposure.

In addition, SLA resins have dyes, pigments, and fillers added to control their optical properties. For example, darker colors will absorb light faster than lighter colors. Fillers like silica can modify the physical characteristics of the cured resin.

The composition of the resin can be customized depending on the needs of the application. For instance, resins can be formulated to be flexible, heat resistant, castable, or biocompatible. The viscosity and curing properties can also be adjusted as needed.

In summary, SLA 3D printing relies on photopolymer resins composed primarily of acrylate monomers and oligomers. Upon exposure to light, photoinitiators trigger polymerization to transform the liquid resin into hard plastic. The precise formulation allows for control over the final material properties. As 3D printing advances, resin technology will continue evolving to enable new applications.

Types of 3D Printer resin

There are many different 3D printer resins available today with varying properties, thanks to years of development. Especially in industrial resin 3D printing, manufacturers have created specialized resins for different applications. For example, Formlabs developed silicone resin, alumina resin, ceramics resin, and resins for jewelry, etc. Consumer resin 3D printer companies also offer options like rigid resin, rigid plus resin, water washable resin, tough resin, high-temp resin, ABS-like resin, PA-like resin, and ABS-like water washable resins. Let’s take a closer look at some of these.

Rigid resin

Rigid resin, also called standard resin, is the most commonly used. It can produce high precision models, but the prints are very brittle. So it’s not suitable for figures or props that need durability.

Rigid plus resin

Rigid plus resin is a modified rigid resin that reduces brittleness. Different brands have their own formulations, but these resins improve toughness to make prints less prone to breaking.

High tough resin

High tough resin is similar to rigid plus, but improves toughness even more. Prints won’t break easily if dropped. This makes it great for printing figures.

Water washable resin

Water washable resins don’t require alcohol for washing off excess resin after printing. It can clear up by water. This makes cleanup much easier on your hands and avoid direct contact of your hands with alcohol.

ABS-like resin

ABS-like resin has properties similar to ABS plastic as the name suggests. It offers high strength, impact resistance, and hardness. This makes it good for functional parts and industrial applications.


In summary, resin 3D printing can achieve more detail than FDM, but the materials are more expensive. The process is more complex with post-curing and washing required. While consumer resins currently have fewer options than FDM filaments, more specialty resins will likely emerge as costs decrease.

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