3D Print Detailed, Opaque Parts with Formlabs’ New Grey Resin

One of the main advantages to stereolithography (SLA) over Fused Filament Fabrication (FFF) is the accuracy that parts can be printed to. SLA 3D printers, such as the Formlabs Form 2, can reproduce finer details than similarly priced FFF 3D printers which makes them ideal for creating true-to-design concepts. The downside to SLA is that because SLA 3D printers have to use a photocure resin, they are limited in the range of materials they support.

Material Development


The way around that limitation, as Formlabs has proven, is research and development to create new resins with different properties pre and post-cure. Formlabs now have resins for a wide range of applications, with Standard, Engineering, Jewlry and Dentistry product lines. And later this year, they will make available a new ‘Ceramic Resin’ that 3D prints with the look and feel of white ceramic, which after firing, becomes pure ceramic.

Formlabs’ most popular resins are, of course, the Standard Resins which comprise of Clear, White, Grey and Black resin. The Standard resins are designed for high-resolution, accurate prototyping and product development. Formlabs recently updated their Grey Resin to v3, which we will take a closer look at below to determine where it should be used. It’s important to note that v3 (GPGR03) is a reformulated version of the Grey Resin available through 2016 (GPGR02).

New Grey Resin – Characteristics

Formlabs Grey Resin v3 has a new matte, opaque finish. It offers the highest surface detail of any Formlabs material to date, which makes it the go-to material choice (ahead of White and Black resin) for prototyping, and for creating models that will have plenty of detail and depth.

Grey Resin

Imaged above: A model printed by Formlabs. Look closely, and you can see how light catches the model to reveal lots of detail.

Compared to the previous version, Grey Version v3 has a darker finish that’s more opaque. Light appears to just absorb into parts which appear elegant and professional. Perhaps the best characteristic of this reformulated resin, however, is that layer lines are now less visible. You can still see them, but they are less pronounced than before which reduces the need for sanding or polishing – although Formlabs do state that sanding and polishing are recommended if you plan to paint parts.

Another characteristic of Grey Resin v3 is that extremely thin and fine details will be printed in the same opaque grey as the rest of the model. Older versions of this resin would print clear on extremely fine details.

New Grey Resin – What is it for?

Grey Resin has properties engineered for fine detail and functional prototypes. When printed, Grey Resin has a tensile strength and Young’s Modulus that’s similar to ABS, so it is a resilient and strong material.

Here’s a printed model designed by George Hart:


The model pictured above was not sanded or polished. You can see that the model’s layer lines are not very prominent.

The surface finish is an opaque, matte grey, which makes printed parts and models suitable for immediate presentation or painting when post-cured. Parts are perfectly smooth and flawless fresh from the print bed, too, so without any finishing they have the look and feel of a finished product. Formlabs uses Grey Resin as a demonstration material, which is testament to its quality, and as previously mentioned, it offers the highest surface detail of any Formlabs material to date.


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