---
title: "NIST developing viscosity metrology standard for ceramic AM"
url: https://www.voxelmatters.com/nist-developing-viscosity-metrology-standard-ceramic-am/
date: 2026-08-04
modified: 2026-08-04
lang: en
author: "Tess Boissonneault"
description: "When Sir Isaac Newton came up with his law of viscosity—which states that a liquid's thickness remains consistent even when subjected to movement or force—he was not talking about ketchup...."
categories:
  - "AM Research"
  - "Ceramic Additive Manufacturing"
  - "Standards"
tags:
  - "insights"
image: https://www.voxelmatters.com/wp-content/uploads/2026/08/ceramics-research-1-640x425.jpg
word_count: 644
---

# NIST developing viscosity metrology standard for ceramic AM

When Sir Isaac Newton came up with his law of viscosity—which states that a liquid's thickness remains consistent even when subjected to movement or force—he was not talking about ketchup. This condiment, as anyone who has used a glass ketchup bottle will know, has a variable viscosity, effectively becoming less viscous when a force (i.e. bottom of the bottle tap) is applied. Why does that matter for ceramic 3D printing? Because ceramic slurries are also non-Newtonian fluids with changing viscosities, a fact that introduces certain challenges for [ceramic AM](https://www.voxelmatters.com/category/additive-manufacturing/ceramics/) users, particularly when it comes to consistency and establishing standards.

To address these challenges, a team of researchers from the U.S.' National Institute of Standards and Technology (NIST) is working towards establishing standardized measurement procedures for characterizing ceramic AM feedstocks. This work is focused on measuring the viscosity of ceramic slurries used in direct ink writing (DIW) and vat photopolymerization (SLA, DLP), which are UV curable resins loaded with technical ceramic particles.

"Understanding how the slurry flows is key to getting a good final result for both of these methods,” explained NIST materials scientist Russell Maier. “Sometimes you want the slurry to flow easily, and other times you want it to keep its shape."

[![NIST developing viscosity metrology standard for ceramic AM](https://www.voxelmatters.com/wp-content/uploads/2026/08/rheology-1-340x189.jpg)](https://www.voxelmatters.com/wp-content/uploads/2026/08/rheology-1.jpg)At the core of the research is the development of a ceramic AM reference material, a sample that comes with detailed documentation and is used to calibrate equipment and test measurement methods. The NIST researchers have created a reference material consisting of zirconia particles suspended in a liquid polymer matrix. Instead of using water in the slurry, the team has opted to use polyethylene glycol, a synthetic polyether compound with many applications in healthcare and cosmetics (such as lip balm), which won't evaporate and dry out the slurry sample.

The ceramic slurry sample is notable for its ability to deliver consistent measurements using a rheometer, a viscosity measurement tool. This tool works by placing a small sample of a material between two plates, these two plates then gently compress the sample and one plate rotates to measure how much force is required to make the material flow. In ceramic AM, rheometers are used to check the quality of raw materials and characterize their bahaviors before printing. However, it is often difficult to get a precise, reliable measurement with 3D printing ceramic slurries due to the changing nature of the material, and the slipperiness of some slurries, which can affect readings.

Not only does the reference material developed by NIST use a non-evaporating liquid, it also comes with instructions on how to "reset" its viscosity: it can be twisted rapidly to decrease its thickness and then left to relax completely, which will get it back to its most viscous state and mean it's ready to measure. Having the reference material will enable ceramic AM scientists to compare their own rheometer results the NIST standard for greater material consistency.

In the next stage of the research, Maier and his team will be sending samples of the reference ceramic slurry to research labs all over the country—specifically to 20 laboratories including in industry, academia, and national laboratories—which will conduct their own viscosity tests and compare their results. If the results are consistent across the board, the work will progress towards establishing the zirconia material as a standardized reference material.

As NIST writes of the ongoing work, "A multi-laboratory interlaboratory study on rheological measurements of concentrated ceramic suspensions for DIW... is generating reference datasets and identifying sources of measurement variability to support consensus test methods through ASTM F42 and ISO TC 261."

The feedstock characterization project is just one of many [research initiatives at NIST](https://www.nist.gov/programs-projects/additive-manufacturing-ceramics) centered on ceramic additive manufacturing. Researchers there are also working on advancing the standardization of defect metrology for 3D printed ceramic parts; developing in-situ synchrotron X-ray characterization techniques for ceramic AM and sintering; and exploring the optimization of cold sintering.