A quarter of the world’s glass polishing powder
Electronics is a major outlet for rare-earth polishing. A peer-reviewed review published in 2018 lists the uses of ceria-based polishing powder as “glass, precision glass lenses, glass display panels, liquid crystal displays, glass magnetic memory disks, silicon wafers”, and estimates that about 75 % of glass polishing powder is consumed in traditional glass applications (including display panels, flat glass and optical glass) and around 25 % in electronic components [1].
But “electronics” covers very different processes. Some electronic glass is never polished; some is polished with cerium oxide only at an intermediate step; some uses a different class of ceria product altogether. This article goes through each segment using patents, producer documentation and research publications.
1. Cover glass: polishing serves strength as well as appearance
A typical cover glass process runs from cutting and CNC shaping (drilling, edging, chamfering) to chemical strengthening, printing and coating. Polishing is done with pads and polishing powder whose “main component … is cerium oxide”, with particles of about 2 microns, according to a display manufacturer’s process description [2].
Glass producers’ own patents show the same practice. In an AGC (Asahi Glass) patent on the production of chemically strengthened glass, the glass is polished with a slurry in which “cerium oxide having an average particle diameter (d50) of 1 μm is dispersed in water”. The patent also explains why surface condition matters: removing the surface layer that contains scratches and fine irregularities reduces “the defects that are the starting point of the failure” [3].
The implication for a cover glass line is direct: the surface left by polishing is not only what the user sees. It is where a fracture starts.
2. Display glass: not everything is polished
Display glass illustrates why the question “what is polished?” must come first. Corning states that glass formed by its fusion process “requires no subsequent surface grinding or polishing”, which is why fusion became a reference technology for large LCD substrates [4]. At the same time, display panels and liquid crystal displays remain among the listed uses of ceria polishing powder [1].
Both facts hold. Before any trial, the first step is therefore to establish which stage of a given display process actually uses a polishing slurry, on which glass, and against which specification.
3. Glass substrates: where specifications are tightest
Hard-disk glass substrates
A Hoya patent describes the polishing sequence for magnetic-disk glass substrates in two steps. The first polishing, intended to remove “cracks or strains remaining” from lapping, uses “10 wt % cerium oxide (average particle size: 1 μm)”. The final mirror polishing uses colloidal silica and targets an arithmetic average roughness Ra of 0.20 nm or less [5]. Cerium oxide is the removal step; it is not the finishing step.
This is a concentrated market. In July 2026, TrendForce described Hoya as “the world’s sole supplier of HDD glass substrates”, investing approximately ¥50 billion in a new plant in Vietnam scheduled to start operations in 2028, as AI data centres revive demand for high-capacity drives [6].
Glass substrates for advanced packaging
Glass is also entering semiconductor packaging. In September 2023, Intel announced glass substrates for next-generation advanced packaging, citing “ultra-low flatness and better thermal and mechanical stability”, with delivery planned for “the second half of this decade” [7].
4. What this article is not about: wafer-level CMP
Ceria is also used in semiconductor chemical mechanical polishing, notably for shallow trench isolation, because of its “high polishing selectivity for SiO2/Si3N4” [8]. That field relies on ceria nanoparticles made by dedicated synthesis routes [8], whereas the grades documented for glass polishing in this article are around 1 to 2 µm [3][5][9]. The two should not be confused when comparing products.
5. The benchmark: what established producers publish
Established producers document their grades by application and particle size. Resonac, for example, markets its SHOROX cerium oxide abrasives for “glass substrates, optical glasses, hard disk glass plates, photomasks, and others”, with grades from 0.9–1.1 µm for precision finishing to 1.1–2.1 µm for general use, offered “from powder forms to slurry types” [9]. These figures are consistent with the 1 µm ceria cited in the AGC and Hoya patents [3][5].
For a buyer, this sets the standard of documentation to expect from any source: a stated particle size range per grade, a defined application, and a choice between powder and ready-to-use slurry.
6. The lesson of 2011: slurry is an asset to manage
After the rare-earth price spike of 2011, the industry changed how it uses polishing powder. According to the 2018 review, more efficient processes — shorter polishing times, smaller amounts of slurry and slurry re-use — decreased polishing powder consumption by 30–50 % [1]. Recycling technologies have also been developed: Konica Minolta describes a process that separates polishing powder from used slurry and restores it, stating that “the performance of restored particles is equivalent to that of the original polishing powder” [10].
The price risk has not disappeared. The US Geological Survey reports cerium oxide (99.5 % minimum) at US$1.21/kg in 2024 and US$1.71/kg in 2025 [11]. Cerium and lanthanum are not covered by China’s April 2025 export controls, which concern samarium, gadolinium, terbium, dysprosium, lutetium, scandium and yttrium [11].
7. Scratches, the coarse tail and slurry format
Research at Lawrence Livermore National Laboratory shows that scratch density increases exponentially with the size of a small number of oversized “rogue” particles — dried ceria agglomerates included [12] — and that final roughness is governed by the coarse tail of the particle size distribution, not by its average [13]. In the laboratory’s published polishing protocol, chemical stabilisation of the slurry combined with an engineered filtration system reduced large particles and the corresponding scratches [14].
This is why the format of supply matters in electronics. A dry powder leaves dispersion to the user; a ready-to-use slurry arrives already dispersed. In both cases, the points to control are the same: the coarse tail, agglomerates and stability over time. A typical polishing slurry contains 5–10 % solids [1].
8. Qualifying a source in electronics
| Criterion | What to request or record | Basis |
| Process step | Which step uses the slurry; glass type; specification to be met | [2][4][5] |
| Particle size | Range per grade and coarse tail (d99 or maximum), on several lots | [9][12][13] |
| Format | Powder or ready-to-use slurry; solids content; dispersion stability | [1][9][14] |
| Strength impact | Strength test results after polishing and strengthening, by polishing lot | AGC patent [3] |
| Lot documentation | Technical data sheet, certificate of analysis and safety data sheet for each lot | Good practice |
| Slurry management | Re-use and recovery options; consumption per square metre or per part | [1][10] |
Key takeaways
- Around 25 % of glass polishing powder is consumed in electronic components [1].
- Cover glass is polished with cerium oxide of about 1–2 µm; surface defects are the starting point of failure [2][3].
- Fusion-formed display glass requires no surface polishing: establish which step is polished before any trial [4].
- In hard-disk substrates, ceria is the first polishing step and colloidal silica the finishing step [5].
- Wafer-level CMP relies on ceria nanoparticles; the grades documented for glass polishing are around 1–2 µm [8][9].
- Since 2011, efficient use, re-use and recycling have cut powder consumption by 30–50 % [1][10].
Working with Illumine Consultants
Illumine Consultants supplies cerium oxide polishing compounds for electronics glass — cover glass, display glass and glass substrates — as powder or ready-to-use slurry. CERITOP is intended for consistent production; LUCERIS for tightened surface requirements. We do not ask you to requalify a line that runs well: we start from a defect, a yield issue or a second-source project, with a technical data sheet, certificate of analysis and safety data sheet for each lot.
About the author. Olivier M. is the founder of Illumine Consultants. Before founding the company, he spent eight years in rare-earth polishing solutions at Solvay. Illumine Consultants supplies cerium- and lanthanum-based polishing compounds (CERITOP and LUCERIS ranges) with an application-first approach and a documented supply chain.
This article relies exclusively on public sources, listed below. Brand names are cited for descriptive purposes only; Illumine Consultants is not affiliated with the companies mentioned.
References
[1] C. R. Borra, T. J. H. Vlugt, Y. Yang, S. E. Offerman, “Recovery of Cerium from Glass Polishing Waste: A Critical Review”, Metals 8(10), 801 (2018). doi:10.3390/met8100801.
[2] Orient Display, “Introduction to Cover Glass for Displays”. orientdisplay.com (accessed 1 Oct 2026).
[3] Patent WO2014045809A1, “Method for producing chemically strengthened glass”, Asahi Glass Co Ltd (AGC), published 27 March 2014. patents.google.com/patent/WO2014045809A1.
[4] Corning Inc., “Display Glass Manufacturing Technology” (fusion process). corning.com/worldwide/en/products/display-glass/how-it-works.html (accessed 1 Oct 2026).
[5] US Patent 9,186,771 B2, “Method of manufacturing a glass substrate for a magnetic disk and method of manufacturing a magnetic disk”, Hoya Corp, 17 November 2015. patents.google.com/patent/US9186771B2.
[6] TrendForce, “AI Data Center Demand Revives HDD; Japanese Component Makers TDK, Resonac Expand Capacity”, 22 July 2026. trendforce.com (accessed 1 Oct 2026).
[7] Intel Corporation, “Intel Unveils Industry-Leading Glass Substrates to Meet Demand for More Powerful Compute”, 18 September 2023. newsroom.intel.com.
[8] H. Dong et al., “Recent advances in synthesis of ceria nanoparticles and applications in chemical mechanical polishing”, Journal of Rare Earths 44(5), 1303–1316 (2026). doi:10.1016/j.jre.2026.02.015.
[9] Resonac, “CeO2 based polishing materials SHOROX”. resonac.com (accessed 1 Oct 2026).
[10] Konica Minolta, “Cerium oxide abrasive recycling technology”, published 24 March 2022. research.konicaminolta.com (accessed 1 Oct 2026).
[11] U.S. Geological Survey, Mineral Commodity Summaries 2026 — Rare Earths. pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf.
[12] T. Suratwala et al., “Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing”, Journal of Non-Crystalline Solids 354(18), 2023–2037 (2008). doi:10.1016/j.jnoncrysol.2007.11.015.
[13] T. Suratwala et al., “Microscopic Removal Function and the Relationship Between Slurry Particle Size Distribution and Workpiece Roughness During Pad Polishing”, Journal of the American Ceramic Society (2014). doi:10.1111/jace.12631.
[14] T. Suratwala et al., “Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres”, Journal of Visualized Experiments (2014). doi:10.3791/51965.
[15] SEMI, “SEMI Announces New Spring Schedule for SEMICON West Beginning March 30–April 1, 2027”, press release. semi.org (accessed 1 Oct 2026).
[16] Society for Information Display, Display Week 2027. displayweek.org (accessed 1 Oct 2026).
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