Chromium oxide polishing compound
Chromium(III) oxide abrasive identity, powder and compound variants, product-specific size claims, and limits of composition and polishing evidence.
Tags: abrasives, polishing, chromium-oxide
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Identity and scope
Nippon Chemical lists at least 99.3% Cr₂O₃ for its Abrasive Grade without a submicrometre distribution. Trend’s 2022 US Honing Compound Bar SDS lists 15–40 wt% Cr₂O₃ and 30–60 wt% alumina. Nippon Chemical grades Trend SDS, section 3 The abrasive is chromium(III) oxide, CAS 1308-38-9. ILO/WHO, ICSC 1531
| Substance | Formula and CAS | Identity boundary |
|---|---|---|
| Chromium(III) oxide | Cr₂O₃; 1308-38-9 | Trivalent chromium oxide associated with the abrasive discussed here. ICSC 1531 |
| Chromium(VI) oxide | CrO₃; 1333-82-0 | Hexavalent chromium oxide, also called chromic trioxide or chromic anhydride. Its card describes dark red material, a strong oxidant, and a human carcinogen. It is a different substance. ICSC 1194 |
Synthesis is that the oxidation state, formula, and product identity distinguish these materials more precisely than the word "chrome." A green color does not establish a compound's abrasive proportions, binder, purity, or particle distribution. Veritas, for example, describes its honing bar as a blend of chromium oxide and aluminum oxide in wax. Veritas, product 05M08.01.
Powder, bars, pastes, and suspensions
The abrasive substance and the supplied polishing preparation are different levels of description. These examples retain their producer's product boundaries.
| Form | Documented example | Limit of the evidence |
|---|---|---|
| Abrasive-grade raw material | Nippon Chemical lists Chromium Oxide, Abrasive Grade, separately from pigment and refractory grades. | Its chemistry table does not specify a submicrometre polishing distribution. Nippon Chemical, chromium oxide grades |
| Wax-bound bar | Veritas 05M08.01 contains chromium and aluminum oxides in a wax binder. | It is a mixed-abrasive preparation, not a pure Cr₂O₃ powder specification. Veritas |
| Paste | SlipaKniven describes its Swedish-made chromium oxide paste as free of aluminum oxide. | The page supplies no complete carrier formulation or quantitative purity assay. Its wording does not establish a 100% Cr₂O₃ preparation. SlipaKniven, chromium oxide paste |
| Suspension | EXTEC lists water-based chromic oxide suspensions 16795 at 0.5 µm and 16796 at 1.0 µm. | Both entries are marked discontinued, with references to replacements 16943 and 16945. This does not establish replacement chemistry or present availability. EXTEC, chromic oxide listing |
Terminology synthesis is that "paste" describes a preparation's consistency, while "slurry" or "suspension" describes particles carried in liquid. Those words alone establish neither abrasive purity nor carrier composition. Mixing a powder with liquid creates a preparation with additional properties and conditions. It does not establish equivalence to a supplier's stabilized suspension.
Grade chemistry and formulation
Nippon Chemical's undated page reports these limits. Its percentage headings do not expressly state a mass-fraction basis or analytical method. Nippon Chemical, abrasive and pigment tables.
| Nippon Chemical grade | Cr₂O₃ | SO₄ | Drying loss | Ignition loss | Residue on 45 µm sieve |
|---|---|---|---|---|---|
| Abrasive Grade | ≥99.3% | ≤0.3% | ≤0.2% | ≤0.1% | Not reported |
| Pigment G5 and G7 | ≥99.3% | ≤0.3% | ≤0.2% | ≤0.1% | ≤0.05% |
Synthesis is that a shared assay limit does not establish interchangeable polishing behavior. Sieve residue describes a retained fraction under the stated sieve condition. It does not supply a median diameter or the size of every particle below the sieve opening. The public tables leave grain morphology, submicrometre distribution, and lot-specific polishing results unresolved.
A formulated compound can have a much lower Cr₂O₃ fraction. Trend's USA Honing Compound Bar SDS, version 4.0, April 21, 2022, identifies codes U*DWS/HP/US and 12680. Section 3 lists aluminum oxide at 30–60 weight %, chromium(III) oxide at 15–40 weight %, and stearic acid at 5–10 weight %. Its footnote withholds exact concentrations as trade secrets. Section 9 reports no particle-size or particle-distribution data. Trend USA SDS, pp. 1–4.
Synthesis is that disclosure ranges do not give an exact recipe or account for every nonhazardous ingredient. Their endpoints cannot be combined as a single composition. Chemistry disclosure does not establish polishing performance or describe other green products.
Micrometres, scratch patterns, and finish
Veritas describes an average scratch pattern of 0.5 µm for 05M08.01. It attributes finishing and cutting roles to its chromium oxide and aluminum oxide blend. The page does not identify a roughness parameter or a scratch-measurement protocol. Its 0.5 µm claim is therefore not a reported Ra value or an abrasive particle-size distribution. Veritas, description, Q&A, and specifications.
Work Sharp labels SA0004803 a 0.5 micron chromium oxide stropping compound for a leather strop. The public description gives no percentile, measurement method, complete composition, or scratch-pattern definition. The matching number does not establish equivalence to the Veritas claim. Work Sharp, SA0004803.
Measurement synthesis is that 0.5 µm equals 500 nm by unit conversion. Neither notation specifies whether a value describes primary particles, agglomerates, a distribution percentile, or a scratch dimension. A percentile also needs its number, volume, or other weighting basis and test method. No maximum coarse-particle size follows from an unspecified nominal value.
ICSC 1531 gives a substance density of 5.22 g/cm³. It provides no loose or tapped powder bulk-density value. ILO/WHO, physical information. Synthesis is that substance density does not determine the mass in a loosely filled container or the abrasive concentration in a bar. Hardness, density, oxidation state, and a nominal micron label do not establish a universal removal rate, material compatibility, or finished roughness.
Applications and safety boundaries
Veritas names edge tools, carbon steel, and high-speed steel for its formulation. Its 2018 instructions also warn that the compound may remove soft metals such as brass too quickly. These are product-specific application statements, not a universal compatibility ranking for Cr₂O₃. Veritas product description, instructions, 162 INS-415_B.
ICSC 1531 states that dispersed Cr₂O₃ powder can produce harmful airborne particle concentrations and mechanical irritation of eyes and the respiratory tract. Distinguishing Cr(III) from Cr(VI) does not establish safe exposure to a supplied compound or its process debris. ILO/WHO, exposure information.
Trend's 2022 USA SDS warns about dust from buffing, but its section 2 combines irritant classification and warning labeling with statements that the product is not hazardous. Those statements remain inconsistent in the reviewed edition. It is not evidence for a universal hazard classification or safe exposure level. Trend USA SDS, pp. 1–2.
Source coverage and unresolved properties
The chemical cards carry October 2004 and April 2013 dates for Cr(III) and Cr(VI), respectively. Their online text was reviewed on October 29, 2026 PDT. The Nippon Chemical, Veritas, SlipaKniven, EXTEC, and Work Sharp pages have no explicit revision identifier. The Trend SDS is the USA edition identified above. Its claims do not automatically apply to another jurisdiction, formulation, or later lot.
Coverage synthesis is that these sources establish identities and named product descriptions, with explicit limits on their measurements. They do not establish universal speed, pressure, compound loading, scratch-free performance, mirror finish, or approved customer capability. No original comparative polishing study or lot certificate is included. A ceria polishing mechanism, a dense structural ceramic property, or an application list for another formulation does not fill those gaps.