# MicroPolish II alumina powder

Buehler's deagglomerated alumina powder for specimen preparation, with current and historical grades, crystal-phase distinctions and safety-document limits.

Reviewed: 2026-10-29

Tags: abrasives, metallography, specimen-preparation

Start with [Choosing MicroPolish media](choosing-micropolish-media.md) to compare product families, carriers and preparation requirements.


## Identity and purpose

Buehler lists deagglomerated **1 µm MicroPolish II** as **40-6322-016** in a **1 lb [0.45 kg]** package. The historical catalog lists **1 µm MicroPolish II C** as **40-6321-016**, **454 g**, and identifies it as alpha alumina. The current ordering table gives no crystal phase for 40-6322-016. The sources leave the replacement history unresolved. [Current product page][product] [Historical catalog, p. 40][historical]

Buehler lists the powder for final polishing of most minerals and metals and describes removal and finish qualitatively. See [Finishing process references](../../processes/finishing/index.md) for production deburring and edge requirements.

## Deagglomeration and particle-size language

Buehler’s May 2024 TECHNotes says the additional processing breaks up clusters and reduces the chance of particles larger than the nominal size. Oversized particles remain possible. The selection table identifies mechanical polishing action. [TECHNotes, p. 1][technotes]

The abrasive-size designations are not specimen roughness values or maximum-particle limits. The reviewed SDS supplies no grade-specific particle-size distribution. [US SDS, section 9][us]

## Historical grades and package codes

An older Buehler consumables catalog, preserved by distributor TrimiD, distinguishes these powders. Each is described as deagglomerated and mixable with distilled water. These historical entries do not establish current availability. [Historical catalog, printed p. 40, section 8.2][historical]

| Historical designation | Abrasive size | Catalog crystal phase | 228 g | 454 g | 2,270 g |
| --- | --- | --- | --- | --- | --- |
| MicroPolish II C | 1 µm | Alpha alumina | 40-6321-008 | 40-6321-016 | 40-6321-080 |
| MicroPolish II A | 0.3 µm | Alpha alumina | 40-6323-008 | 40-6323-016 | 40-6323-080 |
| MicroPolish II B | 0.05 µm | Gamma alumina | 40-6325-008 | 40-6325-016 | 40-6325-080 |

The masses reproduce that catalog's labels. Alpha and gamma describe different crystal forms of alumina, not different packages. Current **40-6322-016** differs from historical **40-6321-016**. The reviewed sources do not establish a formal replacement history. [Historical catalog, p. 40][historical] [Current product page][product]

The May 2024 note broadly calls MicroPolish I and II powders hard alpha alumina. That wording does not account for the historical gamma grade. The current product table does not specify the crystal phase of 40-6322-016. These sources therefore support version-specific descriptions, not a conclusion that every MicroPolish II grade is alpha. [TECHNotes, p. 3][technotes] [Historical catalog, p. 40][historical]

## Powder, suspension and neighboring products

The historical catalog separately lists MicroPolish II suspensions under **40-6361**, **40-6363** and **40-6365**. Their liquid volumes do not describe powder package masses. [Historical catalog, p. 40, section 8.1][historical]

Buehler's May 2014 quick-reference guide describes MicroPolish II with a glycol base but does not identify a powder SKU for that statement. It does not prove that the dry powder contains glycol. The same guide identifies MasterPrep as 0.05 µm non-agglomerated alumina and MasterPolish as an alumina and colloidal-silica blend. These are distinct product identities. [2014 quick-reference guide][guide]

The current product page lists MicroPolish powder and suspension as agglomerated alumina, with 0.05 µm, 0.3 µm and 1 µm options. Matching nominal sizes do not establish equivalence to MicroPolish II. [Current product page][product]

## Carrier choice and applicability

Explanatory synthesis. A powder allows the abrasive and liquid carrier to be considered separately. Buehler discusses powders when an existing suspension base is unsuitable, including water-sensitive specimens. It names nonaqueous carriers but warns that oils can reduce polishing rate. These general observations provide neither a universal mixing concentration nor demonstrated compatibility with an exact specimen. [TECHNotes, p. 3][technotes]

## Dated composition and handling evidence

These manufacturer safety documents cover multiple powder codes. A shared SDS does not establish identical particle phases or polishing performance.

| Document | Scope and disclosure |
| --- | --- |
| Archived MSDS 9103895, prepared 24 January 2004 | Names MicroPolish II and MicroPolish A, B and C powders. Includes the 40-6321, 40-6323 and 40-6325 package families. Discloses aluminum oxide, CAS 1344-28-1, at 70–100% by weight. [Archived MSDS, sections 1–2][old] |
| US SDS 1341982, version 2.0, revised 19 November 2025 | Covers MicroPolish and MicroPolish II powders, including 406322016, 406321016, 406321080, 406323016 and 406323080. Discloses aluminum oxide above 99%. Its code list omits 40-6325. [US SDS, sections 1, 3][us] |
| EU English SDS 1341982, version 3.1, revised 16 March 2026 | Lists the same powder codes and aluminum oxide above 99%. Section 9 provides no particle-size or pH value. [EU SDS, sections 1, 3, 9][eu] |

The older broad percentage range and newer disclosure do not establish a lot-linked formulation change. The newer documents do not retroactively characterize the omitted historical gamma grade. [Archived MSDS][old] [US SDS][us] [EU SDS][eu]

Both newer SDS documents report no hazard classification under their respective systems. They still specify ventilation, gloves, eye protection, suitable clothing and respiratory protection when ventilation is insufficient. These handling provisions do not validate process performance. [US SDS, sections 2, 7–8][us] [EU SDS, sections 2, 7–8][eu]

## Source coverage and limits

Reviewed **29 October 2026 PDT**. The product page is an undated retrieval snapshot. TECHNotes volume 8, issue 4, revision 1 is marked updated May 2024. The quick-reference guide is marked 05/14. The historical catalog's publication edition was not established. Its PDF creation metadata dates to November 2009, which is not proof of publication date. Relevant catalog tables and discussion, the complete technical note and the cited safety documents were inspected. [TECHNotes][technotes] [2014 guide][guide] [Historical catalog][historical]

The sources do not establish a complete grade migration history, current availability of historical variants, a universal carrier recipe, shelf life or a guaranteed finish. Generic material applicability does not establish a shop's approved settings or capability.

[product]: https://www.buehler.com/products/grinding-and-polishing/grinding-and-polishing-consumables/final-polishing-suspensions/
[technotes]: https://www.buehler.com/assets/solutions/technotes/How_to_Select_and_Use_Final_Polishing_Oxide_Media.pdf
[historical]: https://www.trimid.rs/upload/documents/buhler/Buehler%20-%20Consumables.pdf
[guide]: https://www.buehler.com/assets/posters/0514_Quick-Ref-Guide-to-Final-Polishing-Solutions.pdf
[old]: https://www.buehler.com/assets/SDS/US/Discontinued/9103895_EN_MicroPolish_ABC.pdf
[us]: https://www.buehler.com/assets/SDS/US/MicroPolish-and-MicroPolish-II-Alumina-Powder-US-English.pdf
[eu]: https://www.buehler.com/assets/SDS/EU-English/MicroPolish-and-MicroPolish-II-Alumina-Powder-EU-English.pdf