# Plastic blasting media

Granular plastic blast-media resin types, supplier-specific hardness and density data, sieve grades, and limits of stripping and qualification claims.

Reviewed: 2026-10-29

Tags: abrasives, blasting, plastic-media

## Identity and boundaries

PLASTI-GRIT **Type II urea** and **Type III melamine** both list a specific-gravity entry of **1.47–1.52 g/cm³** as printed. The Barcol hardness ranges differ, **54–62** for urea and **64–72** for melamine. [Urea TDS](https://compomat.com/wp-content/uploads/2023/10/Urea_TDS.pdf) [Melamine TDS](https://compomat.com/wp-content/uploads/2022/06/Melamine_TDS.pdf) The family also includes polyester, acrylic and Clear-Cut for stripping, deflashing or cleaning. [Composition Materials plastic blast media](https://compomat.com/plastic-blasting-media/)

The supplier describes granular media without a numerical angularity measurement. Molded vibratory media and cryogenic deflashing pellets have separate product identities. [Finishing process references](../../processes/finishing/index.md)

## Five exact resin variants

The following values belong to Composition Materials' named PLASTI-GRIT products. The sheets distinguish typical properties from a separate block labeled MILSPEC limits. The specific-gravity column preserves that block's wording and units. It is not a measured bulk density or a certificate for a delivered lot.

| PLASTI-GRIT product | Resin description in its TDS | Typical hardness as printed | Specific-gravity entry in MILSPEC block | Source |
| --- | --- | --- | --- | --- |
| Type I Polyester | Thermoset polyester | Barcol 34–42; MOH 3.0 | 1.15–1.25 gm/cu cm | [Polyester TDS](https://compomat.com/wp-content/uploads/2016/06/Polyester_TDS.pdf) |
| Type II Urea | Thermoset urea formaldehyde | Barcol 54–62; MOH 3.5 | 1.47–1.52 gm/cu cm | [Urea TDS](https://compomat.com/wp-content/uploads/2023/10/Urea_TDS.pdf) |
| Type III Melamine | Thermoset melamine formaldehyde | Barcol 64–72; MOH 4.0 | 1.47–1.52 gm/cu cm | [Melamine TDS](https://compomat.com/wp-content/uploads/2022/06/Melamine_TDS.pdf) |
| Type V Acrylic | Thermoplastic acrylic | Barcol 46–54; MOH 3.2–3.5 | 1.1–1.2, without a unit | [Acrylic TDS](https://compomat.com/wp-content/uploads/2016/06/Acrylic_TDS.pdf) |
| Type VI Clear-Cut | Thermoset poly allyl diglycol carbonate | Barcol 20–30 after 15 seconds; Rockwell M 95–100 | 1.22–1.32 gm/cu cm | [Clear-Cut TDS](https://compomat.com/wp-content/uploads/2016/06/Clear_Cut_TDS.pdf) |

Specific gravity is a ratio, whereas density has mass-per-volume units. The mixed labeling above is retained rather than silently recast. Mohs scratch hardness, Barcol indentation hardness, and Rockwell M are different measures. The table supplies no conversion between them. Except for Clear-Cut's stated dwell, these TDS hardness rows omit test method, instrument, specimen, and dwell details.

The Polyester, Urea, Melamine, and Clear-Cut sheets state that the finished product contains no inorganic fillers and receives an antistatic treatment. Acrylic's sheet also states an antistatic treatment. These are formulation claims for the named products, not a family-wide electrical-resistivity result. Each claim is limited to its linked TDS above.

Supplier ranges differ. Abrasive Supply's Polyblast PBCM table gives Type III Barcol 64–74 and Type V Barcol 46–54. Wheelabrator's July 2019 sheet gives 64–72 and 46–51 respectively. The latter lists bulk density of 0.7 g/cm³ for each of Types II, III, and V, separately from specific gravities of 1.5, 1.5, and 1.10–1.20. Packing voids are part of bulk volume. These quantities cannot be substituted for each other. [Polyblast PBCM](https://www.polyblast.com/products/plastic-blast-media/), [Wheelabrator sheet, p. 2](https://static.noricangroup.production.k4.m1.brightspot.cloud/5f/33/722d9f0643469bdb4d1ef10002fe/wd-plastic-media-eng-2019.pdf)

## Sieve grades and particle distributions

Polyblast publishes the following U.S. Standard Sieve pairs and millimeter intervals. They are supplier size labels, not mean particle diameters or complete distributions. [Polyblast particle-size table](https://www.polyblast.com/products/plastic-blast-media/)

| Sieve pair | Published interval, mm |
| --- | --- |
| 12/16 | 1.70–1.18 |
| 16/20 | 1.18–0.85 |
| 20/30 | 0.85–0.60 |
| 30/40 | 0.60–0.42 |
| 40/60 | 0.42–0.25 |
| 60/80 | 0.25–0.18 |

Wheelabrator instead prints 425 µm for sieve 40. Its sieving matrix contains numerical thresholds against individual sieves, but does not label their percentage denominator or explicitly define passing versus retained basis. That matrix is not treated here as a verified mass-retention distribution. Its sieve apertures and Polyblast's rounded intervals remain source-specific. [Wheelabrator sieving specification, p. 2](https://static.noricangroup.production.k4.m1.brightspot.cloud/5f/33/722d9f0643469bdb4d1ef10002fe/wd-plastic-media-eng-2019.pdf)

Footnotes also limit grade claims. PLASTI-GRIT Urea's TDS marks 12/16 through 60/80 listed pairs with an asterisk referring to MIL-P-85891A and MIL-DTL-85891B. Its unstarred 8/12 and minus-100 entries do not carry that footnote. The other four linked TDS use an asterisk for availability in MIL-P-85891A grade. For Clear-Cut, the starred list is only 12/16, 16/20, 20/40, and 40/60. A product family's specification claim does not automatically cover every offered size. [Urea TDS](https://compomat.com/wp-content/uploads/2023/10/Urea_TDS.pdf), [Clear-Cut TDS](https://compomat.com/wp-content/uploads/2016/06/Clear_Cut_TDS.pdf)

## Composition and antistatic evidence

PLASTI-GRIT Type III SDS CMC-001, version 3, revised 16 November 2023, lists polymerized melamine molding compound above 97 weight-%, proprietary pigment and additives below 2 weight-%, and resiSTAT antistatic agent below 1 weight-%. Its footnote withholds exact identities or percentages where proprietary or ranged. These inequalities are not an exact formulation totaling 100%. [Melamine SDS, section 3](https://compomat.com/wp-content/uploads/2023/11/Melamine_SDS.pdf)

The Urea TDS lists ash at 0.5% by weight and iron at 0.05% by weight under its MILSPEC block, rather than as a batch analysis. Clear-Cut's corresponding block prints extract content as ".24R% by weight" and conductivity as "16 mho/cm" without a test method. Those entries are not repaired into a clean concentration or a resistivity specification. [Urea TDS](https://compomat.com/wp-content/uploads/2023/10/Urea_TDS.pdf), [Clear-Cut TDS](https://compomat.com/wp-content/uploads/2016/06/Clear_Cut_TDS.pdf)

Clear-Cut's product page claims manufacture from 100% recycled materials, but provides no mass-accounting method or split between postconsumer and manufacturing scrap. This is a supplier statement, not independently verified recycled provenance for every lot. [Clear-Cut product page](https://compomat.com/type-vi-clear-cut/)

## Specification identity and qualification

DLA's public record lists active MIL-DTL-85891 revision C with Amendment 1, dated 22 June 2026. Its scope is engineered media for abrasive-blast removal of organic coatings. Section 1.2 identifies Types II, III, V, VII starch polymer, and VIII multi-plastic blends. Types I, IV, and VI are deleted in that edition. Commercial products retaining those historical numbers still exist. [DLA document record](https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=35072), [MIL-DTL-85891C with Amendment 1, pp. 1–2](https://quicksearch.dla.mil/WMX/Default.aspx?token=5801720)

Older MIL-P-85891A or MIL-DTL-85891B statements on supplier sheets are claims against those named editions. They do not demonstrate qualification against revision C. Section 3.1 requires authorization for qualified-products listing. Section 4.3 separately addresses conformance inspection and batch rejection. The specification also evaluates performance under defined test conditions. A material designation, manufacturer claim, qualification listing, lot conformance, and approval of an actual stripping process are different evidence. No supplier's current qualification listing or delivered-lot results were verified here. [MIL-DTL-85891C with Amendment 1, sections 3.1, 3.5, and 4.3](https://quicksearch.dla.mil/WMX/Default.aspx?token=5801720)

## Stripping, reuse, and compatibility limits

Wheelabrator describes Type III as its hardest, most aggressive plastic and explicitly allows minimal damage in that application description. Its Type V description says softest within its three-type offering. Neither statement ranks every plastic resin or establishes zero damage. [Wheelabrator product descriptions, p. 2](https://static.noricangroup.production.k4.m1.brightspot.cloud/5f/33/722d9f0643469bdb4d1ef10002fe/wd-plastic-media-eng-2019.pdf)

Composition Materials' stripping discussion says one media type does not suit all coating and substrate combinations. Its general no-marring claim is conditional on recommended blasting parameters. No representative trial supporting a universal finish, roughness, lack of embedding, or residue-free result was inspected. [Powder-coating removal discussion](https://compomat.com/plastic-media-blasting-for-powder-coating-removal/), [plastic abrasive media](https://compomat.com/plastic-abrasive-media/)

Polyblast advertises 100% recyclability. This describes a supplier claim about the media, without a reuse-cycle test or guaranteed service life. Recycled feedstock, recirculation through blasting equipment, and disposal of contaminated spent media are distinct questions. The Type III SDS identifies combustible-dust potential, oxidizer incompatibility, and undetermined solubility in other solvents. Its safety information is specific to the designated material and is not a quality specification for mixtures or a used-media waste classification. [Polyblast product claims](https://www.polyblast.com/products/plastic-blast-media/), [Melamine SDS, sections 2, 9, 10, 13, and 16](https://compomat.com/wp-content/uploads/2023/11/Melamine_SDS.pdf)

The following is synthesis from these source limits. Resin hardness and density help distinguish candidates, but cannot predict stripping selectivity alone. Coating adhesion, workpiece condition, particle distribution, contamination, and actual exposure conditions remain consequential. Antistatic treatment does not establish process certification. A stripped appearance does not establish downstream coating adhesion, cleanliness, or customer acceptance. This reference supplies no operating recipe, universal media life, or aircraft-process approval.

## Source versions and coverage

Reviewed 29 October 2026 PDT. The five linked PLASTI-GRIT TDS are undated one-page documents; URL upload directories are not verified issue dates. Their full property blocks, size lists, and footnotes were inspected. Wheelabrator's two-page sheet is marked 07/19 and subject to technical alteration. Polyblast and Composition Materials web pages are retrieval snapshots. The Type III SDS is version 3 from 2023. DLA's current scope and qualification provisions were inspected separately from supplier claims.

Coverage includes five named granular resins and limited supplier comparisons. Current Type VII and VIII product formulations, numerical particle-angularity tests, complete lot sieve analyses, resistivity measurements, spent-media contamination, production stripping trials, and applicable customer acceptance remain unverified. No paid standard text or supplier operating recipe is reproduced.