# Rust inhibitors

Temporary rust-preventive formulations, product-specific properties, vapor protection, and the limits of corrosion-test claims.

Reviewed: 2026-10-30

Tags: chemicals, corrosion, surface-finishing

## Identity and scope

ZERUST’s **Axxanol 750** combines a contact oil film with vapor corrosion inhibition in an enclosure. **750-NV** is a separate version without VCI. [750 TDS](https://www.zerust.com/resourcefiles/infosheets/zerust-axxanol-750-technical-data-sheet/) Temporary protection covers iron and steel, and individual multimetal products can name additional substrates. [AMPP, What is corrosion?](https://www.ampp.org/technical-research/what-is-corrosion)

Compare supplied product, residual film and packaging separately. The protection claim depends on the tested combination.

Rust conversion is a separate function. Cortec describes CorrVerter as a primer that converts a rusted surface into a hydrophobic passive layer for subsequent top coating. That reactive treatment differs from temporary preservation. Synthesis. Neither a rust-removal process nor a complete permanent coating system is defined by the label "rust inhibitor." [Cortec, CorrVerter](https://www.cortecvci.com/products/vpcis-for-basic-metals-industries/corrverter-rust-converter/).

## Formulation and product distinctions

| Exact product | Supplied form and protective function | Boundary |
| --- | --- | --- |
| Cortec VpCI-377 and VpCI-377 Winterized | Water-based concentrate producing a clear, dry, hydrophobic film for indoor protection. Listed metals include carbon steel, stainless steel, galvanized steel, aluminum, and copper. | Winterized has a water and propylene glycol carrier. The two grades have separate property ranges. [PDS, pp. 1 to 2](https://www.cortecvci.com/Publications/PDS/VpCI-377.377_Winterized.pdf). |
| ZERUST/EXCOR Axxanol 750 | Ready-to-use oil with contact inhibition, a moisture barrier, and vapor corrosion inhibitor chemistry. | VCI protection depends on enclosure. Axxanol 750-NV is a separately named alternative without VCI. Packaging devices are not the supplied oil. [TDS, pp. 1 to 2](https://www.zerust.com/resourcefiles/infosheets/zerust-axxanol-750-technical-data-sheet/). |
| Cortec VpCI-368 | Solvent-based temporary wax-like coating with multimetal protection. | VpCI-368 M, VpCI-368 D, and CorShield VpCI-368 aerosol are distinct versions. The military qualification claim identifies M. [PDS, p. 1](https://www.cortecvci.com/Publications/PDS/VpCI-368.pdf). |
| ITW Pro Brands LPS 3 | Wax-base protective coating, sold in aerosol and non-aerosol forms. | US aerosol 00316 differs from non-aerosol 00322, 03128, 00305, and 00355. The TDS also lists Canadian and European product codes. [TDS, p. 1](https://www.itwprobrands.com/files/techdatasheets/LPS3-PremierRustInhibitor.pdf). |

Axxanol 750's vapor chemistry migrates to otherwise difficult-to-reach surfaces within enclosed packaging. This supplements its contact film. The TDS declaration limits protection claims to controlled internal testing on contaminant-free substrates and identifies environmental conditions, surface cleanliness, and coating thickness as sources of variation. [Axxanol 750 TDS, pp. 1 to 2](https://www.zerust.com/resourcefiles/infosheets/zerust-axxanol-750-technical-data-sheet/).

## Product properties and measurement bases

These are supplier-reported typical properties, not acceptance limits or operating settings. Missing measurement conditions remain missing.

| Product and source | Reported quantities | Measurement limits |
| --- | --- | --- |
| VpCI-377 | Nonvolatile content 40 to 47%; neat pH 7.5 to 9.5; density 1.04 to 1.10 kg/L. | Nonvolatile percentage basis and density temperature are unstated. Neat pH describes the supplied concentrate. [PDS, p. 2](https://www.cortecvci.com/Publications/PDS/VpCI-377.377_Winterized.pdf). |
| VpCI-377 Winterized | Nonvolatile content 36 to 42%; neat pH 7.8 to 8.9; density 1.05 to 1.10 kg/L. | Separate grade values, with the same missing percentage basis and measurement temperatures. [PDS, p. 2](https://www.cortecvci.com/Publications/PDS/VpCI-377.377_Winterized.pdf). |
| Axxanol 750 | Kinematic viscosity approximately 11.1 cSt at 40°C; VOC 257 g/L by EPA Method 24; flash point 80°C by ASTM D93. | These are product properties. Neither viscosity nor VOC identifies inhibitor activity. [TDS, p. 1](https://www.zerust.com/resourcefiles/infosheets/zerust-axxanol-750-technical-data-sheet/). |
| VpCI-368 | Volume solids 61%; density 0.91 kg/L; viscosity 2,000 to 5,000 cP; VOC 347 g/L; flash point 70°C. | No viscosity temperature or shear condition, density temperature, VOC method, or flash-point method is stated. [PDS, p. 1](https://www.cortecvci.com/Publications/PDS/VpCI-368.pdf). |
| LPS 3 non-aerosol, US SDS version 9.27 | Relative density 0.80 to 0.85 with water = 1; viscosity less than 20 cSt; flash point 40°C; volatile component 75% by volume. | Reference temperature, viscosity temperature, and flash-point method are unstated. VOC and supplied pH are unavailable. [SDS, section 9](https://www.itwprobrands.com/files/branddocs/29/LPS_LPS_3_Bulk_US_English.pdf). |

Synthesis. cP describes dynamic viscosity and cSt describes kinematic viscosity. Converting between them requires density at the same temperature. A relative density is dimensionless, unlike kg/L. Nonvolatile content, volume solids, volatile volume fraction, and VOC are different quantities. None alone supplies the concentration of corrosion-inhibiting ingredients or the composition of the residual film. A concentrate property cannot be assigned to a working bath or protected part.

The LPS TDS gives aerosol flash point 18°C, relative density 0.87, and VOC 62.8%, with no percentage basis identified for VOC. Its non-aerosol column has different values and no VOC value. These columns cannot be combined into one product profile. [LPS 3 TDS, p. 1](https://www.itwprobrands.com/files/techdatasheets/LPS3-PremierRustInhibitor.pdf).

## Composition and compatibility limits

The 2025 US LPS 3 non-aerosol SDS identifies light petroleum distillates, propylene glycol monobutyl ether, n-nonane, and Stoddard solvent. Section 3 gives weight ranges and states that specific identity or exact concentration information is withheld as a trade secret. It does not identify the complete protective additive system or assign an inhibition mechanism to every listed ingredient. [LPS 3 SDS, section 3](https://www.itwprobrands.com/files/branddocs/29/LPS_LPS_3_Bulk_US_English.pdf).

VpCI-377's PDS describes the product as free of nitrite and phosphate esters. That formulation claim is not a lot assay or a detection limit. The reviewed product documents do not disclose enough chemistry to attribute protection to a particular borate, carboxylate, or amine, or to establish a complete formula. [VpCI-377 PDS, p. 1](https://www.cortecvci.com/Publications/PDS/VpCI-377.377_Winterized.pdf).

Axxanol 750 can leave brownish stains, including on oil-treated cast or sintered metals touching polyethylene in hot, humid conditions. Its internal engine-oil compatibility test does not establish compatibility with every lubricant. [Axxanol 750 TDS, footnotes](https://www.zerust.com/resourcefiles/infosheets/zerust-axxanol-750-technical-data-sheet/).

Synthesis. A water barrier does not establish a water-displacement capability. A dry film does not establish paint adhesion, electrical-contact suitability, or compatibility with every elastomer and coating. Broad safety, environmental, or "free-of" language cannot establish current regulatory compliance, medical suitability, or food-contact permission for an actual part.

## Protection claims and test meaning

ASTM B117-19's public scope describes a salt-fog environment, without defining product-specific specimens, exposure durations, or result interpretation. Its public significance statement warns that natural-environment performance rarely correlates with standalone salt-spray results. This is a historical edition, not a claim about the latest edition. [ASTM B117-19, public scope and significance](https://store.astm.org/b0117-19.html).

ASTM D1748-24 concerns relative rust prevention on steel panels under high humidity. Its public significance statement limits comparisons to similar preservative systems and applications, notes variability, and does not supply a universal exposure period or service-life prediction. Only public scope material is used here. [ASTM D1748-24](https://store.astm.org/d1748-24.html).

The VpCI-368 PDS reports salt-spray and humidity results but omits the tested metal grade, rust endpoint, replicate variability, and an explicit link between each result and its film condition. Its protection-period claim therefore cannot establish service life on an arbitrary part. [VpCI-368 PDS, p. 1](https://www.cortecvci.com/Publications/PDS/VpCI-368.pdf).

The LPS TDS advertises protection up to nine months outdoors and two years indoors without defining exposure severity or a corrosion endpoint. These are bounded product claims. Its specification list also carries an explicit exception to paragraph 4.6.4 of MIL-PRF-16173E Grade 2 Class 1. [LPS 3 TDS, p. 1](https://www.itwprobrands.com/files/techdatasheets/LPS3-PremierRustInhibitor.pdf).

Synthesis. Accelerated-test hours cannot be converted into outdoor years. Packaging, surface condition, alloy, film continuity, contamination, and exposure remain part-specific. A named test or standard does not prove approval of a customer's process or a corrosion-free guarantee.

## Source versions and unresolved differences

Reviewed October 30, 2026, PDT. The English VpCI-377/377 Winterized PDS is revised July 23, 2018. [377 PDS](https://www.cortecvci.com/Publications/PDS/VpCI-377.377_Winterized.pdf).

The English VpCI-368 PDS states last reviewed January 6, 2026. [368 PDS](https://www.cortecvci.com/Publications/PDS/VpCI-368.pdf).

Axxanol 750 is English Rev A, copyright 2013 to 2025, without a revision date. [750 TDS](https://www.zerust.com/resourcefiles/infosheets/zerust-axxanol-750-technical-data-sheet/).

The English LPS TDS is undated. [LPS TDS](https://www.itwprobrands.com/files/techdatasheets/LPS3-PremierRustInhibitor.pdf). Current bulk properties here use US English SDS version 9.27, April 4, 2025. [LPS SDS](https://www.itwprobrands.com/files/branddocs/29/LPS_LPS_3_Bulk_US_English.pdf).

An older still-accessible US LPS 3 Bulk SDS, version 08, revised November 1, 2019, reports viscosity 20 to 550 cP without temperature, specific gravity 0.81 at 20°C, and VOC 75.58% under US state and federal consumer-product regulations. Those values have different units or disclosure bases from the 2025 sheet. Their disagreement is preserved; no reformulation or equivalence is established. [Historical LPS 3 Bulk SDS, sections 9 and 16](https://www.itwprobrands.com/files/branddocs/29/LPS_LPS3_Bulk_US_English.pdf).

This coverage does not establish full ingredient composition, active-inhibitor content, lot conformity, current regional regulatory status, or performance on a particular assembly. It supplies no formulation, bath-control method, application setting, or removal procedure.

## Related reference

[Surface-finishing processes](../../processes/finishing/index.md) places temporary preservation beside broader surface-treatment operations.