Technical Clarification on Conductivity Testing and Surface Salt Assessment for Premier Sharpshot Abrasive® (PSA)

1. Introduction

Surface-soluble salt contamination is a critical factor in abrasive blasting and protective coating applications. Excessive levels of chlorides, sulphates, and nitrates may contribute to coating failure mechanisms such as:

  • Flash rusting
  • Osmotic blistering
  • Loss of adhesion
  • Premature coating breakdown

However, incorrect interpretation of conductivity-based measurements—particularly when applied to engineered mineral abrasives—can result in false contamination alarms, unnecessary abrasive rejection, and project delays.

It is therefore essential to distinguish between conductivity screening tests and actual surface salt contamination testing.

2. PSA Mineral Characteristics and Formation

Premier Sharpshot Abrasive® (PSA) is an engineered abrasive classified under ISO 11126-6 as a:

Predominantly amorphous (glassy), non-crystalline Calcium–Iron–Silicate formed from Electric Arc Furnace (EAF) slag.

PSA is produced through high-temperature EAF processing, typically exceeding:

>1400°C

During this process:

  • Raw materials are fully melted and refined
  • Volatile and unstable compounds are eliminated
  • The material is rapidly quenched into a stable glassy (amorphous) structure

As a result, PSA does not retain significant levels of water-soluble corrosive salts such as:

  • Chlorides
  • Sulphates
  • Nitrates

Independent laboratory testing has consistently confirmed these contaminants as Below Detection Limit (BDL) or Not Detected (N.D.).

3. Conductivity Behavior of PSA (Material-Specific Property)

Due to its inherent Calcium–Iron–Silicate structure, PSA may exhibit measurable conductivity during extraction testing when in contact with water (H₂O).

This conductivity is a result of:

  • Natural mineral ionic activity
  • Surface-associated mineral species
  • Intrinsic electrical behavior of the Ca–Fe–Si glass matrix

A simplified representation of the surface interaction is:

Ca ⁣ ⁣−⁠Fe ⁣ ⁣−⁠Si mineral matrix+H2O→trace ionic activity+surface hydroxylation

This interaction is:

  • Surface-limited
  • Non-aggressive
  • Chemically stable

Importantly:

This conductivity is NOT equivalent to harmful water-soluble salt contamination.

It does not indicate the presence of corrosive species that contribute to coating failure mechanisms.

4. Independent Laboratory Verification

Premier Sharpshot Abrasive® (PSA) has been independently tested by three (3) separate laboratories to evaluate harmful water-soluble salts relevant to corrosion performance.

Results consistently confirmed:

  • Chlorides: Below Detection Limit (BDL) / Not Detected
  • Water-soluble chlorides: BDL / N.D.
  • Sulphates: BDL / N.D.
  • Nitrates: BDL / N.D.

These findings confirm that PSA does not introduce significant corrosive soluble salt contamination during abrasive blasting operations.

Accordingly, conductivity values observed in PSA are attributable to its intrinsic mineral matrix and not to contamination.

For customers, inspectors, consultants, or project owners requiring supporting laboratory reports or technical verification documents, please contact us for further information and report copies.

5. Conductivity Test vs Surface Salt Contamination Test

5.1 Conductivity Test (Before Blasting)

Purpose:

  • Screening of total ionic activity in abrasive extract

Key limitations:

  • Does not identify specific ions
  • Cannot distinguish corrosive vs non-corrosive species
  • Not a direct corrosion risk indicator

Typical reference:

  • ISO 11127-6

5.2 Surface Salt Contamination Test (After Blasting)

Purpose:

  • Measurement of actual soluble salts on steel surface after blasting

Measured as:

  • mg/m² of soluble salts

Directly relevant to:

  • Coating performance
  • Corrosion risk
  • Surface acceptance criteria

Typical references:

  • ISO 8502-6
  • ISO 8502-9
  • SSPC / AMPP practices

✔ This is the true acceptance test for coating readiness

6. Industry Standards Interpretation (ISO / SSPC / AMPP)

Industry standards consistently emphasize that:

  • The critical parameter is post-blast surface contamination
  • Conductivity is a screening parameter only
  • Acceptance is based on project-specific surface salt limits

Importantly:

No ISO or AMPP standard defines conductivity of abrasive as a sole rejection criterion.

Instead, standards focus on:

  • Chloride concentration on steel surface
  • Total soluble salt levels after blasting
  • Coating system requirements
  • Service environment severity

The relevant evaluation must therefore be performed using:

  • ISO 8502-6 (Bresle extraction)
  • ISO 8502-9 (conductivity conversion to mg/m²)

7. Technical Position of PSA

Conductivity readings associated with Premier Sharpshot Abrasive® (PSA) shall be considered screening information only and must not be used as the sole basis for rejection or contamination judgment.

Assessment of PSA suitability for coating applications shall be based on:

  • Post-blast surface salt contamination testing
  • Chloride-specific evaluation
  • ISO 8502 methodology
  • SSPC / AMPP coating inspection standards
  • Project-specific coating requirements

When evaluated using proper surface salt testing methods, PSA supports effective surface preparation and long-term coating performance.

8. Technical Summary

Premier Sharpshot Abrasive® (PSA) is an engineered Calcium–Iron–Silicate abrasive produced under high-temperature EAF processing (>1400°C), resulting in a stable amorphous mineral structure.

Key conclusions:

  • Conductivity is an intrinsic material property, not contamination
  • PSA does not contain harmful soluble salts (Tested BDL)
  • Conductivity does not correlate directly with corrosion risk
  • Surface salt testing after blasting is the correct acceptance method

Therefore:

Coating readiness must be determined by post-blast surface contamination testing in accordance with ISO 8502 and SSPC / AMPP practices, not by abrasive conductivity alone.