Introduction

The quality of metalworking processes such as pickling, surface activation, electropolishing and chemical cleaning depends directly on the purity and specification of the acids used. Minimal variations in contaminant levels (such as iron, chlorides or heavy metals) can cause serious problems: staining of parts, surface pitting, discoloration of plating baths and rejection at quality inspection.

For technical buyers and procurement managers, the challenge goes beyond buying acids at the lowest price: each lot received must meet the specifications that matter for metalworking applications. The essential tool for this validation is the Certificate of Analysis (COA).

Knowing how to interpret the parameters on an acid COA and which criteria to use to validate suppliers is what separates strategic purchasing from reactive purchasing that can compromise production.

This article covers the critical parameters on COAs for industrial acids (sulfuric, hydrochloric, nitric, phosphoric) and sets out objective supplier validation criteria based on technical documentation, traceability and compliance with ISO 9001.

By the end, you will understand why serious metalworking companies do not accept acids without a lot-specific COA and how to use this documentation to approve and audit suppliers.

1. Why Acid COAs Are Critical in Metalworking Processes

1.1 The Role of Acids in Metalworking

Acids are the basis of several surface treatment and metalworking steps:

Pickling of carbon steel:

  • Removal of mill scale (iron oxides)
  • Typical acids: hydrochloric acid (HCl) or sulfuric acid (H₂SO₄)
  • Contaminant issue: staining caused by iron co-deposition

Surface activation before plating:

  • Removal of surface oxides to ensure coating adhesion
  • Typical acids: dilute sulfuric acid, hydrochloric acid
  • Contaminant issues: surface roughness (insolubles), pitting (chlorides)

Acid electrolytes in electroplating:

  • Acid copper baths, acid nickel baths, electropolishing
  • Typical acids: sulfuric acid, phosphoric acid
  • Contaminant issues: loss of brightness (organics), stains (heavy metals)

Chemical cleaning of tanks and equipment:

  • Removal of scale and carbonate deposits
  • Typical acids: hydrochloric acid, nitric acid
  • Contaminant issue: accelerated corrosion (chlorides on stainless steel)

1.2 Impact of Contaminants: Real Cases

Case 1: High iron in pickling sulfuric acid

An automotive component manufacturer found recurring staining on steel parts after pickling. A retained-sample analysis of the H₂SO₄ lot showed 18 ppm of iron (specification: max. 10 ppm). The contaminant iron co-deposited on the parts during acid activation, leaving irreversible dark stains.

Cost of the problem:

  • 3,200 parts rejected (loss of R$ 48,000)
  • Tank cleaning rework (16 hours of downtime)
  • Lot returned to the supplier

Root cause: The supplier did not maintain rigorous quality control. A generic COA (not lot-specific) hid the variation between lots.

Case 2: Chlorides in sulfuric acid for aluminum anodizing

An aluminum window frame manufacturer found pitting (localized corrosion) on anodized parts. The investigation traced the problem to a sulfuric acid lot with 12 ppm of chlorides (specification: max. 5 ppm). The chlorides caused localized attack during anodizing, compromising the oxide layer.

Cost of the problem:

  • Scrapping of 450 anodized profiles (loss of R$ 22,000)
  • Supplier requalification (audit plus additional analyses)

Lesson learned: The COA must be checked during receiving inspection before the lot is released to production.

1.3 Why a Generic COA Is Not Acceptable

Some acid suppliers provide a generic COA (typical values for the product, not specific to the lot delivered). This practice does not meet the traceability requirements of ISO 9001 and IATF 16949, for obvious reasons:

  • Lot-to-lot variation: The same manufacturer can have differences in purity and contaminants between production lots
  • No way to trace: If a nonconformity occurs, there is no way to identify which specific lot caused the problem
  • ISO 9001 audits: Auditors require evidence that each lot was validated individually

Clear position: Metalworking companies certified to ISO 9001 or IATF 16949 must require a lot-specific COA in their purchase specifications. Suppliers that do not provide one are automatically disqualified.

2. Critical Parameters on Acid COAs: What Each One Means

📝 Important Note: The technical specifications in the following tables are illustrative examples based on typical chemical industry standards for educational purposes. The actual specifications of products supplied by Boreto & Cardoso® are transcribed from certificates issued by approved manufacturers and may vary depending on the supplier of each lot. For the exact technical specifications of the products we supply, check the lot-specific COAs or contact our sales team.

2.1 Sulfuric Acid (H₂SO₄): Technical Grade

Sulfuric acid is the most widely used mineral acid in the metalworking industry, found in pickling, acid electrolytes (copper, nickel), aluminum anodizing and electropolishing.

Parameter Typical Specification Analysis Method Why It Matters
Purity (% w/w) 95.0 to 98.0% Titration The actual H₂SO₄ concentration affects pickling rate, bath pH and dilution calculations
Residue on evaporation Max. 0.02% Gravimetry Insoluble residues cause bath turbidity and surface defects on parts
Chlorides (as Cl) Max. 5 ppm Argentometry CRITICAL: Causes localized corrosion (pitting) on stainless steel and anodized aluminum
Iron (Fe) Max. 10 ppm Colorimetry CRITICAL: Contaminates electrodeposition baths, causes dark stains on plated parts
Heavy metals (as Pb) Max. 5 ppm Colorimetry Affect the quality of plated coatings (adhesion, brightness, corrosion resistance)
Arsenic (As) Max. 0.1 ppm Spectrophotometry Toxic contaminant, affects the quality of electrodeposition baths
Appearance Colorless liquid Visual Color indicates organic or metallic contamination
Density at 20°C (g/cm³) 1.83 to 1.84 Hydrometer Quick confirmation of concentration (density × purity correlation)
Oxidizing substances (as O) Max. 0.01% Titration Residual oxidizers affect the stability of plating baths

Practical interpretation for buyers:

  • Purity 95 to 98%: Standard commercial concentration for concentrated H₂SO₄. Purity below 95% indicates dilution or off-spec manufacturing.
  • Iron < 10 ppm: Critical parameter for electroplating. Stricter specifications require < 5 ppm for copper and nickel baths.
  • Chlorides < 5 ppm: Essential for aluminum anodizing and stainless steel treatment (pitting).
  • Density 1.83 to 1.84 g/cm³: Quick check during receiving inspection (hydrometer).

2.2 Hydrochloric Acid (HCl): Technical Grade

Hydrochloric acid is the acid of choice for pickling carbon steel (mill scale removal), surface activation and pH adjustment in acid baths.

Parameter Typical Specification Analysis Method Why It Matters
Purity (% w/w) >32% Titration The actual HCl concentration affects pickling efficiency and acid consumption
Residue on evaporation Max. 0.005% Gravimetry Residues cause stains and surface defects on pickled parts
Sulfates (as SO₄) Max. 10 ppm Turbidimetry Sulfates can cause precipitation of insoluble salts in baths
Iron (Fe) Max. 5 ppm Colorimetry CRITICAL: Contaminates plating baths, causes stains on parts
Heavy metals (as Pb) Max. 1 ppm Colorimetry Co-deposit in plating processes, affect coating quality
Appearance Colorless liquid Visual A yellowish tint indicates iron or organic contamination
Density at 20°C (g/cm³) 1.16 to 1.17 Hydrometer Quick concentration check (HCl 32% ≈ 1.16 g/cm³)

Practical interpretation for buyers:

  • Purity >32%: Standard commercial concentration for technical HCl. Industrial hydrochloric acid ranges from 32 to 37% (azeotropic form).
  • Iron < 5 ppm: Stricter than for H₂SO₄ because of its use in zinc plating (iron co-deposits easily).
  • Residue < 0.005%: Stricter limit than for H₂SO₄ (0.02%), since HCl is more volatile and tends to carry fewer solid impurities.
  • Colorless appearance: Any color (yellow, brown) indicates metallic or organic contamination: reject the lot.

2.3 Nitric Acid (HNO₃): Technical Grade

Nitric acid is used for passivation of stainless steel, activation of noble surfaces (platinum, palladium), equipment cleaning and oxidative processes.

Parameter Typical Specification Analysis Method Why It Matters
Purity (% w/w) 53 to 65% Titration Concentration affects passivation efficiency and acid attack rate
Residue on evaporation Max. 0.01% Gravimetry Residues impair passivation quality (oxide film formation)
Chlorides (as Cl) Max. 2 ppm Argentometry CRITICAL: Prevents formation of the passive film on stainless steel (localized corrosion)
Sulfates (as SO₄) Max. 5 ppm Turbidimetry Sulfates interfere with oxidative processes
Iron (Fe) Max. 3 ppm Colorimetry Contaminates surfaces during passivation (iron stains)
Heavy metals (as Pb) Max. 1 ppm Colorimetry Affect the quality of surface treatments
Appearance Colorless liquid Visual A yellowish tint indicates decomposition (NO₂ formation): degraded product
Density at 20°C (g/cm³) 1.33 to 1.40 Hydrometer Concentration check (HNO₃ 53% ≈ 1.33 g/cm³; 65% ≈ 1.40 g/cm³)

Practical interpretation for buyers:

  • Purity 53 to 65%: Commercial nitric acid. Concentrations above 65% require special controls (fuming product, strong oxidizer).
  • Chlorides < 2 ppm: Critical limit for stainless steel passivation (stricter than for H₂SO₄ and HCl).
  • Colorless appearance: Yellowish HNO₃ indicates decomposition from light or heat (NOx release): degraded product, reject it.
  • Variable density: Check the correlation between density and declared concentration (reference tables are available).

2.4 Phosphoric Acid (H₃PO₄): Technical Grade

Phosphoric acid is used in phosphating (conversion coating before painting), electropolishing, chemical polishing of stainless steel and passivation of aluminum.

Parameter Typical Specification Analysis Method Why It Matters
Purity (as H₃PO₄) (% w/w) 85.0 to 87.0% Titration Concentration affects phosphating efficiency and brightness in electropolishing
Residue on evaporation Max. 0.03% Gravimetry Residues cause defects in phosphate coatings (roughness, poor paint adhesion)
Chlorides (as Cl) Max. 5 ppm Argentometry Chlorides compromise the phosphate layer (underfilm corrosion)
Sulfates (as SO₄) Max. 10 ppm Turbidimetry Interfere with conversion coating processes
Iron (Fe) Max. 10 ppm Colorimetry Contaminates electropolishing baths (loss of brightness on stainless steel)
Heavy metals (as Pb) Max. 5 ppm Colorimetry Affect the quality of phosphate coatings
Arsenic (As) Max. 0.5 ppm Spectrophotometry Toxic contaminant, affects conversion processes
Appearance Colorless to slightly yellowish liquid Visual Strong color indicates contamination
Density at 20°C (g/cm³) 1.68 to 1.70 Hydrometer Concentration check (H₃PO₄ 85% ≈ 1.69 g/cm³)

Practical interpretation for buyers:

  • Purity 85 to 87%: Standard commercial concentration for technical H₃PO₄ (syrupy, viscous form).
  • Chlorides < 5 ppm: Critical for phosphating (pre-paint conversion coating): chlorides cause underfilm corrosion.
  • Iron < 10 ppm: Important in stainless steel electropolishing (loss of mirror finish).
  • Density 1.68 to 1.70 g/cm³: H₃PO₄ is very dense and viscous, which makes physical verification at receiving easy.

3. How to Use the COA for Incoming Material Validation (ISO 9001 Clause 8.6)

3.1 COA-Based Receiving Inspection Procedure

ISO 9001:2015, clause 8.6 (Release of products and services) requires organizations to verify that externally provided products meet requirements before releasing them for use. For industrial acids, the COA is the central tool for this verification.

Typical 3-step procedure:

Step 1: Document Check (100% of lots)

Before the product is even unloaded, check:

  • ✅ Does the COA accompany the product? (delivered with the invoice (nota fiscal) or sent by e-mail)
  • ✅ Lot number on the COA = lot number on the package? (physical check)
  • ✅ Manufacturing date within shelf life? (acids have a shelf life: H₂SO₄: 12 months, HCl: 12 months, HNO₃: 6 months typical)
  • ✅ Were all critical parameters analyzed? (compare with the purchase specification)
  • ✅ Are the results within the purchase specification? (parameter by parameter)
  • ✅ Does the COA identify the responsible chemist? (name, CRQ registration (Brazil's Regional Chemistry Council), signature or equivalent)
  • ✅ Is the supplier approved? (check the approved supplier list)

If any item fails: Hold the lot, do not unload, contact the supplier immediately.

Step 2: Physical Check (100% of lots)

After unloading:

  • ✅ Packaging intact, with no leaks or tampering? (drums, jerrycans, IBCs)
  • ✅ Security seal intact? (if applicable)
  • ✅ Labeling compliant with ABNT NBR 14725-3 (Brazilian technical standard for GHS hazard communication)? (pictograms, hazard statements)
  • ✅ Quantity received = quantity ordered? (count of packages)
  • ✅ Visual appearance consistent with the product? (color and physical state as stated on the COA)
  • ✅ Lot identification visible on the package? (label, printing, marking)

If any item fails: Segregate the lot, notify the supplier, evaluate a return.

Step 3: Analytical Check (sampling based on criticality)

Depending on the criticality of the acid and the supplier's track record, run verification analyses on a retained sample:

Critical products (analysis on 100% of lots):

  • Sulfuric acid for aluminum anodizing (check chlorides)
  • Hydrochloric acid for plating (check iron)
  • Nitric acid for stainless steel passivation (check chlorides)

Non-critical products (sampling 1 in every 5 lots, or based on track record):

  • Acids for general cleaning
  • Acids from suppliers with an established record of conformity

Typical verification analyses:

  • Density (hydrometer: quick test, 5 minutes)
  • pH (pH meter: for dilute acids)
  • Purity (titration: in-house or external laboratory)
  • Iron (colorimetry: external laboratory or colorimetric kit)

Inspection result:

  • APPROVED: Lot released for production use (green label)
  • APPROVED WITH RESTRICTION: Released for less critical processes (yellow label)
  • ON HOLD: Awaiting verification analysis or clarification from the supplier (yellow label)
  • REJECTED: Returned to the supplier, nonconformity opened (red label)

3.2 Acceptance Criteria Based on the Purchase Specification

The internal purchase specification should define acceptance criteria stricter than the supplier's generic specification whenever the process calls for tighter control.

Example: Internal Purchase Specification for Sulfuric Acid for Steel Pickling

Parameter Supplier Specification Internal Acceptance Criterion Rationale
Purity (%) 95.0 to 98.0% 96.0 to 98.0% Tighter control of pickling rate (automated process)
Iron (ppm) Max. 10 ppm Max. 5 ppm Prevent contamination of downstream baths (plating)
Chlorides (ppm) Max. 5 ppm Max. 5 ppm Same as supplier specification (adequate for the application)
Density (g/cm³) 1.83 to 1.84 1.83 to 1.84 Same as supplier (quick check at receiving)
Residue on evaporation (%) Max. 0.02% Max. 0.01% Stricter (critical process under automotive quality control)
Heavy metals (ppm) Max. 5 ppm Max. 3 ppm End customer requirement (export to Europe, REACH)

Critical remark: Internal criteria can and should be stricter than the supplier's specification when:

  1. The metalworking process is critical (automotive, aerospace, medical devices)
  2. The end customer imposes additional requirements (export, specific regulations)
  3. There is a history of problems with a given contaminant

Communication to the supplier: A purchase specification with internal criteria must be formally communicated to the supplier (ISO 9001 clause 8.4.3). Include it in the purchase order or supply agreement.

3.3 Recording and Archiving COAs for Traceability

Archiving requirements under ISO 9001 and IATF 16949:

Archive format:

Physical:

  • Files organized by supplier, then by product, then by receiving date
  • Hanging folders or dead-file storage with clear indexing
  • Protection against moisture and deterioration

Digital (recommended):

  • Quality management system (QMS) or ERP
  • Automatic backup (cloud plus local)
  • Indexing by lot number, receiving date, invoice number and product code
  • Controlled access (role-based permissions)

Minimum retention period:

  • ISO 9001 (general): Life cycle of the end product plus the warranty period offered to customers
  • IATF 16949 (automotive): At least 15 years after the last production of the product
  • Pharmaceuticals, medical devices: Up to 30 years or permanent
  • Aerospace, defense: Often permanent

COA-related information that should be filed together:

  • ✅ Original COA (PDF or signed paper copy)
  • ✅ Purchase invoice (commercial traceability)
  • ✅ Receiving inspection certificate (approved/on hold/rejected)
  • ✅ Verification analysis results (if performed)
  • ✅ Lot release or rejection record (formal decision)
  • ✅ Lot consumption record (which processes or production orders used it)

Benefit of full traceability: If a nonconformity or recall occurs, you can identify within minutes which acid lot was used, when it was used and which end products it went into.

4. Objective Criteria for Validating Acid Suppliers

4.1 Seven-Criterion Validation Checklist

Criterion 1: Does the supplier provide a lot-specific COA?

  • ✅ YES: The supplier delivers a COA with the specific lot number with every delivery
  • ❌ NO: The supplier delivers a generic COA with no lot identification: DISQUALIFY

Criterion 2: Does the COA include all parameters critical to the application?

  • ✅ YES: The COA reports purity, critical contaminants (Fe, Cl, heavy metals), density and appearance
  • ⚠️ PARTIAL: The COA reports only purity and density (insufficient for critical processes)
  • ❌ NO: The COA omits critical parameters: request correction or disqualify

Criterion 3: Are the analysis methods identified?

  • ✅ YES: The COA identifies the methods (e.g. "Iron: Colorimetry ASTM D5162" or "Purity: Titration NBR 12077")
  • ⚠️ PARTIAL: The COA lists generic methods ("internal analysis")
  • ❌ NO: The COA does not identify methods: ask the supplier about its laboratory procedures

Criterion 4: Does the COA identify the responsible chemist?

  • ✅ YES: Name, CRQ (Regional Chemistry Council) number or equivalent, signature
  • ⚠️ PARTIAL: Name without CRQ (acceptable for international manufacturers)
  • ❌ NO: No responsible person identified: require correction

Criterion 5: Does the supplier hold ISO 9001 or equivalent certification?

  • ✅ YES: Valid ISO 9001:2015 certificate (manufacturer or distributor)
  • ⚠️ PARTIAL: Certification in progress (with a defined deadline)
  • ❌ NO: No certification and no plans for it: assess the criticality of the product

Criterion 6: Conformity record (last 12 months)?

  • ✅ EXCELLENT: 0 nonconformities in delivered lots
  • ⚠️ ACCEPTABLE: 1 or 2 minor nonconformities (resolved quickly)
  • ❌ POOR: 3 or more nonconformities, or 1 major nonconformity: reassess approval

Criterion 7: Supply capacity and logistics?

  • ✅ YES: Deliveries within the agreed lead time, stock availability, packaging flexibility
  • ⚠️ PARTIAL: Occasional delays (less than 10% of orders)
  • ❌ NO: Frequent delays, recurring stockouts: risk of production stoppage

4.2 Red Flags on Acid COAs

🚩 Red Flag 1: COA with inconsistent dates

  • Manufacturing date later than the analysis date
  • Expiry date inconsistent with the product's typical shelf life
  • Action: Question the supplier and request a written explanation

🚩 Red Flag 2: Results that are "too perfect"

  • Every parameter sits at the exact limit of the specification (e.g. Fe = 10.0 ppm when the limit is 10 ppm)
  • Round numbers for every parameter (e.g. Purity = 97.0%; Density = 1.84 g/cm³)
  • Suspicion: The COA may be fictitious or copied from a technical specification (not an actual analysis)
  • Action: Request an independent verification analysis

🚩 Red Flag 3: Visual appearance does not match the COA

  • The COA states "colorless liquid", but the product is yellowish (contaminated HCl or HNO₃)
  • The COA states a density of 1.84 g/cm³, but a quick hydrometer check shows 1.79 g/cm³
  • Action: Hold the lot, run a verification analysis and formally notify the supplier

🚩 Red Flag 4: Supplier resists providing the manufacturer's original COA

  • The distributor provides a transcribed COA but refuses to show the manufacturer's original COA
  • "Confidentiality" is claimed to avoid revealing the source of supply
  • Suspicion: There may be no original COA (product of doubtful origin)
  • Action: Require access to the original COA as a condition for approval

🚩 Red Flag 5: Extreme variation between successive lots

  • Lot 1: Fe = 3 ppm; Lot 2: Fe = 18 ppm (an absurd variation for the same manufacturer)
  • Indicates lack of process control at the manufacturer or mixing of supply sources
  • Action: Audit the supplier and review the approval

4.3 Supplier Audit: What to Check

For critical suppliers (high volume, high process impact), carry out an on-site audit (second party):

Items to check during the visit:

  1. Storage facilities:

    • Are acids stored in a segregated area (separate from alkalis and flammables)?
    • Secondary containment (spill containment basins)?
    • Adequate ventilation (acids release corrosive vapors)?

  2. Quality control:

    • In-house or outsourced laboratory?
    • Calibration of analytical equipment (valid certificates)?
    • Documented sampling procedures?

  3. Traceability:

    • Lot identification system (labels, codes)?
    • Archive of original COAs (physical/digital)?
    • Incoming and outgoing records by lot?

  4. Certifications:

    • Valid ISO 9001 (check the scope: does it include acid distribution)?
    • Environmental licenses (CETESB, the São Paulo state environmental agency; IBAMA, Brazil's federal environmental agency)?
    • AVCB (Fire Department inspection certificate, required in Brazil for buildings handling hazardous products)

  5. Technical team:

    • Responsible chemist with an active CRQ registration?
    • Training in handling hazardous products (NR-20, Brazil's federal standard for flammable and combustible liquids)?
    • Technical knowledge of metalworking applications?

Audit result: Formal report with approval or rejection and a deadline for corrections (if needed).

5. The Boreto & Cardoso® Difference: 53 Years of Trust in Acids with Full Traceability

5.1 Commitment to Complete Documentation

Boreto & Cardoso®, with 53 years of experience supplying specialty chemical inputs to the metalworking industry, understands how critical traceability and complete technical documentation are for metalworking companies certified to ISO 9001 and IATF 16949.

Supply practices that ensure compliance:

1. Lot-specific Certificate of Analysis

Every acid lot supplied comes with an individual COA, transcribed from the analyses performed by the original approved manufacturer. We do not use generic or outdated COAs.

What this means in practice:

  • Bought 4 drums of H₂SO₄ from the same lot? You receive 1 COA (single lot)
  • Bought 4 drums of H₂SO₄ from different lots? You receive 4 COAs (individual traceability)

2. Clear lot identification on packaging

All packages (200L drums, 50L jerrycans, 1000L IBCs) are labeled with:

  • ✅ Manufacturer's lot number (traceability back to the source)
  • ✅ Manufacturing and expiry dates (shelf-life control)
  • ✅ Boreto & Cardoso® invoice number (commercial traceability)
  • ✅ Product code (Boreto internal code for inventory management)

This identification lets the customer match the COA to the physical package without ambiguity during receiving inspection.

3. Organized archive of manufacturers' original COAs

We keep the original COAs issued by the manufacturers for every lot supplied. In the event of a customer audit or a nonconformity investigation, these original documents are available for review, preserving traceability back to the source of the analysis.

4. Approved, ISO 9001 certified suppliers

We work exclusively with approved acid manufacturers that have:

  • ✅ ISO 9001:2015 certification (quality management)
  • ✅ Laboratories with validated analysis methods (ASTM, ABNT, pharmacopoeia)
  • ✅ A conformity record (ongoing performance evaluation)
  • ✅ Environmental and health licensing (legal, regularized operation)

This approval ensures that transcribed COAs reflect reliable, traceable analyses from manufacturers with certified quality control.

5.2 Acid Portfolio for the Metalworking Industry

Technical grade acids available with a lot-specific COA:

Sulfuric Acid (H₂SO₄):

  • Concentration: 98% (technical grade)
  • Applications: Steel pickling, aluminum anodizing, acid electrolytes, alkaline neutralization
  • Packaging: 200L drums, 1000L IBCs

Hydrochloric Acid (HCl):

  • Concentration: 32% (technical grade)
  • Applications: Carbon steel pickling, surface activation, pH adjustment, chemical cleaning
  • Packaging: 50L jerrycans, 200L drums, 1000L IBCs

Nitric Acid (HNO₃):

  • Concentration: 53 to 65% (technical grade)
  • Applications: Stainless steel passivation, noble metal activation, equipment cleaning
  • Packaging: 50L jerrycans, 200L drums

Phosphoric Acid (H₃PO₄):

  • Concentration: 85% (technical grade)
  • Applications: Phosphating, electropolishing, chemical polishing of stainless steel
  • Packaging: 50L jerrycans, 200L drums, 1000L IBCs

Every acid we supply comes with:

  • ✅ Lot-specific Certificate of Analysis (COA)
  • ✅ Safety Data Sheet (SDS) updated in line with ABNT NBR 14725-4 (GHS)
  • ✅ Lot and expiry identification on the package
  • ✅ Invoice with full traceability
  • ✅ Emergency card (transport envelope per NBR 7503)

5.3 What We Do NOT Do (Transparency and Professional Ethics)

It is essential to be clear about the role of Boreto & Cardoso® in the metalworking industry's value chain:

What we do:

  • ✅ Supply industrial acids with complete technical documentation (COA plus SDS)
  • ✅ Provide information on technical specifications, storage and safe handling in line with the SDS
  • ✅ Answer questions about COA parameters and document compliance
  • ✅ Specialized sales support with technical knowledge of the portfolio

What we do NOT do:

  • ❌ Independent laboratory analysis of products (COAs are transcribed from approved manufacturers)
  • ❌ Development of pickling, electroplating or surface treatment processes
  • ❌ Technical consulting to solve problems in baths or metalworking processes
  • ❌ Bath formulation or custom technical specifications for specific processes

This clear position preserves professional ethics and avoids creating expectations for services we do not offer. Our value lies in supplying reliable acids with complete technical documentation, so that the metalworking company can maintain traceability and compliance with quality management standards.

5.4 ISO 9001:2015 Certification and Logistics

Boreto & Cardoso® is ISO 9001:2015 certified for the supply of industrial chemical inputs. This certification ensures that our processes for supplier selection, receiving inspection, storage, lot identification and shipping are controlled, documented and audited by an independent certification body.

Specialized logistics for hazardous products:

  • ✅ Own fleet and approved partners licensed to transport hazardous products (MOPP, the mandatory Brazilian training for drivers of hazardous materials)
  • ✅ Scheduled deliveries (automatic replenishment, JIT for high-consumption customers)
  • ✅ Packaging flexibility (from 50L jerrycans to 1000L IBCs)
  • ✅ Local stock availability (immediate delivery for high-turnover acids)
  • ✅ Nationwide service (Head office in São Paulo, Limeira branch)

6. Frequently Asked Questions (FAQ)

6.1 Why can't I accept acid without a lot-specific COA?

Because traceability is a mandatory requirement of ISO 9001 and IATF 16949. Without a lot-specific COA, you cannot:

  • Trace which specific lot caused a problem if a nonconformity occurs
  • Demonstrate incoming control in ISO 9001 audits
  • Meet product recall requirements (automotive sector)
  • Validate that each lot received meets the purchase specification

A generic COA has no value for traceability and puts your certification at risk.

6.2 How can I check that a COA is authentic (not forged)?

Recommended checks:

  1. ✅ Check the lot number: The number on the COA must be identical to the one printed on the package
  2. ✅ Check the responsible chemist: Name and CRQ number must be present (look up the CRQ on the Regional Chemistry Council website)
  3. ✅ Contact the supplier: Ask for confirmation of authenticity by corporate e-mail (not WhatsApp)
  4. ✅ Check the analysis methods: Identified methods (ASTM, ABNT) indicate an actual analysis
  5. ✅ Be suspicious of "perfect" results: Values that are too exact suggest a COA copied from a technical specification (not an actual analysis)

6.3 What is the difference between a transcribed COA and a COA based on the distributor's own analyses?

Transcribed COA:

  • The distributor transcribes the data from the manufacturer's original COA
  • The manufacturer's lot number is kept (traceability preserved)
  • The distributor does not perform its own analyses
  • Standard practice in chemical input distribution (lower cost, traceability to the manufacturer)

COA based on own analyses:

  • The distributor has its own laboratory
  • It performs independent analyses of each lot
  • Higher cost (passed on in the price)
  • More common among large distributors or for critical products

Both are valid as long as there is traceability and the original manufacturer is approved.

6.4 How long should I keep acid COAs on file?

It depends on the sector:

  • ISO 9001 (general): Life cycle of the end product plus the warranty period
  • IATF 16949 (automotive): At least 15 years
  • Pharmaceuticals, medical devices: 30 years or permanent
  • Aerospace: Often permanent

Check customer contract requirements and sector regulations.

6.5 What should I do if I receive acid with an out-of-spec parameter on the COA?

Procedure:

  1. Hold the lot (do not release it to production: red label)
  2. Notify the supplier immediately (formal e-mail with evidence)
  3. Record the nonconformity in the quality management system
  4. Evaluate an alternative use: If the out-of-spec parameter is not critical for a given application (e.g. acid for general cleaning), it can be released with a restriction
  5. Request return and replacement if there is no alternative use
  6. Open a corrective action with the supplier: Require a root cause investigation and preventive actions

Never use out-of-spec acid in critical processes (electroplating, anodizing, passivation).

6.6 Can I accept acid whose visual appearance differs from the COA?

NO. Visual appearance is an immediate indicator of contamination or degradation:

  • Yellowish HCl: Iron or organic contamination (the COA states "colorless")
  • Yellowish or brown HNO₃: Decomposition (NOx release): degraded product
  • Dark H₂SO₄: Organic contamination (charring)

Action: Reject the lot, notify the supplier and require replacement.

6.7 How do I validate a new acid supplier?

Recommended approval process:

  1. Request ISO 9001 certification (manufacturer or distributor)
  2. Request COAs from recent lots (check that the parameters are complete)
  3. Place a trial order (small volume)
  4. Independent verification analysis (external laboratory)
  5. Test in the actual process (pilot lot under controlled production)
  6. On-site audit (for high-volume or high-criticality suppliers)
  7. Formal approval (inclusion on the approved supplier list)

Never approve a supplier based on price alone. Document quality and traceability are elimination criteria.

7. Conclusion

Validating industrial acid suppliers is about securing predictability, traceability and compliance with quality management standards, not about picking the lowest price. Metalworking companies certified to ISO 9001 or IATF 16949 cannot accept suppliers that do not provide a lot-specific COA with complete critical parameters.

The critical parameters on acid COAs (purity, iron, chlorides, heavy metals, density, appearance) are the first line of defense against quality problems in pickling, electroplating, anodizing and surface treatment. Minimal variations in these parameters cause staining, pitting, bath discoloration and rejected parts.

Objective supplier validation criteria include:

  1. Supply of a lot-specific COA (not generic)
  2. A COA with complete critical parameters and identified methods
  3. Identification of the responsible chemist (CRQ or equivalent)
  4. ISO 9001 certification (manufacturer or distributor)
  5. Conformity record (zero or minimal nonconformities)
  6. Full traceability (manufacturer's original COA accessible)
  7. Reliable supply capacity and logistics

Boreto & Cardoso®, with 53 years of experience and ISO 9001:2015 certification, bases its supply of industrial acids on three pillars:

  1. Lot-specific COA transcribed from approved manufacturers
  2. Full traceability (original COA on file, lot identified on the package)
  3. Commitment to compliance (complete documentation: COA, SDS and invoice)

We do not promise to develop processes or solve technical electroplating problems: that is the responsibility of each metalworking company's technical team. Our role is to supply reliable acids with documentation that enables traceability, incoming validation and compliance with ISO 9001 audits.

Serious companies choose serious suppliers. And serious suppliers provide a lot-specific COA, without exception.

Note to the Reader

This article is purely informational and educational, covering the critical parameters on Certificates of Analysis (COA) for industrial acids and supplier validation criteria for metalworking companies certified to ISO 9001 and IATF 16949.

Boreto & Cardoso® operates exclusively as a distributor of industrial chemical inputs, supplying technical grade acids with complete technical documentation (lot-specific Certificate of Analysis and Safety Data Sheet). We do not perform independent laboratory analyses: our COAs are faithful transcriptions of the analyses performed by approved manufacturers, preserving traceability back to the source.

We do not offer:

  • Technical consulting for the development of pickling, electroplating or surface treatment processes
  • Troubleshooting of problems in baths or metalworking processes
  • Bath formulation or custom technical specifications
  • Laboratory analysis of products or wastewater

For technical questions about the use of acids in specific processes, we recommend consulting professionals specialized in metallurgical or chemical engineering.

📞 Contact Boreto & Cardoso®

Interested in acids supplied with a lot-specific COA and full traceability?

📧 E-mail: boreto@boreto.com.br

📞 Phone:

  • Head office (SP): +55 (11) 3931-1722 | +55 (11) 2366-6260
  • Head office WhatsApp: +55 (11) 99108-2229 | +55 (11) 94541-0088 | +55 (11) 91311-3528 | +55 (19) 97685-0233
  • Limeira branch: +55 (19) 99458-6331
  • Branch WhatsApp: +55 (19) 99557-1693

📍 Addresses:

  • Head office: R. Alagoas, 30 - Recanto Silvestre, Santana de Parnaíba - SP, 06530-245
  • Branch: R. Aratibá, 759 - Centro Industrial de Limeira (CIL), Limeira - SP, 13481-208

🕐 Business hours: Monday to Friday, 8:00 a.m. to 12:00 p.m. and 1:15 p.m. to 5:30 p.m.

Boreto & Cardoso®: 53 years supplying industrial acids with quality, traceability and commitment.