Choosing a zinc plating company is not like buying a commodity. The cheapest quote does not always deliver the best outcome and in the world of zinc electroplating, the gap between a technically competent supplier and one who cuts corners can mean the difference between parts that perform for years in the field and parts that rust in the box, fail a compliance audit, or trigger a costly product recall.
At Plateco, we have been processing zinc-plated parts since 1974 for automotive OEMs, agricultural equipment manufacturers, construction hardware producers, and industrial fastener suppliers across Wisconsin and the Midwest. We’ve seen what happens when manufacturers select a plating supplier based on price alone and we’ve built our business on being the alternative: a technically disciplined, ISO 9001:2015 certified zinc plating operation where on-spec performance and on-time delivery are backed by a genuine guarantee.
This guide gives you a practical framework for evaluating any zinc plating supplier including us. The ten questions that follow are the ones that separate capable, reliable plating partners from suppliers who will cost you more in quality escapes, rework, and expedite than they ever saved you on the original quote.
HOW TO USE THIS GUIDE
Work through each question with your prospective plating supplier before placing your first production order. A confident, capable supplier will welcome these questions they demonstrate that you understand what quality zinc plating requires. A supplier who deflects, gives vague answers, or can’t produce basic documentation on any of these topics is telling you something important about how they will handle your parts
THE 10 QUESTIONS
QUESTION #1 ARE YOU ISO 9001:2015 CERTIFIED — AND CAN YOU PROVE IT?
WHY IT MATTERS:
ISO 9001:2015 certification is the foundational quality management standard for commercial manufacturing suppliers. For zinc plating, it means the supplier has documented, controlled processes for bath chemistry management, equipment calibration, pre-treatment procedures, thickness measurement, passivation, and corrective action. Without it, you have no assurance that what they did on your first order is what they will do on your tenth. OEM supply chains automotive, agricultural, construction equipment typically require ISO 9001 certification as a non-negotiable baseline for any approved supplier.
WHAT GOOD LOOKS LIKE:
The supplier should be able to name their certifying registrar, provide their certificate number, and confirm the scope covers zinc electroplating. Certificates should be current (not expired) and renewable meaning they pass periodic surveillance audits, not just the initial certification. Ideally, they can produce the certificate on request without hesitation.
RED FLAG:
A supplier who says ‘we follow ISO principles’ or ‘we’re working toward certification’ is not ISO 9001 certified. This language is a polite way of saying they have no formal quality management system. For any OEM-controlled program or regulated supply chain, this is a disqualifying answer. Price should not be the override.
PLATECO ANSWER:
Plateco is ISO 9001:2015 certified through an accredited third-party registrar. Our certificate is current, our scope covers zinc electroplating, and our certification is verifiable. We provide our certificate number and registrar contact to customers on request. Surveillance audits are conducted annually; recertification audits every three years.
QUESTION #2 DO YOU RUN TRIVALENT CHROMATE CHEMISTRY ONLY — OR DO YOU STILL HAVE HEXAVALENT LINES?
WHY IT MATTERS:
Hexavalent chromate (Cr(VI)) passivation is restricted under RoHS 2, the ELV Directive, and REACH the regulatory frameworks governing most automotive, electronics, appliance, and industrial supply chains that touch European markets. A plater who still runs hexavalent chemistry alongside trivalent risks cross-contamination, incorrect bath selection, and non-compliant parts entering your supply chain without your knowledge. For any RoHS-controlled program, the correct answer is trivalent-only.
WHAT GOOD LOOKS LIKE:
The supplier should confirm, without hesitation, that they operate exclusively trivalent chromate chemistry for commercial passivation no hexavalent lines, no hexavalent capability in the facility. They should be able to provide a RoHS Compliance Certificate (Certificate of Compliance) confirming trivalent Cr(III) chemistry with every shipment, with lot-level traceability.
RED FLAG:
A supplier who says ‘we can do either’ or ‘we have both lines available’ is a compliance risk for any RoHS-controlled program. The risk is not hypothetical: mixing hexavalent and trivalent chemistry in the same facility creates the conditions for a non-compliant batch to be certified as compliant, either through human error or intentional substitution to save cost.
PLATECO ANSWER:
Plateco operates exclusively trivalent chromate chemistry for all commercial passivation work clear, yellow, and black. We do not have hexavalent lines in our facility. RoHS Compliance Certificates confirming Cr(III) chemistry with lot-level traceability are available with every shipment on request. This is not an add-on service; it is our standard operating procedure.
QUESTION #3 HOW DO YOU MEASURE AND DOCUMENT ZINC THICKNESS?
WHY IT MATTERS:
ASTM B633 specifies minimum zinc deposit thickness for each service condition (SC1 through SC4) on significant surfaces. The only way to know whether a part actually meets specification is to measure the deposit on the correct surfaces with calibrated equipment and record the results. Without thickness measurement and documentation, compliance with the service condition specification is an assumption, not a verified fact and assumptions don’t hold up under a customer audit or when parts fail early in the field.
WHAT GOOD LOOKS LIKE:
A qualified plater measures zinc thickness using calibrated XRF (X-ray fluorescence) or magnetic thickness gauging equipment on significant surfaces as defined by the specification or customer drawing. Calibration records for gauging equipment should be maintained and available. Thickness measurements should be recorded on the job traveler or a separate inspection record and available for customer review on request.
RED FLAG:
A supplier who responds to thickness questions with ‘we control the plating time and current density to hit specification’ without mentioning actual measurement on parts is not verifying compliance they’re inferring it from process parameters. Process control is necessary but not sufficient; actual part measurement is the verification step that confirms the part, not just the process, meets spec.
PLATECO ANSWER:
Plateco measures zinc deposit thickness on significant surfaces using calibrated XRF and magnetic thickness gauging, with calibration records maintained under our ISO 9001:2015 system. Thickness measurement data is recorded on the job traveler for every production run. For customers with specific documentation requirements, thickness records are available with the shipment.
QUESTION #4 CAN YOU PROCESS MY SPECIFIC PART — BARREL OR RACK, AND WHICH IS RIGHT?
WHY IT MATTERS:
Not every zinc plater has both barrel and rack processing capability, and the choice between them has real consequences for part quality and cost. Barrel plating handles high volumes of small parts efficiently but is inappropriate for large, fragile, or cosmetically critical parts. Rack plating handles larger or more complex parts with individual fixturing but costs more per pound than barrel. A plater who only has one capability may default to the wrong process for your part and the wrong process produces inferior results at the wrong price.
WHAT GOOD LOOKS LIKE:
The supplier should have a clear answer about which process is appropriate for your specific part, based on part size, weight, geometry, cosmetic requirements, and volume. They should be able to explain why not just ‘we do it in the barrel’ but ‘your part’s geometry and volume profile makes barrel the right choice for uniform coverage.’ A plater with both capabilities is better positioned to give you honest guidance than one who only has one line.
RED FLAG:
A supplier who doesn’t ask about your part geometry, size, or cosmetic requirements before recommending barrel or rack is not making an informed recommendation. The default answer of ‘we barrel everything’ from a barrel-only shop, or ‘we rack everything’ from a rack-only shop, tells you the answer is driven by what they have available, not what’s right for your part.
PLATECO ANSWER:
Plateco operates both barrel and rack zinc plating lines. Our team evaluates every new part number to determine the correct process based on geometry, specification, cosmetic requirements, and volume. We’ll tell you which process your part belongs in and explain why before the first production run. If you’re getting the wrong process from your current supplier, switching can improve quality and sometimes reduce cost simultaneously.
QUESTION #5 DO YOU HAVE EXPERIENCE WITH MY SPECIFIC OEM SPECIFICATION?
WHY IT MATTERS:
General ASTM B633 compliance is table stakes. If your customer is a major OEM John Deere, Caterpillar, Parker Hannifin, CNH Industrial, or an automotive Tier 1 their internal zinc plating specifications add requirements beyond ASTM B633: specific salt spray hour minimums, particular passivate chemistry requirements, documentation packages, PPAP requirements, or approved supplier lists. A plater who is unfamiliar with your OEM’s specification will learn on your job which means your first runs are the qualification runs, and failures come at your expense.
WHAT GOOD LOOKS LIKE:
The supplier should be able to name the OEM specifications they process to regularly, describe the differences from ASTM B633 those specs impose, and provide customer references or prior qualification documentation for those programs. For automotive programs, confirmation of current customer-specific approved supplier status (IATF 16949 registration, GM, Ford, or Stellantis approved) provides additional assurance.
RED FLAG:
A supplier who responds to OEM specification questions with ‘we can probably meet that’ or ‘send us the spec and we’ll figure it out’ has not previously processed to that specification. ‘Figuring it out’ on your first production run is not a qualification it’s a trial, and if the trial fails, your parts fail. The cost of a failed first production run under an OEM program can far exceed any pricing advantage the new supplier offered.
PLATECO ANSWER:
Plateco regularly processes parts to John Deere JDM specifications, Caterpillar CAT specifications, Parker Hannifin requirements, and major automotive Tier 1 customer specifications. Our ISO 9001:2015 quality system supports the documentation, traceability, and corrective action processes these programs require. When you share an OEM specification with us, we confirm whether it’s within our existing qualification before quoting and if it requires new qualification work, we tell you upfront.
QUESTION #6 HOW DO YOU HANDLE HYDROGEN EMBRITTLEMENT FOR HIGH-STRENGTH STEEL PARTS?
WHY IT MATTERS:
Hydrogen embrittlement is one of the most serious and most invisible risks in zinc electroplating. Parts above approximately 150 ksi tensile strength (HRC 36) absorb atomic hydrogen during acid pickling and plating; if not properly driven out through bake relief within 4 hours of plating, the result can be delayed brittle fracture under normal service loads with no visible warning. This failure mode has caused product recalls, field failures, and structural incidents. A plater who does not have a controlled, documented bake relief process for high-strength steel is a liability for any application using hardened fasteners, springs, or heat-treated components.
WHAT GOOD LOOKS LIKE:
The supplier should be able to describe their bake relief process: oven temperature (375 degrees F, plus or minus 25 degrees F), minimum bake duration (8 hours for standard cases, up to 24 hours for very high-strength steel), and the timing requirement (within 4 hours of plating completion). Oven calibration records should be maintained. Time-temperature data for each bake cycle should be recorded and available. The plater should ask about substrate hardness proactively it should not require the customer to prompt this discussion.
RED FLAG:
A supplier who is unfamiliar with bake relief requirements, cannot describe the parameters from memory, or who says ‘we bake when customers ask for it’ is treating bake relief as an optional add-on rather than a required process for any high-strength substrate. Waiting for customers to ask is not a quality system it is a reactive posture that puts parts at risk every time a hardness class is not communicated explicitly.
PLATECO ANSWER:
Plateco’s quoting process includes asking about substrate hardness for every job. For parts above HRC 36, hydrogen embrittlement relief baking is included in the process specification by default we do not wait to be asked. Our bake ovens are calibrated, time-temperature data is recorded on the job traveler, and bake relief records are available with shipment documentation. We prefer alkaline zinc bath chemistry for high-strength steel to minimize hydrogen introduction at the source.
QUESTION #7 WHAT IS YOUR ON-TIME DELIVERY PERFORMANCE — AND WHAT HAPPENS WHEN YOU MISS?
WHY IT MATTERS:
Zinc plating is often the last processing step before a part ships to the end customer or enters final assembly. A late delivery from the plater stops the line literally. On-time delivery performance is not a nice-to-have metric for a plating supplier; it is a core operational requirement. Standard lead times for commercial zinc plating run 1 to 3 business days for most work. What matters as much as the standard lead time is how the supplier handles exceptions rush orders, scheduling conflicts, large-lot delays and what accountability they accept when they miss.
WHAT GOOD LOOKS LIKE:
The supplier should be able to quote a specific on-time delivery percentage (look for 95 percent or above on standard commercial work) and describe how they handle exceptions. A meaningful on-time delivery guarantee not just a commitment, but a tangible consequence for the plater when they miss is a strong signal that the supplier stands behind their performance. Ask for customer references who can speak to delivery reliability, not just part quality.
RED FLAG:
A supplier who responds to on-time delivery questions with ‘we try our best’ or ‘we haven’t had complaints’ has neither measured their performance nor committed to a standard. Trying your best is not a supply chain commitment. In a manufacturing environment with tight schedules and customer commitments downstream, a plater who cannot quantify their on-time performance is telling you they haven’t been measuring it which usually means it is not as strong as they’d like you to think.
PLATECO ANSWER:
Plateco’s standard lead time is 1 to 3 business days for most commercial zinc plating work. Our on-time delivery commitment is backed by our operating guarantee: On Spec. On Time. Or It’s On Us. This is not a marketing phrase it is a contractual commitment to our customers that if we miss a delivery commitment on work we have accepted, we make it right. Customer references available on request.
QUESTION #8 HOW DO YOU HANDLE QUALITY ESCAPES AND CORRECTIVE ACTIONS?
WHY IT MATTERS:
No manufacturing process is perfect, and zinc plating is no exception. The question is not whether a supplier has ever shipped a non-conforming part the question is how they respond when they do. A supplier with a robust quality system will have a documented corrective action process: immediate containment, root cause analysis, corrective action implementation, verification, and prevention of recurrence. A supplier without such a system will apologize, replace the parts, and ship the same non-conformance on the next order.
WHAT GOOD LOOKS LIKE:
The supplier should describe their corrective action process by name (8D, A3, or similar), be able to explain root cause analysis methodology, and provide an example of a corrective action report (redacted if necessary) they have issued. They should also describe their containment process: what happens to suspect inventory when a quality issue is identified, and how they ensure affected parts do not ship to the customer.
RED FLAG:
A supplier who responds to quality escape questions with ‘it doesn’t happen much’ or ‘we just re-do the parts’ has no formal corrective action system. Re-doing the parts addresses the immediate symptom without fixing the process which means the same defect will recur on the next order. A supplier who cannot produce an example corrective action report has likely never completed a formal one.
PLATECO ANSWER:
Plateco’s ISO 9001:2015 quality system includes a documented corrective action process using the 8D methodology. When a quality escape occurs, we initiate immediate containment, conduct root cause analysis, implement corrective action at the process level, verify effectiveness, and provide a formal 8D report to the affected customer. We also maintain trend data to identify systemic issues before they become escapes. Our quality system is audited annually by our ISO registrar.
QUESTION #9 WHAT DOCUMENTATION CAN YOU PROVIDE — AND IS IT INCLUDED IN THE QUOTE?
WHY IT MATTERS:
Documentation requirements vary enormously across supply chains: a distributor buying commodity fasteners may need only a packing list, while an automotive Tier 1 may require a full PPAP package with material test reports, process control plans, dimensional reports, and signed IMDS entries. The risk is a supplier who quotes the plating work without the documentation, then discovers the documentation requirement after the order is placed and charges significantly more or simply cannot produce what the customer needs.
WHAT GOOD LOOKS LIKE:
The supplier should ask about documentation requirements at the time of quoting, list what is included in the standard scope, and price any additional documentation explicitly as a line item. At minimum, the following should be readily available on request: Certificate of Compliance confirming ASTM B633 service condition and trivalent passivate chemistry; lot-level traceability records; zinc thickness measurement data; and, for high-strength parts, bake relief time-temperature documentation.
RED FLAG:
A supplier who lists ‘certifications available upon request’ without specifying what certifications, or who discovers your documentation requirement after accepting the order and then prices it separately as a change order, is not managing documentation as a planned process element. Last-minute documentation scrambles produce errors, incorrect certifications, and delays often at the worst possible time, when your customer is waiting for the shipment.
PLATECO ANSWER:
Plateco’s standard documentation package includes a packing list and Certificate of Compliance confirming process specification, passivate chemistry (trivalent Cr(III)), and RoHS compliance status. Additional documentation bake relief records, thickness measurement data, PPAP elements, OEM-specific quality documentation is available and should be specified at quoting to ensure it is included in the job setup from day one. We do not price documentation as a surprise add-on.
QUESTION #10 WHAT IS YOUR GUARANTEE — AND WHAT HAPPENS IF YOU GET IT WRONG?
WHY IT MATTERS:
This question cuts to the core of the relationship: what does the supplier actually stand behind? Any supplier can promise quality before the order is placed. The ones who are genuinely confident in their process back it with something tangible a performance guarantee, a re-work policy, or a financial accountability commitment that puts real stakes behind their promises. Suppliers without a meaningful guarantee are telling you they expect some percentage of failures, and they’ve built the cost of managing those failures into the way they run their business transferring the consequences to you.
WHAT GOOD LOOKS LIKE:
The supplier should be able to articulate a specific performance guarantee: what they commit to delivering, what happens when they fall short, and how they make the customer whole when they do. The guarantee should cover both quality (spec conformance) and delivery (on-time performance). References from current customers who have experienced the guarantee being invoked and been satisfied with the outcome are the most credible validation.
RED FLAG:
A supplier who responds to the guarantee question with ‘we stand behind our work’ without specifying what that means in practice has no meaningful guarantee. Standing behind your work means different things to different people. Without specificity what you’ll do, when you’ll do it, and what the customer’s remedy is if you don’t it is a phrase, not a commitment.
PLATECO ANSWER:
Plateco’s operating guarantee is simple and specific: On Spec. On Time. Or It’s On Us. If we ship parts that don’t meet the agreed specification, or if we miss a committed delivery date on work we have accepted, we make it right at our cost. This commitment is not a marketing phrase; it is how we have operated for over five decades, and it is the reason our customers trust us with their most demanding programs. Call any of our references and ask whether we’ve made good on this commitment. We’re proud of the answer.
SUPPLIER EVALUATION SCORECARD
Use this quick-reference scorecard when evaluating zinc plating suppliers. Score each supplier from 1 (poor) to 3 (excellent) on each question. A total score of 25 or above indicates a supplier with the fundamentals to be a reliable partner; below 20 indicates significant risk.
ZINC PLATING SUPPLIER EVALUATION SCORECARD
| QUESTION | SCORE 1: POOR | SCORE 2: ACCEPTABLE | SCORE 3: EXCELLENT |
| ISO 9001 Certification | Not certified / in process | Certified but expired or limited scope | Current, full-scope certification verifiable |
| Trivalent Chemistry Only | Still runs hexavalent lines | Trivalent default but hex available | Trivalent only, confirmed in writing |
| Thickness Measurement | Process control only, no part measurement | Measures on request, informal records | Calibrated gauging, records every run |
| Barrel and Rack Capability | Single process only | Has both but defaults to one | Selects correct process per part analysis |
| OEM Specification Experience | No named OEM experience | Claims experience, no documentation | Named OEMs, prior qualification evidence |
| HE Bake Relief Process | Unaware of bake relief | Bakes on request, no formal records | Documented process, oven calibration, records |
| On-Time Delivery | No data / no commitment | Qualitative commitment only | Quantified OTD rate with guarantee |
| Corrective Action Process | Re-do parts, no root cause | Informal root cause, no documentation | Formal 8D, documented, examples available |
| Documentation Capability | Packing list only | Certs available but not specified | Full documentation menu at quoting |
| Performance Guarantee | No guarantee stated | General ‘stand behind work’ language | Specific, written, verifiable guarantee |
FINAL THOUGHT
Choosing a zinc plating company is one of those decisions that feels small until it isn’t. When everything goes right, zinc plating is invisible parts arrive on time, they look correct, they meet specification, and they protect the steel underneath them for years in the field. Nobody calls to talk about the plating. When things go wrong, the plating suddenly becomes the center of every conversation: a compliance audit, a field corrosion complaint, a fractured fastener, a missed build date because the plater didn’t deliver. The difference between those two outcomes is almost always the quality of the supplier decision made before the first order was ever placed.
The ten questions in this guide are not a gotcha test designed to trip up suppliers. They are the baseline of what a technically capable, operationally reliable zinc plating partner should be able to answer with confidence and documentation. If a supplier answers all ten clearly and backs their answers with verifiable evidence certifications, records, references, and a meaningful guarantee you have found a partner worth building a long-term relationship with. If a supplier deflects, generalizes, or cannot produce basic documentation on more than one or two of these questions, the price on their quote is almost certainly not telling the whole story.
The total cost of a zinc plating relationship is never just the price per pound. It includes the quality escapes you have to manage, the expedite charges you absorb when a supplier misses a delivery, the compliance investigations triggered by missing documentation, the engineering time spent on corrective actions, and the customer relationship damage that comes when a plating failure reaches the field. Suppliers who score well on all ten questions cost less in total, even when they are not the cheapest on the initial quote and the manufacturers who understand this distinction are the ones who build supply chains that consistently perform.
At Plateco, we have been earning that trust since 1974. We are not the right fit for every buyer we are the right fit for manufacturers who take quality seriously, who need a plating partner they can rely on across long programs with demanding specifications, and who understand that the difference between an adequate supplier and an excellent one shows up most clearly when things get difficult. If that describes you, we would welcome the conversation.
READY TO PUT US TO THE TEST?
Send us your drawing, material specification, quantity, and compliance requirements. Ask us any of the ten questions above we welcome them. You will receive a transparent, itemized quote that tells you exactly what process you’re getting, what documentation is included, and what we guarantee.
plateco.net | (608) 524-8241 | 1375 Industrial Street, Reedsburg, WI 53959
On Spec. On Time. Or It’s On Us.