Who this checklist is for

I'm the procurement manager at a 140-person metal finishing company. I've managed our coatings budget—roughly $320,000 a year—for the past seven years, and I've tracked every order in our cost system. This checklist is for the person who signs off on coating purchases for extrusion lines, aerospace parts, agricultural equipment, or professional powder coating work. It's not a chemistry textbook. It's a buying routine.

Before I get into the steps, one honest caveat: my experience is based on about 300 orders, mostly aluminum extrusion and steel fabrication. If you're buying certified aerospace coatings or specialty thermal spray systems, your tolerances are much tighter. I can't speak to every niche. But the checklist below is what I run before every PO, and it has saved us from a lot of rework.

The Checklist: 6 checks before you release a PO

I use this routine every time. It looks simple, but each check is designed to expose hidden costs before they land on my desk.

1. Put the substrate and service environment in writing

Before comparing prices, write down exactly what the coating has to do: base material, surface prep, exposure to chemicals, UV, temperature, abrasion. For example, an aluminum extrusion for a building facade is not the same as an extrusion for a pool fence. Both might be powder coated, but the performance requirements are not the same.

I made this mistake once. I said "standard exterior grade." The vendor heard "whatever white powder we have in the bin." We discovered the mismatch when the first batch started chalking after six months. That "cheap" learning experience cost more than the original difference.

2. Match the coating system to your process and spec

This is where specialized systems come in. For extruded aluminum, AkzoNobel extrusion coatings are one system I see specified on architectural projects. For aircraft components, AkzoNobel aerospace coatings are often tied to the part number and the approved applicator list. For agricultural equipment, agriculture thermal spray coatings are a different animal—usually a metal spray plus sealer, chosen for wear and corrosion in dirt, fertilizer, and moisture.

Do not swap one coating type for another because the price per kilo looks better. I learned that lesson the hard way when a supplier suggested a "similar" powder coating for a part that needed a specific weathering spec. It was similar right up until the warranty claim. You're not buying paint; you're buying a specified system.

3. Demand test panels before you talk discount

For professional powder coating, a test panel costs very little compared to a production run. I ask for coated samples on my actual substrate, not their standard test piece. I want a cross-hatch adhesion result, a film thickness report, and a color/gloss reading. If a vendor can't produce those, that is a red flag, no matter how low the quote is.

I have a specific memory here. The numbers said go with Vendor B—15% cheaper, similar spec. My gut said their slow email replies were a bad sign. I went with my gut. Their test panel failed adhesion, and we avoided a six-figure headache.

4. Calculate TCO, not unit price

This is the heart of my procurement policy. I compare unit price, lead time cost, and failure cost. A powder coating quote might be $2.10/kg versus $1.80/kg. That $0.30 difference looks small until you calculate that the cheaper vendor needs an extra week, and last year "one week late" caused a $4,000 expedite fee on the customer side.

My cost spreadsheet includes hidden line items: masking materials, racking, packaging, quarantine, retesting, scrap. When a supplier says "we don't charge for setup," ask what happens when the dimensions drift. Setup can be free. Rework is never free.

Use the phrase "total cost of ownership" in every vendor meeting. It changes the conversation. In my experience, the lowest quote has cost us more than the alternative in about six out of ten cases where we did not run a TCO check.

5. Check chemical resistance before you trust the datasheet

A question that keeps coming up from maintenance teams: can nitric acid dissolve metal? Yes, in many cases. Nitric acid will corrode carbon steel and zinc, and it can cause serious damage to aluminum depending on concentration and temperature. The coating is only protection if it is the right coating and it is undamaged. If you are coating equipment exposed to nitric acid or agricultural chemicals, ask the supplier for a chemical compatibility chart and test data, not a general "chemical resistant" label.

In agricultural spray applications, agriculture thermal spray coatings are often chosen for abrasion resistance, but their chemical resistance depends heavily on the sealer. I have seen a tough thermal spray coating fail because the sealer was not compatible with the fertilizer chemistry. That is the kind of hidden cost that shows up in year two, not in the quote.

6. Audit environmental and performance claims

Per FTC Green Guides (ftc.gov), environmental claims like "recyclable" or "low-VOC" need to be substantiated. I do not accept a phrase like "eco-friendly powder" without a test report. The same applies to durability claims: if they say "will last 20 years," ask for the accelerated weathering data and a warranty in writing.

This is also a good time to be clear: value does not mean premium every time. It means the cheapest option that meets the spec, plus the vendor's reliability. I'm not against saving money. I'm against saving money in the wrong place.

Common mistakes I still see

  • Treating the coating as a commodity and buying on price alone.
  • Not specifying the substrate prep, or letting the vendor decide for you.
  • Forgetting that a coating system includes the cure cycle and pretreatment, not just the powder or liquid.
  • Being vague about delivery dates and expedite costs—then paying the surprise difference.
  • Believing a marketing sheet instead of asking for test data.

Looking back, I should have written the chemical exposure list before our first agricultural equipment order. At the time, the spec sheet seemed clear enough. It wasn't. Now I send every vendor a one-page service environment sheet before requesting a quote. It filters out about 30% of them before they waste our time.

Bottom line: a coating purchase is not a spot buy. It's a decision about your product's reputation. Run the checklist, get the evidence, and let the spreadsheet drive the decision. If the numbers point to the more expensive option because the cheap one has a failure history, that's not a budget problem—that's an investment in not doing the job twice.