What Was QQ-P-35 And Is It Still Applicable Today?

MILITARY ∙ MEDICAL ∙ AEROSPACE ∙ ELECTRONICS ∙ SEMICONDUCTOR ∙ CONSTRUCTION

QQ-P-35 was a long used federal specification for passivation treatments on corrosion resistant steel, especially stainless steel. For many shops, engineers, machinists, and inspectors, it became familiar shorthand for a very specific idea: clean the stainless steel surface properly, remove free iron and other surface contamination, and help the material resist corrosion the way it is supposed to.

In plain English, QQ-P-35 was not a coating in the usual paint or plating sense. Passivation does not build a thick visible layer on the metal. Instead, it helps restore and improve the natural protective oxide layer on stainless steel after machining, fabrication, welding, grinding, or handling.

That matters because stainless steel can still stain, rust, or fail early if the surface has been contaminated during manufacturing.

Why QQ-P-35 Mattered

QQ-P-35 mattered because it gave manufacturers and finishers a shared standard. It told people what treatments were acceptable, what testing could be required, and what finished parts needed to achieve.

That was especially important in aerospace, defense, medical, industrial, and precision manufacturing work, where “close enough” is not good enough. A stainless steel part might look clean to the eye, but still carry embedded iron from tooling, shop dust, or handling. Passivation helps remove those problems before the part goes into service.

For many years, seeing QQ-P-35 on a drawing meant the part needed formal stainless steel passivation, not just a quick wash or polish.

Is QQ-P-35 Still Current?

The short answer is no, not in the strictest sense. QQ-P-35 is an older federal specification and has been superseded. In many modern applications, specifications such as ASTM A967 and SAE AMS2700 are now used instead.

That does not mean QQ-P-35 has disappeared from the real world. Older drawings, legacy parts, long running contracts, military documentation, and customer prints may still reference it. Many buyers and engineers still say “QQ-P-35” because that is the language they inherited from earlier projects.

So the real question is not whether the old document is current. The better question is what the customer, drawing, purchase order, and industry requirement actually call for today.

What Should Be Used Instead?

For many commercial and industrial stainless steel parts, ASTM A967 is commonly used for chemical passivation. For aerospace and other high specification work, SAE AMS2700 is often the more appropriate modern reference.

Both standards address the same broad goal as QQ-P-35: removing harmful surface contamination and confirming that stainless steel parts meet corrosion resistance expectations. The details, accepted processes, tests, and documentation requirements may vary, which is why it is important not to guess.

A good finishing partner will review the print, ask the right questions, and help determine whether the job should be processed to ASTM A967, AMS2700, or another customer specified requirement.

Why This Still Matters Today

Outdated specs can create confusion. A drawing may call out QQ-P-35, while a customer’s quality department expects a current equivalent. That can lead to delays, rejected parts, or unnecessary back and forth.

The safest path is to clarify the applicable standard before processing begins. For critical parts, that conversation should happen early, not after the parts are already finished.

Call Performance Coating

If your drawing still references QQ-P-35, or you need stainless steel passivation performed to a modern specification, Performance Coating can help you sort through the requirements and choose the right finishing process. Contact Performance Coating today to discuss your parts, specifications, and project needs.