Metal plating and finishing: what to know

What the job involves, what changes the price, and what to ask a pro.

What metal plating and finishing is

Metal plating and finishing coat or treat metal parts with a protective or decorative layer, such as zinc, nickel, chrome or powder coat. People need it to stop corrosion, resist wear, restore a worn surface or match an appearance on parts that will be handled or exposed to weather.

Signs you need it

  • Exposed steel or iron parts have started to rust through the paint or coating on fences, railings, hardware or trailers
  • A metal part is wearing down where it rubs, such as a shaft, a hitch ball or a sliding fitting
  • You need a replacement part to match a chrome, zinc or black finish that is no longer sold
  • Brass or steel fittings on a boat, an outdoor fixture or a wheel show pitting from weather or salt air
  • A part was machined or welded and now needs a clean, uniform surface before it is coated

What the pro does

  • The finisher checks the metal type, since steel, aluminum, zinc and brass each take coatings differently
  • They strip old coating and clean the surface with cleaners, blasting or pickling so the new layer bonds
  • They apply the finish, such as an electroplated zinc or nickel layer, a powder coat or a conversion coating, with masking on threads and mating faces
  • They cure, rinse or bake the part as the finish requires and check thickness and adhesion
  • They inspect the finished part for coverage, color match and any pits, runs or missed areas before returning it

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Metal type, because aluminum, steel, brass and cast iron need different preparation and chemistry
  • Size and weight of the parts and how many fit in the tank, oven or booth at one time
  • Condition of the existing surface, since old paint, rust or scale take extra stripping and blasting
  • Finish type and thickness, such as a thin decorative chrome versus a heavy zinc or nickel layer
  • Masking of threads, bores, bearing seats and mating faces that must stay bare
  • Whether the part needs repair, such as weld build-up or straightening, before it can be coated
  • Color matching or texture requirements on powder coat

What a written quote should spell out

  • Metal type and the finish you chose, with the thickness or coating standard the finisher will use
  • Surface preparation included, such as stripping, blasting or cleaning
  • Masking, threaded holes or areas that will be left uncoated
  • Number of parts and how they are handled, racked or hung for coating
  • Curing, baking or drying time and whether the parts can be picked up the same week
  • Warranty or adhesion testing, and what happens if coating peels or misses an area

Questions to ask before you hire

  • What metal is this part, and will the finish you recommend bond to it?
  • Do you strip the old coating first, and how do you prepare threads and mating surfaces?
  • Will the finish change the fit of threads, bores or bearing seats, and how do you protect them?
  • Can you match the color or texture of my existing part, and can I see a sample?
  • Do you run the finish in-house, or do you send parts out to another shop?
  • How long will the coating last in the outdoor or salt exposure this part sees?
  • What do you do if a part comes back with runs, pits or thin spots?

Red flags

  • They quote a finish without asking what metal the part is made of
  • They do not mask threads or bearing seats, and the part will not fit after coating
  • They cannot tell you what cleaning or stripping they do before the coating goes on
  • They will not show a sample or a finished part from the same process

What you can do yourself

Do not attempt plating at home. Plating uses harsh chemical baths and produces fumes that need proper ventilation and disposal. A homeowner can scrape loose paint and wipe off dirt with a mild detergent, then bring the part to a shop. Call a finisher for any part that must hold tolerance, carry load or be plated in a bath.

Licenses and permits

Metal finishing shops are usually run as commercial businesses, and the work that involves chemical baths is often regulated for waste and worker safety. Check with your state or local licensing and environmental permitting offices for what your shop or project needs.

Metal plating and finishing questions

Can I paint metal instead of plating it?

Painting protects the surface but wears through faster on high-contact parts. Plating or a powder coat often lasts longer. Ask the finisher which option fits how the part will be used.

Will the coating change the size of the part?

Yes, a thick coating adds material. Tell the finisher which surfaces must stay exact, such as threads, press fits or sliding surfaces, so they can be masked or allowed for.

How do I check the finish before I take the part back?

Look for even coverage with no runs, bare spots or pits. Check threads and fit-up with the mating part. Ask the finisher how they test adhesion and what they will redo if the finish fails.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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