Blame the humidity. Blame the leaky roof. Both are real, and neither one explains why a bank of coin mechs in a 60-machine volunteer arcade museum pitted out in eighteen months while identical mechs two aisles over came through bright. Corrosion is a materials question before it is a weather question, which is why restoration crews around Tidewater eventually stop buying dehumidifiers and start hunting for corrosion testing va shops will accept a small box of parts for. The argument here is simple: identify the alloy and the attack that is actually eating each part, and you stop burning new-old-stock hardware you can never buy again.
Collectors Blame Humidity When The Alloy Is Guilty
Two cabinets, one room, one air handler that quit working years ago. The brass on one goes dull and soft while its neighbor stays clean, and no reading off a hygrometer accounts for the difference. Writing about brass in pump components, Industrial Monitor Direct laid out in May 2026 the conditions that drive dezincification: chloride above 250 ppm, pH under 6.5, temperature over 50C, stagnant or low-velocity flow, and standard brass running about 30 percent zinc, where the resistant grades add arsenic, antimony or phosphorus at 0.02 to 0.06 percent. A warehouse is not a pump loop and nobody should pretend those water numbers carry over. The alloy half does carry over. Dezincification is what the metals people call a selective attack, meaning the zinc leaches out and the copper stays behind as a spongy skeleton that still looks like a coin mech frame right up until the day it snaps in your hand.
Plating changes the shape of the problem rather than solving it. A nickel or chrome layer over a base metal is a barrier, so the moment it takes a pinhole you have a very small exposed anode sitting inside a very large cathode. That geometry concentrates the attack into one spot instead of spreading it thin. Job after job, the same thing turns up on the bench: parts that look ninety percent perfect with one blister quietly doing all of the damage.
Polishing Hides Damage Only Lab Analysis Measures
The myth is that a pitted part is a dirty part. Polishing takes off metal and takes off evidence in the same pass, and on a plated part it removes the last barrier the part had (yes, the wheel is everybody’s first instinct, mine very much included). A volunteer with a sisal wheel can turn a diagnosable failure into a shiny mystery in about ten minutes. A part you polished can no longer tell you why it failed. What an analyst reads instead is the cross section, the chemistry of the corrosion product and the alloy itself, which is what separates a damp-building problem from a plating defect from hardware that was simply the wrong metal for the room.
Cost math lands harder on a volunteer operation than it does on a refinery. Say the museum works from a $3,000 annual parts budget and puts $1,900 of that into replacing coin mech frames, ball guides and leg leveler hardware that keep failing the same way. Sending eight parts out once, and learning which two are the wrong alloy for a leaky building, beats funding a fourth round of replacements. The parts bin does not lie about how much of it is left.
Testing A Few Parts Saves Irreplaceable Ones
Send the parts that fail most, not the ones that look worst. Two failed originals, one survivor off the same shelf, and a note about where each one sat in the building gives an analyst something real to compare, and comparison is where the answer usually lives. Labs commonly quote three to four weeks on that sort of work, which is nothing set against a machine that has been waiting since 1979. One round of corrosion testing va crews can fit into a single year of budget will do more for a 60-machine collection than another dehumidifier ever will, because it tells the crew which parts to protect, which to substitute, and which were doomed by their own composition the day they were cast.
