It is doing what it is supposed to, the Zn is corroding to protect the steel.

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P.E. Metallurgy, consulting work welcomed

Why were these plates sprayed with that combination of chemicals?

It was a corrosion test? So can we sugest that the one sprayed with Sodium hypochlorite, was the most corroded !?

regards

Those chemicals sound like homebrew mold abatement.

Yes. Mold remediation was conducted by spraying a mold remover solution(ingredient: Sodium hypochlorite, Sodium carbonate, Sodium hydroxide) on almost the whole house during framing one year ago. So almost all connector plates were also sprayed by that chemical.
That chemical has been left on the surface on the steel plates since then. Now, most of the connector plates in the attic are like these pictures.
The attic could be humid in some circumstances and it could get a water leak during a storm. Some condensation on the roofing nails in winter has already been observed.
Will the steel part of these plates get corroded fast in this environment since Zinc is already sacrificed?
If so, how soon may it happen from your experience?
Thanks

Once thr zinc layer is gone, corrosion rate would possibly slow down. However, the steel would start to look ugly.
Apply a coat of epoxy zinc paint to enhance the steel life.

DHURJATI SEN
Kolkata, India

Do you know how long it takes to develop from Zinc corrosion(white rust) to steel corrosion(brown rust) typically?

Almost all truss connector plates of this one-year old house look like these pictures.
Is a repair required immediately to extend the longevity of the structure?
How to repair? With WD40?
Thanks.

Are you near the seacoast?
Or someplace very hot and humid?
If not then don't worry about it.
Even if the plates rust it will just look ugly. They will still work fine.
Near the sea, then I might think about giving them a brushing with a wire brush.
Just by hand to knock off any loose material.
Then painting with a Zn rich paint.
You could use a small roller.
I wouldn't worry about it though.

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P.E. Metallurgy, consulting work welcomed

Coat with Fluid Film if you're old-school or thixotropic gelled calcium sulfonate if you're new-school.

No need to brush with either coating.