Science Buddies: "Ask an Expert"

why did a compound form above the vinegar when bronze, zinc coated steel and steel wire were immersed in vinegar.

What steps did you take to clean things before you started?
You need to describe your equipment, materials, steps, and observations in extreme detail for us to attempt to figure out your mysterious floating compound(s).
What kind of containers, vinegar, etc?
What did the metals look like before and after?
Did you see any bubbles at any time (size, shape, quantity, and location)?
What soap or other cleaning agent was used for the containers and equipment?

Beware, you may have a "Poly-Water" hoax http://en.wikipedia.org/wiki/Polywater The relavent portion is:

When the experiments that had produced polywater were repeated with rigorously cleaned glassware, the anomalous properties of the resulting water vanished, and even the scientists who had originally advanced the case for polywater agreed that it did not exist.

You may have "dust" accumulation in your experimental container or on the metal objects that were washed off and floated.

You may have temporarily disovled a coating off the metals only to have it separate out and float (wax, oil, lacquer, etc.).

If you put the metals in the experimental container and poured in the vinegar, you may not have noticed that there was something floating in the vinegar before you started. Even if you put the vinegar in first, you may not have left it settle and observed if there was anything floating.

We may never be able to solve this one, especially if you repeat it using clean materials and equipment and it doesn't reoccur.

And please descibe what the mysterious compounds looked like in extreme detail (color, shape, size, clumping, etc.).

I just noticed the Project Question...

why did a crusty compound form on bronz, zinc coated steel and steel wire above the metal immersed in vinegar

I interpreted

why did a compound form above the vinegar when bronze, zinc coated steel and steel wire were immersed in vinegar.

As something floating.

The project question sounds more like "Why did a crusty [crystaline] compound form on [the surface of] bronz, zinc, and steel wire in vinegar?"

Were the three metals in direct contact?
How long were they left in vinegar?
What kind of vinegar?
What color(s) is the crust / crystals?
Please describe any shape or texture of the "crust".

This sounds more like something we might be able to figure out with more details.