Readers offer solutions to RDU goop mystery

Your odds are still excellent for parking at RDU and getting away clean.

Almost 2 million cars park there every year. Fewer than 2 dozen car owners file damage claims each year after finding their cars splattered with mystery goop (see Tuesday's story with lots of reader comments) that is hard or impossible to remove. It's nasty enough to damage paint, glass and chrome, but fortunately it is relatively rare.

An RDU consultant is still working out what the cause of this problem is, and searching for a fix that won't cost hundreds of thousands of dollars.

While we wait for the report, we already have ideas from dozens of travelers and other readers from across the United States who read about the yucky stuff this week. They reported similar problems at parking garages in Florida, Wisconsin, Colorado, Tennessee, California and New York.

What is it? Here are the theories:

(a) Lime that leaches through the concrete ceiling when it rains. (b) Lime mixed with guano. (c) Calcium that leaches through the ceiling. (d) Calcium chloride. (e) Calcium carbonate. (f) Calcium bicarbonate. (g) Residue from garage-washing chemicals that leach through the ceiling. (h) Tainted concrete from China. (i) Smoke residue from an environmental cleanup near the airport - a furnace that is burning PCB-contaminated soil. (j) Your guess is as good as mine. 

And how to get it off your car? A lot of people recommend something called Lime A-Way.

I worked in the auto detail business 20 years in Denver Co, we would see that on cars and trucks all the time the murtic acid in the concrete seeps when water soaks the concrete and then drains. hence the concrete color ...

the people can simply spray lime-away ( yes the green bottle at safeway in the bathroom cleaners section) and watch it turn to smoke as it comes off with out so much as a blemish -- Danny Williams

But be careful. If you run out and buy that green bottle, be sure to read the label.

Something strong enough to remove lime, calcium and other bad bathroom stains can damage other stuff, too, if you're not careful with it.

There are complaints on the Web about Lime A-Way turning 'stainless' steel sinks and fixtures black. That should give you pause, even if your car is not a stainless-steel DeLorean DMC-12.

Meanwhile, one reader hopes the folks at our airport can solve the goop mystery -- before something bad happens.

You may want to make the local authorities aware of a similar situation we had on Long Island in Hicksville, NY a few years back. We had a Long Island Railroad town parking garage in which people would find what turned out to be concrete residue stains on cars whenever it would rain. Over time cracks in the structure began to appear, the structure was later condemned and ultimately torn down. -- Farouk Khan