[Ernest_at_the_Beach]

In recent years, the flaking problem has become more common as NASA. Contractors changed the composition of the spray-on foam and adhesives to comply with health and environmental regulations, said Alfred F. Daech, a former consultant with Martin Marietta, now part of Lockheed Martin. Chromium and freon were removed.

Why do you worry about environmental aspects on a container of very non-environmental caustic liquid?

Stupidity in regulations!

[Ben Hecks]

"very non-environmental caustic liquid?"

The External Tank is filled with liquid hydrogen and liquid oxygen; the small amount of hydrazine and nitrogen tetroxide used for the RCS system is carried inside the shuttle. Just as a note, the first External Tanks were painted white. To save money and weight, painting was discontinued and the tanks are left with the natural reddish orange color of the insulation.