Michigan State Capital, Lansing

mscapital.jpg attached

Is anyone able to date the cleaning of the Michigan State Capital as per the
attached photograph? The scaffolding method, without safety belts or safety
lines, looks pre-OSHA. They are using rope rigs, not electric. Note the boss
man standing on the terrace above the workers.

Is anyone familiar with the use of Klenztone, ammonia biflouride, for
cleaning of sandstone?

Looking for pro & con for current project considerations.

][<en Follett