When I was teaching (retired 3 years now) we had very large
drying racks. They operated on springs as you described.
The shelves were about 40 inches wide and there were at least
40 shelves. The brand was Rack King. I'm sure most of them
were purchased over 30 years ago, before I started teaching.
I can not imagine running an art program without one.
Woody
There is a photo on this web page of a student putting prints
on the rack.
http://www.taospaint.com/ColorPrinting.html
I've seen other teachers let students use racks in very
unproductive ways. I always emptied the rack each morning.
Period one would use the lowest levels (neatly) and we put
a card on the last shelf that class used. Period two
would use the next shelves as needed, so on and so forth.
If a class was only doing drawing, we put all those
drawings on a single shelf to save space. When we unloaded
the rack the next day it was easy to sort
by class for distribution.