[GreenKeys] White discoloration on keys

[AI2Q]

The white substance that sometimes forms on the plastic of the keyboard keys 
on a Model 28 is stearic acid. To my understanding, it was used as a as a 
release agent in the original molds during casting.

To remove it, direct heat from a hair dryer over the keys, then wipe and 
polish with a soft cloth. I have done this on knobs on my old national 
HRO-60, as well on plastic parts from vintage American Flyer trains from the 
1950s.

Sometimes the residue returns after a while, in which case repeated heat 
applications are required. It's quite amazing to watch the white residue 
disappear as you wave the hair dryer across the parts.

Vy 73, AI2Q, Alex
Member: ARRL, FOC, RSGB, CWops, QRP-L, Antique Wireless Association, Wide 
Area Amateur Radio Network
http://home.roadrunner.com/~alexmm