Does a dark or discolored getter mean the tube is old or bad ?

A discolored getter DOES NOT MEAN a tube is bad !

Not only have people been repeating an “old wives tale”; this silly rumor has assumed such prominence among audiophiles recently that we are forced to place an announcement on our website, debunking it. The getter flashing absorbs free oxygen, nitrogen, carbon dioxide, carbon monoxide and hydrogen at all times, whether the tube is used or not. You can be certain the vacuum in a tube is bad ONLY if the flashing turns chalky white all over. This is the only case of a getter flash visually indicating a problem in the tube. If it is silver, black, rainbow-colored, or even totally gone, the tube might still work. In fact, a black getter flash is more effective than a shiny one at absorbing gas! Shown here are two Svetlana KT88s. Both of them work perfectly and test perfectly. The one on the left was rejected by a major OEM, because of complaints from their audiophile customers that the tube is “bad”.

Please allow me to quote from “Getter Materials For Electron Tubes”, by Werner Espe, Max Knoll, and Marshall P. Wilder, ELECTRONICS magazine, October 1950, page 85

“If the getter is vaporized very slowly, the first barium atoms evaporated will absorb the gas present so that the remaining getter is deposited in a very high vacuum, exhibiting a shiny mirror. If flashing is done very rapidly, however, the getter deposits in a rather high vapor pressure and the getter mirror will be discolored due to the dispersion of the barium. If vaporization is carried out in the inert atmosphere of a rare gas, the condensed deposit will be black, resulting in a dispersal getter. This condition does not mean that the getter is contaminated, but merely that the deposit is finely divided and therefore absorbs light. Such deposits exhibit higher efficiency than the bright deposits.....”

Let us make a blanket statement, to adequately cover the subject of tube viability: the only way to accurately determine the health of a tube is to test it electrically. Period. Anyone who discards a tube, because its getter flashing is slightly discolored, is wrong. (Non-flash type getters, such as those used in the SV572 or 572A, use metallic titanium or zirconium to absorb gas. They work best at high temperatures, unlike flash getters.)