What's the need for an ion trap on an aluminized picture tube

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I was looking at something and got off track and found a flier online for Sylvania aluminized picture tubes, and then again for rca aluminized picture tubes, with cross reference numbers, and a table with notes. In the notes table listed the need for an ion trap on the replacement tube, which was a new aluminized picture tube. Wikipedia says that ion traps were not needed on the new aluminized picture tubes. So can some of you who know the real poop on this please post your story on the topic. Thanks.....

From Wikipedia:
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Devices known as ion traps were used in early television receivers, prior to the introduction of aluminized CRT faces in approximately 1958. The ion trap must be delicately adjusted for maximum brightness.[8][9] The purpose of these devices was to prevent ions from discoloring the phosphor screen.[10]
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I thought this was correct.