I like those invisible ink pencils/pens that expose writing under specific light, and this would be my counter-attack to printer yellow dots 
I'm not sure what you are proposing using this invisible ink for, but it tends to fade far more quickly than regular ink so would be a poor choice for backing up your seed phrase.I wish there was some physical switch that disables writing like it was with old magnetic tapes long time ago.
You do get USB drives with a physical write protection hardware switch. There are also WORM (write-once read-many) SD cards, which do exactly what they sound like.hi, try to memorise it.
You can try to memorize it if you want, but only if you also have robust hand written back ups to fall back on. If you only try to memorize your seed phrase, you will almost certainly forget it at some point and lose access to your coins.