Thermochromic ink on banknotes

I know of only two notes that have thermochromic ink: the 100 Latu (2007) and 500 Latu (2008) banknotes of Latvia, pre-Euro.
Thermochromic means they have one area that changes colour with heat. Just the warmth of your finger will do it.

These are the notes:

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Both of those notes are very expensive, especially if you want it in UNC which is probably what is required to demonstrate the thermochromic effect.

I want to know what other notes have this effect. I would like to get a note that is affordable for my collection. Does anyone know of such a note?

Which elements of these banknotes were made using thermochromic ink? The point is, such ink itself isn't particularly expensive, and perhaps it was used throughout the entire series?

It is the area where the denomination is, that brown rectangle

If you heat it with your finger the brown rectangle fades away and you see lots of little 500s revealed.

I first saw that on the Regula website, they show it with the 500 Latu. A friend of mine has a 100 Latu and he verified it happens with that note.

I bought a 20 Latu note from 2009. Although it has the same design with the rectangle behind the denomination, it is not thermochromic.

Thanks UVY, that would be a second place option. Do you happen to know which G&D test notes have it? My Google-Fu is failing me!

Thanks very much!
As it happens, I ordered that note about a year ago from a guy on eBay, not because of thermochromic ink (because I didn't know it had any) but because of infrared features. The note was lost the mail and I never received it.
I have been looking for it ever since.

Всем привет!
Сегодня проделал эксперимент с банкнотой 100 лат 2007 года из своей коллекции. С помощью нажатия пальцем на цифры номинала практически не удалось увидеть изменений в цвете цифр. Но вот с помощью фена получилось достичь результата. Но правда у меня различие в цвете или видимости цифр номинала было не такое контрастное как показал на прикреплённом фото uvy. При нагревании феном цифры номинала моментально бледнели, но всё же были хорошо различимы глазами.
Спасибо всем в теме за новую, весьма интересную информацию о термохромной краске на банкнотах!