Review on 🍑 Gentle Bottom Sensitive Changing: InGwest Friendly Solution by David Burns

I really like the cup and the idea, but it doesn't work as expected. I added boiling water and let it sit for a long time but it stayed black. The only thing I could get to work was to deliver hot water directly to the outside of the mug. It then turned black again as soon as I stopped pouring hot water on the outside of the mug. That's a really cool idea if it actually works as expected. The mug seems too thick for the image to be affected by the liquid in the mug, but you also don't want it to be thinner which would reduce durability.