When you first try preparing your own matcha tea or matcha latte, you may notice that there are some lumps that not able to dissolve in water. Besides, when you leave the matcha tea for sometime, there is still some matcha powder fall to the bottom of the cup no matter how hard you whisked.
This happen to all matcha powder in the world, even for the top grade matcha powder. You are not seeing in some branded matcha latte drinks because either they are not prepared using pure matcha powder (but with sugared-powder) or they've prepared the matcha tea in a separate cup.
Matcha powder doesn't truly 100% dissolve in water like sugar or milk powder does. It's because matcha powder is actually very tiny bit of tea leaf, matcha powder is made from tea leaf ground into powder form. You will always find matcha powder fall to the bottom of the cup if you leave your matcha tea for too long. When you whisk the matcha, you actually create suspension of the tea leaf powder in the water, not dissolving it.
Matcha powder has slight electrostatic energy, making it clump and form lumps. Sifting it will definitely break the lumps.
Here are some tips: