1. its liquid type.
2. one question: why do u have to apply under the hot sun?
3. my advice is not to apply under the sun. reason: the trick of this liquid is once u apply with a soft cloth(no scrubbing) u need to let settle on the affected areas(soak) like 1min then rinse off with plenty of running water. If u were to apply under hot sun it would probably dry before the chemical can work on the stain.
4. brand?!? tarak la to be honest... if got brand it wont cost this money.
5. i dont that windscreen cleaner yr friend bought is rubbish, probably he shouldnt do under hot sun. All these chemicals are acid...and they will reaction at certain temperature on especially on brittle surfaces. even a small piece of lemon can break yr glass under hot sun.
hope this info helps.
tks.