Thanks for the answers! Today I bought a jar of American Crew "Fiber". The fill weight is 100g, there is no volume indication only a weight indication. I believe it also exists in a smaller variant but my supermarket only had this.
Anyways, the stuff is very hard. I am quite convinced it counts as a solid. I'd say it is about as hard or harder (doesn't melt as easily) as a lip balm stick. You need to scoop it out with the fingernail as the tip of the finger won't get much. You then need to rub it vigorously in your hands to make it soft. A green pea size amount is sufficient for my hair on dry hair. My hair is fine and I am somewhat balding, though. If you have a wire brush on your head you might need more. It does make the hair feel a bit greasy at least when applied to dry hair. The directions say to apply to towel dry hair. I will try that tomorrow.
I bought this over the clay they offered because the clay didn't smell very good. It actually did smell a bit like clay because there is effectively real clay in it. the Fiber stuff smells quite nice. A bit lemony and cedary.
So this stuff is going with me on my trip next week. We'll see. I will also take some shaving oil. The tiny 0.5 Alpha oil container. I shall try both version: 1. Smuggled in my pants and 2. not in a kippie but just put openly in the bin.
In that case, all they could say is that it must be in a baggie. That is kind of stupid though for a single item.
I'll let you know how it went.
Till