Glass and porcelain
Reprocessed tea covers scented, compressed and blended products, and the material has to serve all three.
Porcelain is the material that does, and a lidded gaiwan of 100 ml is the usual form.
The lid is the important part with a scented tea, since it keeps the aroma in the cup.
Aroma is volatile and goes into the room quickly, and an open vessel speeds that up.
Scented jasmine is brewed at 90 °C, and porcelain holds that temperature well enough.
Aroma is also the reason glass is a weaker match than it looks.
Glass is perfectly neutral, but it loses heat fast and most of this category wants boiling water.
Gan pu（柑普）and compressed pu-erh both brew at 100 °C, and a thin glass cup drops below that at once.
Glass is still the right choice if you want to watch a jasmine leaf open.
Porcelain is the right choice for everything else, and it rinses clean of any fermentation smell.
Both are non porous, so neither one carries yesterday into today, which matters across three product types.
A vessel that remembers would mix a flower note into a cake, and that combination is not pleasant.
Clay
Clay is the one material that cannot serve all three halves of this category.
Absorption is the reason, and a scented tea is where the problem shows first.
A clay pot takes up the flower aroma and releases it into everything brewed afterwards.
That lasts for months, and no amount of rinsing removes it.
A jasmine pot will make every later tea taste faintly of flowers, which is rarely what you want.
Compressed pu-erh is the exception, and it is the same exception as in the dark tea category.
A zisha（紫砂）pot dedicated to ripe pu-erh builds a layer that its drinkers like.
Heat retention helps there too, since a compressed tea is slow to open.
Scented tea gets neither benefit, because it brews cooler and faster than a cake.
So one clay pot can serve half the category, and it cannot serve the other half at all.
Two pots would solve it, and two pots is more commitment than most buyers need.
Porcelain handles both halves acceptably, which is why it is the default answer.
Matching to the tea
Match by what was done to the leaf, since that defines the product more than the base tea does.
Scented tea wants a lidded vessel and a cooler brew, around 90 °C.
Compressed tea wants a vessel you can rinse in, and boiling water.
Blended and flavoured products follow whichever of those two they resemble more.
Gan pu is compressed and wants boiling water, and it also steeps for a long time.
A thermos is a fair match for it, and no other category says that as often.
Match by how long you intend to steep, because that decides the wall thickness.
A 30 second infusion wants a thin wall, and a 10 minute steep wants a thick one.
Fix the dose at 5 grams in 100 ml, and weigh it, because the pieces here are irregular.
A segment of gan pu varies between 5 and 10 grams, and a scale reading to 0.1 g settles it.
Smell the lid at every infusion and note where the flower stops, since that is the real test.
Material comes last, and it changes the cup less than the maker does.
Buying advice
Buy one lidded porcelain gaiwan of 100 ml, and it will cover the entire category.
Check the lid sits flat, because a loose one costs you aroma on every single infusion.
Check the spout pours cleanly, since a dribbling vessel loses aroma while you fumble with it.
A white interior shows the liquor, which is how a compressed tea is judged.
Check the glaze is intact and reject anything crazed or pinholed.
Avoid anything sold as zisha（紫砂）for under twenty dollars, which is slip cast and tinted.
If you buy clay at all, use it only for the compressed side and only for one thing.
Warm an empty pot and smell it before buying, and put it back if there is a chemical note.
Buy a pick as well, since compressed tea cannot be brewed without one.
It costs less than a cheap pot and it does more for the session.
Keep the rest of the money in the maker, since the gap between real and sprayed scenting is enormous.
A named maker and cheap neutral ware beat a fine pot and an anonymous leaf.