You don't "use" the soot sack, you simply walk around and the soot sack takes care of picking up the soot for you...don't take my word for it, just go back to the guy who gave it to you and see how much you've accumulated. :)
collect soot using soot sack and exchanges for it
In Pokémon Emerald, you can obtain a Soot Sack by speaking to an NPC named the Soot Sack Man, located in the Fiery Path. After you defeat the Pokémon League, he will give you the Soot Sack, which allows you to collect Ash from Pokémon battles. This item is useful for finding hidden items and Pokémon in the Hoenn region.
It is a key item used to pick up soot when you walk through the grass. You can exchange soot for prizes.
if it is like ruby, where to find the soot sack as I recall is located in a man's pocket and the person is... the guy in the house who turns ashes into glass objects
get a sack and fill it with vegetables
You collect it automatically when you walk through the sooty grass.
To use the Soot Sack in Pokemon Ruby you simply need to walk through ash covered grass in Route 113 and the Jagged Pass. The ash is picked up automatically and can be used to make some items at the Glass Workshop on Route 113.
.936 cubic feet
You automatically use it whenever you walk over the ash covered grass. The more you walk on the ash grass the more ash you collect.
no of course not
Soot's plural is soot.
soot doors is provide to clean the outside of the water tubes and to remove the soot.