For a long time I thought it is impossible, but thanks to TibiaHome (fansite dedicated to tibian houses deco) and @skicior I found a solution.
It is possible to farm Glooth Farinas and gather as many of them as you want.
All you need to do is to take mission "The Gloud Ship" from Zeronex or task Cooking Gloo if you have already done whole mission before.
Then if Glooth Cauldron needs Glooth Farina you simply take it from the bookcase. And now, you have to take farina out of the backpack, go back to the Glooth Cauldron, click it again - then go back to the bookcase and take another farina. You can repeat it as many times as you want!