Phausto looked somewhat peeved. He peeked out from behind his canvas within a canvas and frowned.
"Hrrrmph. I haven't seen you or the lass recently."
Tamblin looked at the Portrait.
"I'm sorry Phausto. This year has been... difficult. Have you heard about the Chamber of Secrets?"
"Indeed I have. The Bread Baker on the third floor told me. He was always a gossip. I shouldn't have used so much orange in his pigmentation. Orange things talk too much."
"I'd like to get into the studio."
The Portrait was also a doorway from the Artiste's Alcove into a painting studio. Presumably the other three paintings in the Alcove also held rooms behind them dedicated to their artistic disciplines: poetry, dance, and music. The painting studio was the only one he and Cascata had figured out how to enter. The only other people who seemed to know the Alcove existed were a couple of older Gryffindor twins. He was pretty sure they hadn't managed to get into any of the adjoining room. Mostly they just stashed things in a corner of the alcove. Tamblin and Cascata left their stuff alone as the twins had quite a reputation around the school.
Phausto sighed.
"Very well."
The painting opened like a door. The room beyond was exactly the one in the painting itself minus the artist. The reverse side of the painting also showed Phausto; this time the background showed the Alcove. Tamblin moved to the back of the room where the Alchemirand stood. He and Cascata had discovered its use last year, with Phausto's help.
He poured the small amount of potion from his vial into the bowl of the Alchemirand. It began to shake slightly and the small portion expanded to fill the large bowl to the top. Tamblin rummaged through the cabinets until he found several clean jugs. He filled these from the Alchemirand. Once he had an ample supply he pressed the knob on the side of the bowl and the remaining potion seemed to evaporate. He took the jugs and stored all but one in the cabinets behind various painting supplies.
The final jug he took with him as he left. Back in his room he filled a large number of vials from the jug. These he tucked away for the moment.