Wiktionary
vb. To finish (painting of a wall etc.) by rolling a rag over a coat of paint or glaze.
Usage examples of "rag off".
The clerk raised his hand and pushed the rag off his forehead and onto the pillow, and then let his arm fall back to his side.
He pulled the rag off his head and ruffled, his short hair, making it stand up in tufts.
I almost ignored it, eager to try the next door along the corridor, but then I ventured inside and, with the same hand that held the gun, I plucked the rag off the floor.
Sharpe, taking the rag off his rifle-lock, had to shout over the noise of wind and surf.
You don't have time for a real change, darling, but do get that rag off!
He took the rag off the lock of his rifle that had protected it from the dew and tested the tension of the spring with his thumb.