Green’s Dictionary of Slang

1. a trowel.

1880		D.W. Barrett Life and Work among Navvies 41: Now then, my china-plate, out with your cherry-ripe, off with your steam-packet, and set your bark and growl agoin.
1927		Eve. Herald (Dublin) 30 Nov. 6/4: Cockney bricklayers seem to have a quaint language of their own [...] bark and howl — trowel.

2. a towel.

1981

P. Wright Cockney Dialect and Sl. 103: bark an’ growl ‘towel’.