Apparatus for applying liquid to a running yarn (12) in a textile machine comprises a hollow body (28) providing a manifold (20) for the liquid and an elongate tube (33) extending horizontally across the manifold (20). The tube (33) is retained to a bore (32) in the body (28) by a yarn guide (29) which is detachably secured to the body (28) and the bore in tube (33) communicates with a groove yarn path (38) provided by the yarn guide (29) via a bore (31) in the yarn guide (29) of larger diameter than the bore in the tube (33). The constant supply of liquid to the yarn (12) is provided by the controlled flow of liquid along the tube (33) whose length is at least 100 times the diameter of the bore therein. A height adjustable weir (17) in a liquid supply tank (16) supplies liquid to the manifold (20) at a predetermined pressure. The yarn path (38) has a plurality of yarn contact points (39,40) to ensure complete application of liquid by the yarn (12).