They dont advise using wound sealents now days, if you have given it a clean cut close to the trunk without leaving a snag then it will heal its self given time, at one time you could buy a wound sealent called arbrex which was like bitumen, julien.

you could use grease or emulsion to do it.

We use a water-based asphalt emulsion here in the desert to stop our ubiquitous borers, but if that is not a problem in your area, it is better not to. Some trees are subject to fungal and bacterial diseases that can enter through fresh wounds, in which case a copper based fungicide, such as Bordeaux mix or copper soap, is useful.