Wool grease is the unprocessed form of lanolin drawn from the wool scouring process. Lanolin is a fantastic natural lubricant, waterproofing compound and sealer for the likes of leather.
Why is it called 'Essence of Romney'? Simple. This raw and unprocessed product smells just like your uncle's woolshed. Each container comes with my personal guarantee; when melted/softened in any domestic kitchen it WILL offend the nostrils of every wife, girlfriend or significant other. I kid thee not however the benefits far outweigh the matrimonial disharmony.
'Essence of Romney' is a particularly useful product for treating fibre shotgun wads in order to achieve an effective gas seal whether loaded in cartridges or muzzleloading shotguns. Dry fibre wads do not fully contain the super heated propellant gases and lead to clumping of shot whereas wads treated with 'ES' seal the bore as bullet lube does on cast bullets to protect the shot payload and produce premium patterns. Wads can be rolled in melted 'ES' to treat the circumference only or saturated fully. 'ES' can also be used in lubricating compounds.
Above left, 12g pattern shot with dry fibre wads, above right, 12g pattern with 'ES' treated fibre wads.