A lot of old world formulas are just too cool and sensible. Especially when tannins are in play. Aquafortis on curly maple to make the curls or tigering pop. Used frequently on early American rifles and tomahawk handles. Fuming white oak with ammonia for that rich brown tobacco color as commonly found in original arts and crafts style furniture. The whole piece of furniture must be cut from the same tree as the tannin content varies from tree to tree. If not you will get varying shades of color in your piece. Hard to find good veg tanned leather these days. Used to buy from a company in Washington state, but they closed like twenty years ago. I’ve yet to find any as nice as what they made. Not many tanneries left in the US. Who do you buy from? Anymore I typically use a Viking style boat wax with good results on my wood, iron and leather works. It’s a mix of raw linseed, beeswax and pine pitch. All three being anti fungal. North American Indian style brain tanned leather is probably the most comfortable leather to wear. Like silk, it is cool in the summer and warm in the winter. Nice and supple. Fun to work with. Once smoked, very anti fungal. Chrome tanned buckskins suck to wear. Good for chaps, aprons, gloves and the like, but not for garments. Just can’t beat brain tan for wearing. And the great part, every animal has just enough brains to tan it’s own hide.