[kragen]

polyurethane is a resin

tung oil is pretty toxic. boiled linseed oil has heavy metal salts in it to make it polymerize, though typically nowadays these are cobalt, iron, and manganese rather than lead; calcium and zinc are basically nontoxic alternatives

shellac is not water-soluble; it's alcohol-soluble and thermoplastic

the plantation sizes necessary to coat everyone's floor with tung oil or shellac are fairly modest

[e44858]

"Boiled" linseed oil is not actually boiled, to save costs they just add metal salts to catalyze the polymerization. You can get linseed oil without the heavy metals, that is actually boiled: https://www.triedandtruewoodfinish.com/products/danish-oil/

[kragen]

danish oil has heavy metal salts in it, specifically salts of cobalt and zirconium: https://www.coo-var.co.uk/files/ww/safety/308-Q271%20-%20DAN...

ionic cobalt and ionic zirconium are both of fairly moderate toxicity; they aren't in the same ballpark as things like lead and mercury, but they also aren't as relatively harmless as calcium or zinc

i think that normal 'boiled' linseed oil does have stand oil in it, as well as the siccatives we're talking about here and other additives like antiskinning agents

[e44858]

The one by Tried&True appears to be pure linseed oil: https://s3.gomedia.ws/wp-content/uploads/sites/11/2016/03/FB...