[knodi123]

sure, notice how he says things like "3 double handfuls of charcoal, 3 single handfuls of iron-bearing sand", or "dry fire for one hour before trying to smelt", etc. Any time he mentions a number or a ratio, I guarantee it's hard-won knowledge that took ages to come up with (even if it was one of his ancestors that did it, and he just learned it from a book).

[ithkuil]

And/or a combination of "it worked with 3 handful; I'll note it down and not mess with it"