If we're getting to the point that we can commonly slather giant gronti in the stuff then we're at mass production time, otherwise not really.
This measure is actually pretty easy to achieve.
As it stands, it only takes six Smelters to make enough Adamant to armor a dwarf in it every turn. Could we ever armor every single dwarf in Kraka Drakk? Nah, that wouldn't be happening.
However its only two turns at that rate of production required to make the amount of Adamant necessary to make an Adamant suit of armor/skin for an Ogre sized Gronti. 18 bars to make it out of Adamant entirely if I remember what soul has said correctly.
Also IIRC soulcake said it was 32 bars to make a Bloodthirster sized gronti out of Adamant. If you use the math for the Ogre sized one that comes out to needing between 10 and 12 bars, either way at 3 bars a turn that would take four turns of waiting. 4 bars a turn, eight smelters, would be 3 turns, 5 bars a turn would 2 turns etc.
Ten smelters is a lot I'll grant you that but what I'm getting at is more highlighting a point I raised a while back that even singular bars per turn increases are Very Significant in terms of what it lets us
do. Its not particularly difficult, mostly just time consuming, to get to the point where we're making what I expect would be more than Snorri will most often use in a turn and will be encouraged to stockpile the rest for bigger projects. This point is getting to 4 bars a turn, since we can spend between 1 and 3 bars every turn on projects and save 1 since we won't often have projects that call for more than 3 bars all at once. Our project timescale for stuff shortens nicely with this.
We have in our hands the means to basically be able to make most of our dwarf-scale creations, our most common scale of creations, out of Adamant if we spend any significant effort in that direction. I don't however consider this mass production or production of scale, because its still fundamentally just Snorri and his closest compatriots in his apprentices benefiting as artisans because they can make dwarf scale creations out of it whenever they want but large scale creations take a large amount of time.
To wrap it back around to the mass production argument, personally on my end it wouldn't make any sense for it to happen. There's cultural pressures and impetus not to and I have no inclination to make it happen because it countermands the point of playing within the limits of a Runelord as a character. Thankfully, referring at the above, I don't think its going to happen because of smelters Snorri personally builds.
At the moment 65 bars every fifty years is the current max output of the entire Karaz Ankor counting us and the Brotherhood. As Bogrin laid out, about a dozen every decade, which means that Snorri is responsible for one twelfth of the entire Karaz Ankor's adamant production in its current artisnal scale. Like, that sounds significant, but then consider the scale it operates on and its in the grand scheme of things not that comparable to the ideas of mass production.
Looking at the above if every member of the brotherhood made one Smelter, together we'd all produce 71 bars a turn (Soul's outlined they have 70 members), one for each of them every turn and one for us. This is a qualitative improvement on a huge scale, even before we get into the five turn total. That five turn total would be 355 bars a decade. However there are a couple of things which interact with this hypothetical to discourage it:
The training time required to teach everyone in the Brotherhood the Master Rune of Purification. This is going to impose a hierarchy of prioritization, probably relatively similar to the hierarchy of seniority present in the brotherhood because that's how Dwarves generally work. Old folks get the best stuff because they're skilled enough to make best use of it, in their minds.
The time to make 70 smelters. This has multiple factors, one of them connecting to a later point about the plausible rarity of voidstone, but also has to do with the time it may take to hunt down more voidstone. This is going to reinforce the idea that those who go out to look around, i.e those with the time to do that instead of other things, are going to find it and build theirs first once they learn how.
Both of these time factors of the problem will slow the hypothetical down, as will any other ones that I may not have thought of.
Another important factor is the amount of voidstone on the planet may not support every member getting one. To connect to the above point about making smelters, it might be possible to find or create that much over an extended period of time, but Snorri found one tenth of the required amount on a lucky roll. But its limited supply is still a significant crimp on actually making this much, even if I think its a resolvable one.
A factor that I think is the most significant is that once knowledge of the Master Rune and smelting array is disseminated Snorri's fellows are going to have interest in adapting the Master Rune into their own specialties. Engineering Runes, Banner Runes, Armor and Weapon Runes. Every piece of voidstone put into an adapted Master Rune of Purification or a talisman using the original rune that isn't a Smelter, is one that won't go into making a Smelter and there is nothing really to be done to resolve that competition other than finding an alternate material. Every Runelord and Runesmith that wants to make something else than a Smelter with voidstone will consume voidstone that could have become a Smelter. So, there's going to be a sharp limit on the number of Smelters produced during the scope of the Golden Age and this quest, since those are synonymous.
And for as much as 355 bars every half century is, I don't think it really meets my measure of mass production because it is fundamentally one bar per runesmith per decade. If they pooled their resources they could do amazing things with it, but they'd be one offs because of who they are. My own measure of mass production would be something closer to what small scale mass production means IRL, and involves stuff like being able to make enough Adamant to armor a thousand dwarves every decade, if you had the workyears to do it. (Not workhours) Which if 71 individuals are responsible for it you
wouldn't.
Furthermore to make 3000 bars of adamant every decade, and thus make enough for 1000 suits of armor every decade, 6000 Smelters would need to be made. That would require that the 71 dwarves of the brotherhood, and us, make 85 Smelters
each.
It's mindboggling how much voidstone you would need. Put that together with what I lay out above, and most of the caution that I think needs to happen with Adamant production that applies to things in scope of this quest is getting to the point Snorri can put out a suit of armor for a dwarf every turn and still stockpile some. And that's because of how it would obviously change our behavior because of the project timescale we move to at that point.