This furnace is worthless

 
 I stirred them up, and as expected, the dwarves got angry and gathered around me. I somehow had the feeling that if I said something negative about their work, this would happen.
 Sten’s story was also a trigger. Dwarves are proud of their work, and at the same time, are also absolutely confident. That’s why the previous generation was so stubborn and challenged the magic architect founders to a competition.
 This time it wasn’t a contest, but it was necessary to pique their interest, so this was a good move, even if they didn’t have a good impression of me.
 
 ”Something like a human has the nerve to act so conceited.”
 ”I’ll beat you up so you can’t speak like that again!”
 ”Wa-, wait, everyone. Calm down for a bit!” (Eph)
 ”Na~ah. No matter how much missy asks, I just can’t do that.”
 ”He’s making fun of the work I’m desperately doing the work boss here.”
 ”But, what’s the point if the way you’re doing it is wrong?” (Wirk)
 ”Then show what it is you’re saying we’re doing wrong!”
 ””””””Yeah, yeah!””””””
 
 Alright, things are so far going the way I expected.
 
 ”Then let’s take a good look at the furnace first.” (Wirk)
 ”What?”
 
 I was curious as to what kind of environment the dwarves were striking iron in. So I asked, but the dwarves showed a puzzled reaction.
 
 ”You say you want us to show a human the heart of our work!”
 ”I’d better start there, or we won’t be able to talk. There’s a high chance there’s something odd with the heart you guys are so proud of.” (Wirk)
 
 As I answered so, the dwarf I was talking to gritted his teeth and was looking my way as though he’d swing the hammer in his hand at me any second now.
 
 ”Are a dwarf’s hands and those hammers meant for hitting people?” (Wirk)
 ”Wha-, what did you say!”
 ”I would hate to think that a proud dwarf would immediately resort to violence.” (Wirk)
 
 Those words I uttered were both a warning and a provocation. I carefully watched to see how he would react after I said this. My friends are ready to respond in whatever way.
 
 ”…tsk, if a human goes so far as to say that, I can’t beat you up. Fine, I don’t got the boss’s permission, but… I’ll show you the one I’m responsible for. Come!”
 
 I followed the dwarf I’d been dealing with. It wasn’t that far from where we were, but he wanted me to see it properly right before me.
 
 ”Take a look, this furnace is our pride and joy!”
 ”… this is?” (Wirk)
 
 It was a strange furnace, as if it had been hollowed out of the wall. I looked inside — and to my surprise, it was filled with lava. The fire that could be seen was from the lava.
 
 ”So you’re using lava?” (Wirk)
 ”Yep! Our prided furnace uses the natural lava that is the blessing of the mountain gods!”
 
 I see. I get it now. No wonder they mass-produce such half-baked products.
 
 ”Mu, is this a furnace? It kind of looks hot from a glance.” (Bamboo Princess)
 ”At least in appearance.” (probably Wirk?)
 
 The Bamboo Princess also peeked in, sweat pouring down her forehead. Certainly, just the impact of the appearance is amazing.
 Seeing mine and the Bamboo Princess’s exchange, the dwarf’s face scrunched up. He couldn’t stomach me saying that it was only in appearance.
 
 ”Say, have the dwarves been continuously blacksmithing with these kind of things?” (Wirk)
 ”At least, as far as I’m aware.” (Eph)
 
 Eph nodded. On the other hand, the dwarf’s expression looked grim.
 
 ”I’ve heard you for a while now! Do you have a problem with this furnace!”
 ”That’s right. As I said before, the stuff you guys make is half-hearted, but now I know the reason why. This furnace is worthless, it’s not something you can praise.” (Wirk)
 ”Bastard, wha-, what the hell did you say!”
 ”What the hell are you doing!” (Jay)
 
 Just as he turned to me and came at me with heavy yet rushing steps, Jay appeared.
 
 ”Bastard, I said get out of this city right now!” (Jay)
 
 — and then he shouted at me.
 
 ”We came here because we wanted to talk to Papa!” (Eph)
 
 Eph talked back with a strong tone. The glaring between father and daughter continued for some time.
 
 ”I ain’t got nothing to say to you!” (Jay)
 
 Jay broke the silence, and continued talking.
 
 ”To begin with, what are you doing looking at our furnaces of your own accord! Why’re you letting a human, and a magic architect to boot, doing as he wants, however he pleases!” (Jay)
 
 When Jay glared at them, the dwarves stopped moving.
 But Eph didn’t stop.
 
 ”That doesn’t matter! Wirk wanted to see the furnace to tell you that the way you’re doing ti is wrong!” (Eph)
 ”What did you say? That my way is wrong!” (Jay)
 
 Jay looked at me, his shoulders shaking at Eph’s comment. The dwarf, who had been silent, then opened his mouth and turned to Jay.
 
 ”Th-, this human said that the stuff we made is half-hearted… and that this furnace is worthless.”
 ”Worthless? You bastard didn’t seriously say that!” (Jay)
 
 Jay questioned me threateningly. But now I’ve got him more or less curious about it. So it’s now or never to talk.
 
 ”That’s exactly so. This furnace is worthless, ya know. I’ll come tomorrow. I’ll show you a real furnace then.” (Wirk)

 [TL: For anyone curious, I’ve been somewhat interested in stuff like this before, and there’s a few problems I can pick up on with using lava like this as a furnace. Firstly, hotter isn’t always better. You normally want to make use of various temperatures for various periods of time, in order to get different qualities from your metal. Secondly, assuming the lava is also being used to smelt their ores: they are probably using pure iron. This might sound great, except, well, it isn’t. When you smelt iron using coal, if done correctly, you’ll end up with steel. As everyone can guess, steel is better for making equipment than iron would be. By smelting their ore in lava, I’m surprised they even get their iron back without adding more bloom to it (bloom is basically the part of the ore that isn’t iron. Well, don’t quote me on this. It’s just my half-assed knowledge on the matter.]