iris_jones89•11d agoProlific Poster

Found a chart of old forge temps online from the 1800s... blew my mind

I was looking up something about welding heat and stumbled across this scanned blacksmith manual from like 1887. It had a color chart for steel temps based on the shade of red you see in the fire. Turns out those old timers could nail the right heat within like 20 degrees just by looking. I've been using a digital thermometer for 5 years and still miss sometimes. Has anyone else tried learning to judge heat by eye instead of just relying on a gauge?

2 comments

2 Comments

hugo_craig11d ago

Man oh man that color chart stuff is no joke. My granddad was a farrier and he never owned a thermometer in his life. He'd just look at the steel and go "needs another shade darker" and that was that. The scary part is how they worked in coal forges where the light messes with your eyes. I tried it once with just my shop lights off and a small fire. Took me forever to even see the difference between cherry and orange let alone the half shades they talk about. The real trick nobody brings up is that your eyes adjust to the heat glow after like 20 minutes in the dark. Trained them old timers probably had that built in after years of not running inside for a digital readout every five seconds.

cole_patel4111d ago

The part that always blows my mind is how they managed it without burning daylight. You got a limited window with a coal fire before it dies down, and you're supposed to just stare at a piece of metal and trust your gut. Meanwhile, I've got a digital pyrometer that beeps at me and I still overheat half my stock. Those old timers developed a kind of sixth sense from pure repetition, but what nobody says is that they probably learned by messing up a lot too. There's no way your granddad got it right every single time as a kid. He just had nobody videotaping his mistakes for the internet to see.