My alloy was glowing.

[mto7464]

Turned on the Lee pot and went back inside the house, got sidetracked and came out 30 plus minutes later. The alloy was glowing faintly in the darkness of my shed. I drop two one pound ingots in it and they melted right now. What do you suppose it got up to temp wise? Any ill effects to the alloy.

[454PB]

I'm surprised the thermostat let it get that hot. It wouldn't hurt the alloy, the temperature dropped like a rock when the lead started melting.

[KYCaster]

In total darkness, you'll see some color slightly below 1000*. More like 1050-1100 in shade or subdued light.

Jerry

[uscra112]

Actually you can know with a fair degree of accuracy.

If you just barely see it as a dark red color, (and it has to be in the dark to see it), it's about 750 degrees F.

Turns out all substances glow at the same color for a given temperature. Doesn't matter whether it lead, iron, or carbon. The old-time blacksmiths could judge the temperature of their metal solely by eye, even thought they had no thermometers to tell them what it was in degrees. They had quite a few words for the various colors, too.

A little web searching turns up the following table:

http://www.sizes.com/materls/colors_of_heated_metals.htm

[Bret4207]

Consider yourself lucky. Most times when I walked away from my Lee pot I returned to find the pots contents dribbled all over the bench top. Hence, no more bottom feeding pots for me. YMMV.

[Freightman]

I left mine and was sure glad I have it sitting on a metal desk, what a mess. I threaded a screw in the nipple took out the valve handle and rod and laddle pour now. The color is normal as has been said. When I worked at a zink smelter we saw a color difference when we drew the zink off the furnace and you could see it change as it hardned into plates.

[Dale53]

It is not a really good idea to leave a lead pot unattended. Do I EVER leave mine unattended? Yes, but that still does not make it a good idea.[smilie=1:

So, I kind of compromise. I don't leave it unattended for long...

Just a bit of "food for thought".


Dale53

[lurch]

Another suggestion: Use a thermometer. The Lee pot does not directly sense the melt temperature to cycle the power on & off to the heating element. Use the thermometer to get a handle on where the temperature will stabilize for any given knob setting. When you do this, be sure and let the melt come to a stable temperature. It will wander around for a while.

There are a couple of other factors that will come into play with the Lee pots that you should also be aware of:

1. The "stable" temperature will be different denpending on how much metal is in the pot. More metal in the pot will result in a cooler stable temperature. I can't say for absolute certain why this is but I can hazard a fairly educated guess. Since the themostat is at the top of the column behind the pot, it relies significantly (Not totally since some heat will come from where the heating element secures to the tower. I don't know how much of the ends of the heating element are not active, but I would guess 1 to 2 inches. There will be some heat conduction through this path, but what the weighting is relative to the radiant heating I can't say.) on radiant heat from the pot to heat the tower. A higher level of molten lead in the pot makes more of the upper portion of the pot hotter, therby heating the column more, Hence a lower melt temperature for a given thermostat setting.... I think.

2. To a lesser extent, ambient temperature. Hotter ambient will lower the melt temperature since the column does not have to heat up as much from the pot heat transfer to trip the thermostat. Since ambient temperature usually doesn't vary that much (or it could depending on where you cast) the effect should be less pronounced than 1.

I would say convert it to PID control but I've beaten that horse enough elsewhere.