Checking the temp of melted lead?


March 8, 2008, 06:50 AM
I started to melt my wheel weights into ingots yesterday. It very exciting to know I wont be paying the "Man" for bullets anymore. Would it be possible to check the hot lead with a Infrared Thermometer or should I use a regular one? Sears has a nice one.

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March 8, 2008, 07:12 AM
Here's a better solution I've been using for years:

This thermometer will stand up to the heat, the lead and getting banged around and dropped on a fairly regular basis. I've learned when it comes to casting, simple and cheaper is better, because anything that's complex is a distraction taking your focus away from the fact you're dealing with molten metal at over 625 degrees F.



March 8, 2008, 08:11 AM
Personal opinion, I'd go with the infrared. What could be simpler than point and shoot? We have one similar to that Sears one at work, and use it all the time on everything from roofs to bearings. I think it would be safer not to have to be sticking anything into the lead, or even getting your hand near the pot when you don't have to. For reference, year's ago as a construction pipefitter/plumber, I helped run probably miles of poured lead jointed pipe, so I have spent plenty of time around molten lead.
Oh, and I have cast a few bullets and sinkers too. I never used a thermometer for any of my molten lead activities either, come to think of it.

March 8, 2008, 09:01 AM
You might want to check this one out.

I don't own one but plan on buying one in the near future. Inexpensive and accurate enough for casting.

March 8, 2008, 09:08 AM
I have an infrared thermometer purchased from Granger it is quite accurate for many uses, but not so good on reflective surfaces. Polished stainless steel and dross free molten lead are two objects that I know cause it to give false readings. All is not lost though; the side of the melting pot just above the lead is pretty close in temp. FWIW I use a thermocouple and PID controller to maintain consistent lead temps.

March 8, 2008, 09:21 AM
The infra red will give surface temp just fine, but the regular old thermometer from Antimony Man that Dave linked to will give a much better idea of the leads working temperature.

Oh, and like jmorris said, infra red guns don't do well on reflective surfaces.

evan price
March 8, 2008, 09:35 AM
Personally when I was doing high temp work I used a J or K thermocouple and a FLuke meter.

March 8, 2008, 10:12 AM

March 8, 2008, 11:03 AM
"The infra red will give surface temp just fine"

And for a shiny surface like molten lead it will be wrong.
The emissivity of the material being measured needs to match the calibration of the IR thermometer.
Most are calibrated to a black surface, but you can calibrate them to a shiny surface using a thermocouple to measure the surface temp and then adjusting the IR to read the same temp.

For moderate temps we use a spot of flat black paint as the target.
For higher temps we adjust the IR using a thermocouple.

March 8, 2008, 08:36 PM
Having cast lead bullets since the late 1970's (I think it was 1977) I now use the infrared exclusively, but I don't make any adjustments suggested by brickeye, even though he's absolutely correct and credit goes to his knowledge.

I cast bullets the best in the low 600's, but anywhere from 580 to 675 degrees F is excellent. Most of the time it stays where I set the controls, usually about 625. At that range of temps, the infrared is certainly close enough without adjustments. I only check when I add more lead, to make sure the temperature gets up near 600 to begin pouring again.

The infrared is also HIGHLY useful for mold temp. I cast the best when the aluminum mold is in the low 500's, the cast iron mold in the mid 500's, and the brass mold (yes, I still have old brass molds!) just at 500. Once again there is a wide range where it works great, anywhere from 500 to 550 d F for all three.

At those ranges, the infrared is handy for both the pot and the mold and surely accurate enough. But you select the tools that work the best for you. It's your hobby, go have fun your own way.

March 8, 2008, 08:41 PM
By the way, my infrared was off only about 15 degrees due to the shiny surface. I tested it easily.

Find a piece of black steel or iron about two inches longer than pot depth. Put it in the pot. Let pot temperature stabilize a while. Pull out the steel and quickly shoot it with the infrared, and shoot the pot surface too. Compare the two.

March 8, 2008, 09:31 PM
I use an RCBS thermometer. But I've been thinking about making an electronic pyrometer from a gas water heater thermocouple.

March 8, 2008, 10:48 PM
Personally when I was doing high temp work I used a J or K thermocouple and a FLuke meter.

Getting all high tech with thermocouples.

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