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I recently acquired a MP 2 cavity brass mold 477-460 with pins from White Eagle and would like to shorten my learning curve/prep time when I cast with it for the first time. I've read brass molds can be finicky in finding the right temp. The ambient temp in my basement right now is 58 degrees on a cheap mercury thermometer and the infrared gun I have says 60.4 degrees pretty consistently on the mold. Does anyone on here have a "target" temp for one of these brass molds I could shoot for?
I don't know for sure about the mold temperature but I have to run my mix hotter with the MP brass HP molds than any other. I usually try to cast with my mix around 750 degrees but the MP molds require somewhere in the 850 degree range. Maybe this will help.
Good Luck,
Rick
I don't measure mine. I start with it on a hot plate that i guess is somewhere around 400°, so lead will not stick to the outside of the mold if I dip an corner in the pot. I have a PID and run the pot at 750° and cast fast (cut sprue as soon as solid) until the boolits begin to frost. Then slow down (sprue count 8 to 10). The cavit count and size will determine how long that takes. Little .172 are the hardest to keep the mould hot and goes back on the hot plate every 5 to 6 fills.
I judge mold temp by the time it takes the sprue to freeze and the "look" of the cast boolits. My "target" is a uniform dull grey boolit, not totally shiny, not partially shiny, and not overly frosty.
Now, there is always a exception, I have one mold, that needs to be run hotter than typical, and those boolits need to look frosty and maybe even considered overly frosty...The mold has it's reasons, I don't question them.
The Infrared thermometers don't read metal well but you can put a spot to read on the mold with Birchwood Casey Brass Black.
I have a hotplate with 1/4" steel plate on top and a sheet metal open front cover, a mold garage. The mold gets parked there if there is a pause in casting, it takes the pressure off. I have the hotplate set about halfway and found the right temperature by trial.
I agree it’s about sprue cool time, but if you want to make your laser gun work on it I find that spraying it with Frankford graphite mold spray makes it read well. Black paint would suffice as well.
60.4°? If your mold is room temp then yeah, that’s not warm enough lol. Try about 375° higher.
Just kidding of course. If you’re saying a hot shiny brass mold is reading 60.4F then that’s because they don’t work on metal, the beam bounces off or something. Readings can’t be used at all unless you blacken the surface
Thanks for all the good advice! I painted a black spot the size of a dime with a black marker on the outside of the mold then took readings with the IR gun. The mercury thermometer read 59 degrees today and the IR gun read 61.0 degrees every time I took a reading. If the ink spot doesn't burn off I may be good to go. If it does burn off I'll preheat it on my hot plate with an old circular saw blade and run the pot hotter than usual.