heat cycle for new mold

[porthos]

what is the process; and, why??

[Mk42gunner]

Basically you heat the mold to around 350-400 degrees Fahrenheit and let it cool naturally three or four times. This helps to build a patina on brass or aluminum molds so the lead releases easier.

Its not totally needed on an aluminum mold, but my Lee 312-185 suddenly started dropping boolits a lot easier after the third or fourth time I used it, so there may be something to it.

I've never bothered doing it to an iron mold.

Robert

[gwpercle]

It "Seasons" the mould just like you season a black cast iron frying pan .
Another thing it does is the heating drives out CNC machining oils that are forced into the pores of the mould block out . Clean the cutting oil out of the cavities after each heat cycle .
You do this because oil will cause wrinkles on your cast boolits and the wrinkles will continue untill all the cutting oils have been heated out and cleaned off .

In the old days we spent hours casting wrinkled boolits , remelting them and casting untill all the oils were burned off ... lots of work for nothing ...heat cycling & cleaning is just an easier way to condition a new mould . Acetone is a great de-oiler .
Gary

[USSR]

It's basically a brass mold thing. What you do is heat a new brass mold up (after first removing any oil from it) to about 400 degrees, then allow it to cool down before doing this procedure a couple of more times. What it does, or supposedly does, is put a patina on the brass which helps in casting good bullets right off the bat. I do it with all my new brass molds. Whether it is necessary or not, who knows.

Don

[rintinglen]

I have brass molds from Accurate, MP and NOE and I have found heat treating does cut down on the time required to get good boolits from the first casting session. (As well as thereafter, I suppose.) I boil my new mold in distilled water with a few drops of dish washing fluid, being sure to completely immerse the mold in the solution and keeping it submerged until it has been boiled for about 15 minutes. (The iron sprue plate will rust at the water line if not completely covered.) I warm the oven to 400 degrees while the mold is boiling then when done boiling, I immediately take the molds halves and shake them firmly to remove any water droplets and then put them in the hot oven for 30 minutes on an old cookie sheet. When the 30 minutes are up, I remove the cookie sheet and let the mold cool until it is warm to the touch, but not hot, then I put the mold back in the oven for another half hour, repeat the cooling process and then heat the mold for a third time, then let it cool. All told, this takes the the biggest part of an afternoon--3+ hours. But then bullets drop out of the mold with ease once the mold is up to temp.

[justindad]

What are the wrong ways to heat a mold, that someone might reasonably do?

[USSR]

What are the wrong ways to heat a mold, that someone might reasonably do?

Heat it at too high a temp. Keep your oven temp at 400 degrees or less and you will be fine.

Don

[Mk42gunner]

What are the wrong ways to heat a mold, that someone might reasonably do?

Torch of any sort.

As USSR said, stick with the oven.

Robert

[gwpercle]

I'm Old School , pre-heat the mould by sitting blocks on the edge of electric pot ...
Cast boolits untill they start dropping frosty and I get tired ... set the filled mould on the pot rim , shut off power to pot and let everything slowly cool down ... Repeat the next day , three cycles usually do it for an aluminum mould .
Gary