Mold break-in time?

[Nocturnal Stumblebutt]

I have noticed that Lee molds start producing their best boolits during or after their 3rd casting session. I have read that others have experienced this. My question is whether iron molds have a similar break in. Thanks

[chsparkman]

I never noticed that with my RCBS, Lyman and Saeco molds. They seemed to work great right out of the box, provided the oil was cleaned off.

[**oneshot**]

I took other members advice and I put my molds through a heat up/cool down process. After cleaning I preheat the new mold, then pour 15-20, then set the mold off to cool down. total of 3 times. I do this while casting another mold, 1st at the beginning, 2nd in the middle(adding alloy to the pot) and last at the end. It has worked well with the last 4 molds I've bought.
I guess it's the same as casting 3 times, and once I start to cast it starts with great boolits after just a few pours and is also when I start to figure the way that mold likes to be cast.

[454PB]

As long as they are thoroughly degreased first, every brand of mould I own works well after about 5 cycles.

I think that "break in" theory started many years ago when Lyman recommended casting to burn off the rust preservative they used.

[runfiverun]

most aluminum and brass molds really need a break in of some heat cycles.
this gives them an oxidization in the cavity's. [patina in a brass mold]
and really helps get the cutting oils out of aluminum molds.
i like to cycle my mehanite molds too.
once you see them go from white to gold to blue after a couple of cycles go head and do a big run of boolits.

[GP100man]

Yep , couple or 4 cycles here on aluminum molds , steel 1s a qwik cycle to frosty boolits then a kool down seems to work for me .

It seems the more porous a material it is the more cycles & heat it takes to draw all the oils from the pores.

[MtGun44]

My first thought is you are not cleaning them well enough. Scrub a new Lee mold with Comet
and a toothbrush first thing. Dry and inspect for burrs (scrubbing with Comet will remove smaller
ones) and remove - hard wood scraper works sometimes, sometimes careful work under
bright light and magnification with an exacto knife will remove burrs.

My experience is that my Lee molds (and others) work fine as they come up to temp in first
casting session.

Bill