ideal lead temp for casting 8BHN lead?

[SaltyJim]

Is there an ideal temp for casting 8BHN lead boolits, RBs, minies, Maxies?
I'm getting wrinkles. I've cleaned the mold cavities. I've tried temps from 650 to 850.

Thanks.

[contender1]

It sounds as if you MIGHT be having issues due to a cold mold. The mold needs to be up to temperature as well. And if you allow it to cool too much between pours,, it can do the same thing. Especially with aluminum molds.

[Ed_Shot]

My first guess is that your wrinkles are due to your mold being too cold. Are you pre-heating your molds on a hot plate? Don't know if your molds are aluminum or iron but I can't believe an alloy temp @ 720 degrees wouldn't do the trick. Also, do you know the tin content of your alloy.

[lightman]

I have the PID that controls my casting pot set at 720º. This works well for any alloy that I cast with and both steel and aluminum molds.

[405grain]

When you're casting with straight lead for black powder bullets you will sometimes get wrinkles. Having the molds up to temperature can help, but adding even the smallest amount of tin will allow for better mold fill out. You don't need to add enough tin to change the material hardness of the bullet, just enough to give the alloy better flow and fill out. I used to cast for 58 caliber Minies and even when I did get some small wrinkles they still shot fine.

[JonB_in_Glencoe]

Wrinkles are all about mold temp, you want to get the mold hotter.
Cast faster to get mold hotter.
Also if you are casting in windy conditions or breeze or running a fan ...that can cool your mold.
Shield the area were your mold is.

[cwlongshot]

I run my main pot which mostly uses COWW hardness lead @ 7-725°. Works well for me.

My dead soft Pot I like hotter 750-775°

Of coarse it changes with mold sizes, number of cavity's and alloy. But generally I ise above.
CW

[kevin c]

Other thoughts on casting “hotter”:

Preheat the mold on the lip of the pot, by holding a corner in the melt, or by carefully heating it on a hot plate. This saves cycling the mold several times to warm it up.

Pour a more generous sprue that will conduct more heat through the sprue plate.

Shorten the time between cycles, but give the sprue a bit more time before cutting and dumping.

Don’t be too stingy with the flow of alloy through the valve: a thin stream cools faster as it drops and takes longer to fill the cavity. Slow filling may allow alloy to freeze too fast.

Minimize the drop distance from valve opening to the sprue plate opening.

Set up a wind break if casting outside in cooler weather, especially in windy conditions, to slow both alloy stream and mold cooling.

Remember that, even preheated, adding ingots will drop the melt temp significantly, which means the pour will freeze up faster in the same temperature mold.

Wrinkles seem show up with the least bit of oil anywhere near the mold cavities. This is not just the oils that may remain on the mold from machining or from storage, but also goes for the sprue plate lubes applied before and during a casting session. Even leaving bullets in the cavities when applying lube just on top of the sprue plate, let alone the underside or the mold block tops, I can expect wrinkles for at least a couple pours.

That’s all I can think of right now.

[Martin Luber]

Oil contaminated moulds will do that. Clean well to be sure

[BJung]

The ideal temperature for a lead alloy is when the temperature is low enough to allow the lead to start to solidify plus 100 degrees. To me, it's around 720 or so where the lead doesn't flow clumpy on the cool end and like water on the high end.

[fredj338]

I have the PID that controls my casting pot set at 720º. This works well for any alloy that I cast with and both steel and aluminum molds.

THis is just about where I am at for any alloy. Preheat the mold, makes all the diff.

[HARRYMPOPE]

When you're casting with straight lead for black powder bullets you will sometimes get wrinkles. Having the molds up to temperature can help, but adding even the smallest amount of tin will allow for better mold fill out. You don't need to add enough tin to change the material hardness of the bullet, just enough to give the alloy better flow and fill out. I used to cast for 58 caliber Minies and even when I did get some small wrinkles they still shot fine.

my experience 100%

[Bigslug]

I typically run the pot between 750-785F, and work to get the mold up to a temperature where it takes the sprue maybe 10-20 seconds to finish its color change from liquid to frozen. If a mold isn't behaving after a warm up on a hot plate, I'll dunk the far corner in the pot for a ten count. That will usually give a pour or two where the sprue takes a little longer than desired to harden, and then things settle down into equilibrium with proper casting pace.

And new molds often just need breaking in to burn out any remaining cutting fluids, storage oils, etc... I've never found carb/choke/brake cleaner to do the job 100%. Sometimes you just have to run dud bullets for 20-30 minutes to purge it.

Expect a few dud pours after you add sprue plate lube as well. I do this carefully by wiping a little on, then wiping off as much as I can with my "Ove Glove", but I still expect the mold to have a case of "the vapors" for several pours.

And as others have said, sometimes an ounce or three of tin is needed to reduce the lead's surface tension to allow good fillout.

[oley55]

I typically run the pot between 750-785F, and work to get the mold up to a temperature where it takes the sprue maybe 10-20 seconds to finish its color change from liquid to frozen. If a mold isn't behaving after a warm up on a hot plate, I'll dunk the far corner in the pot for a ten count. That will usually give a pour or two where the sprue takes a little longer than desired to harden, and then things settle down into equilibrium with proper casting pace.

And new molds often just need breaking in to burn out any remaining cutting fluids, storage oils, etc... I've never found carb/choke/brake cleaner to do the job 100%. Sometimes you just have to run dud bullets for 20-30 minutes to purge it.

Expect a few dud pours after you add sprue plate lube as well. I do this carefully by wiping a little on, then wiping off as much as I can with my "Ove Glove", but I still expect the mold to have a case of "the vapors" for several pours.

And as others have said, sometimes an ounce or three of tin is needed to reduce the lead's surface tension to allow good fillout.

Good post and real life experience right there, I especially like the "vapors" part. Always wondered why after being way too careful somehow some contaminants still get into the cavity/s. The presence of oil/lube vapors may very well be the issue.