How do you clean a mold?

[jpuke]

I've been casting with an RCBS mold for about 2 years now.  I have to cast hot to get good fills and every few casts I get a bit of a smear across the top of the mold which after time has built into a thin layer of lead near the edge of the mold blocks.  The bottom of the sprue plate stays clean, the only build-up is on the top of the blocks.  How can I get this off?  I've tried letting it sit with some Kroil on it, hoping that would loosen it up but it hasn't worked that well.  Any suggestions? 

[mechanic]

Propane torch.

[7 MM]

on the steel moulds heat it up with a hotplate or propane torch and use a brass bristle brush to brush it off.
It is not uncommon and all moulds eventually need cleaning.
You need to get it hot enough for the lead to liquify before brushing, then brush until there is no more lead.
Once it is clean checl how the sprue cutter works and if it seems loose tighten ever so slightly as too much is worse than not enough.
Hope this helps.

7 MM

[Cat Whisperer]

... and every few casts I get a bit of a smear across the top of the mold
... Any suggestions? 

Two; a) wait just a little longer to open the sprue cutter - let the alloy cool a few seconds longer (that will reduce the occurances); b) I mix a little titanium dioxide (molydenum dioxide also works) with a silicone grease and coat the sprue cutter and the top of the mould.  Lead pencil works for a period of time as well.  All keep anything from sticking.

[calvon]

Assuming that you are using wheel weights and that your lead pot is running at somewhere near 800 degrees Fahrenheit:

Pour the lead into the mold. Watch the sprue. At first it will be bright and shiny, indicating that it is still molten. Next it will freeze, and will take on a frosty look. Wait a bit longer and it will turn a dull gray. Then, and only then, open the mold and remove the bullet. You'll have a well filled out bullet and there will be no lead smear on top of the blocks or on the sprue cutter.

[Lloyd Smale]

i too use a torch. to prevent it you can try two things. First one is a lead pensil. Rub it all over the top of the mold and spruce plate before casting. Second is to get your mold up to casting temp and fill the cavitys. then open your spuce plate and leave the bullets in the mold. Take a qtip and put just a little auto transmition fluid on it and put a very small coat on the top of the mold and spruce plate. Make sure you get none in the cavitys and make sure you dont get carried away so it doesnt migrate into the cavitys. Repeat before every casting session. It also works good to lubricate pins on aluminum molds. Remember less is better. YOu want it thin enough that it about drys instantly. heres is a link to something that even works better. look for his spruce plate lube in the add. http://bullshop.gunloads.com/new%20bullshop__3_008.htm

[calvon]

Veral Smith sells mold lube that is a mixture of graphite and beeswax. It comes in little sticks maybe a quarter inch in diameter and three inches long. He recommends touching (barely) the lube stick to the alignment pins and the contact points on the top of the mold blocks and the sprue cutter. He suggests doing this to a hot mold just before you put it away at the end of a casting session. As others have said, a little is ok, and a little more is way too much. You don't want the lube to get into the cavities. I've used it for years with good success.

[Hank08]

I never, ever let any kind of lube get near my molds.  For cleaning the top of a mold, heat it til it melts and wipe it off with a dry cloth.
H08

[jpuke]

Thanks for the tips!