Metal Casting Zone

I am casting 2# weights from a 5# lead scuba weight. The mold is a 2# aluminum mold for a weight belt. I am melting the lead in a cast iron pot using a propane torch. Skimming off any impurities and pouring when fully melted. I was able to get one good weight out (first one). After that they are all cracking apart when I try to get them out of the mold.

I have made a lot of fishing lures in the past, but this is the first time to pour large amounts of lead at one time.

Open to and and all suggestions why these are not turning out. Lead too hot, mold too hot, not hot enough,...???

Richd, first of all welcome to the forum.

I used to cast a lot of Scuba weights and I only had trouble with the first one, then I started heating the mold over the lead while it melted. Do you know if the weights you are using is pure lead or an alloy. Old used up printers lead will get brittle after some of the alloys are used up like the Tin or Antimony. I think it's the Antimony.
Printers lead melts at about 560 F where pure lead is around 660 F. Try some tire weights and see if they work better, but don't mix it with your lead at first.
Where do you dive? I used to get wet a few years ago...OK about 20 years ago. I was an Ohio mud diver, and I've been to the Keys and Puget Sound.

Thanks for the suggestion. It may be that the mold is too cool when I pour. That is a great suggestion. I used a 5# weight for the first one and then I added some lead shot in for a second and third pours. I do have a bunch of dental lead (from X-Rays) that I can give a try as well.

I live in WI. Just started getting into wreck diving.

I checked out your Scuba Forum. Looks like the Green Bay area, BRRRR.
I had a drysuit the last couple years I was diving. I loved it. It takes some getting used to.

I know what you mean about the dry suit. I only have 4 dives on mine and just starting to get comfortable with it. That is the reason I need to make some lead weights. I only need about 4 - 6# of ballast to descend and all my weights I was given were 5 and 6#. Wife doesn't really need any weight but when she has a dry wetsuit (seems strange to say that but you know that I mean...) She needs a couple pounds of ballast as well. Just did a lake dive with a fellow dive club member. Stayed right around the first thermocline so it was a nice dive in 60 degree water. The nice wrecks are in Lake MI and most sit in 80+ feet so those are about 38 degree dives - definitely dry suit dives.

Hoping to get to my lead molding today. I will be seeing the guy that lent me his pots later this week and would like to get them back to him right away. Nice when we can share equipment so it isn't too expensive to make the weights.

Is there anything to do to help the casting release from the mold? Seems like I have to let it cool for a while or the lead is not firmed up yet. Maybe I am letting it set too long or maybe I need to let it set longer...not sure but I have to really give them a good bunch of whacks to get them out.

Blacken the mold over a candle, or rub a little graphite in it if you have some.

Thanks for the suggestion. I will give it a try tomorrow.