Really Dirty Lee Moulds

[mvozz]

I was picking up some lead (Linotype WW mix) from a guy that was getting out of casting. He had plenty of boolits and was old enough he decided to move on. While I was picking up the lead he offered me all kinds of stuff. I ended up with two Lee 6 cavity moulds. They looked pretty good the way he was holding them so I thought, "what the heck". When I got them home I swung the sprue plate over on one and was shocked to see how dirty the top of the mould was. The build up was so thick no amount of WD40 or other solvents would remove it. I ended up using a flat plate and some 400 grit sand paper to get it off. I polished it with 800 grit and hoped I didn't mess it up. The mould looks great now and is very smooth but the sprue plate was just as bad. I gave it the same sand/polish and it looks great and swings very smooth. I am pretty new to casting so I have to ask if this was the way to handle it? The other mould is dirty but not as bad. The buildup looks like baked on lubricant of some kind. There is a little in two of the cavities that won't budge with a toothpick but it doesn't look very thick so I will find out with a little casting if it will effect the boolets. So my question is do I give the other mould the same treatment?

[robert12345]

Nope, leave it alone.
The guy likely knew what he was doing.
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A dirty top on an aluminum mould is likely a buildup of bee wax, or other bullet lube.
That buildup, acts like a lube, to prevent the soft metal of the aluminum mould from galling.
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If you scrape the buildup off, you are likely spoiling a lot of hard work on the part of the previous owner, ...who wanted his moulds to cast good bullets.
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Dirty moulds work best,, er... aah... if they are dirty for a reason.

[GooseGestapo]

Indeed, you lubricate aluminum molds with Alox/beeswax bullet lube. I keep a dedicated tube of lube wrapped years ago in wax paper just for lubing the molds on my casting cart.

Rookie mistake. We all made them!!!
Also, heat the molds up and the lube will easily wipe off.

Also, don’t remove the blackening on the mold cavities. This is carbon from smoking the molds to get proper fill-out of the bullets.

BTW; Lee will void the warranty on the molds if you don’t lubricate them with Alox bullet lube.

What you do need to remove is any lead flashing or smears.

[bangerjim]

“For-geeeeeet-about-it”! Leave it alone. Try casting B4 you mess with anything else!!!!!!!!

I never worry about the gunk that builds up on the TOPS of molds. You need to be concerned when the carp builds up on the mold CAVITIES......that makes smaller and lighter boolits. And may lead to sticking slugs when you drop them during casting.

Most smoke their molds with candle/lighter/acetylene flames to form a thin carbon layer. No problem. They say it makes release easier. I am not one to argue with decades of experience. I smoke all my Al molds. ONCE! PERIOD!

I use 2 cycle motor oil (the blue stuff) for lubing mold sprues and joints. Beeswax (the old standby for generations) leaves brown garbage behind.

Banger

[buggybuilder]

I had a build-up on top of my Lee 6 cavity mold. Only live about half an hour from them....took my mold over to complain thinking I'd get a new mold. No Way! The man in charge said I had lead build up. He fixed it by taking a "NEW" razor blade and carefully scraped off the build-up and then polished it with 1000 grit paper. Works fine now. This is what he recommended for cleaning.

[mvozz]

I took some time to cast a few 45s today and they were great - even with my cleaning. The 38s were not so good, there is enough build up that it is leaving gift on the base of most of the boolits. Just a real thin ridge that I can scrape off with my fingernail. I have never had one do this but that is what I was afraid of with the 45 mould, the buildup was just very thick. This is an older style mould that doesn't have the vents machined on the top so it looks like I may have to give it the same cleaning to get rid of the slight excess sprue. It is thin but it is a pain to have to clean off.