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Thread: cleaning aluminum bullet mold with electrolysis

  1. #21
    Boolit Master
    Dragonheart's Avatar
    Join Date
    Jan 2012
    Katy, Texas
    Quote Originally Posted by Joe S View Post
    Thanks Dragonheart, peroxide and vinegar is something I have not yet tried. To address some of the comments made above, I normally cast at 850 degrees, which is where I usually get consistently good bullets. I normally cast with 30-1 but tried 25-1 and 20-1 with no improvement.
    Also tried casting a around 700 degrees with no luck.
    I assume that hydrogen peroxide which is commonly available is what you are recommending, am I correct?
    Yes, Hydrogen Peroxide the same stuff you can buy at Costco, Sams or any drug store. You probably already have some in your medical supplies as it is a mild antiseptic. It is usually 3%, but strong enough to make the vinegar a super oxidizer that will dissolve lead or break it's bond to the underlying metal.

    850 does seem a little too hot, but whatever works. Have you checked your pot with a thermometer to see if it is really at that temp? 700 doesn't work for me either, since I run two molds simultaneously. I typically need it in the 725-750 range to keep the alloy flowing. I also don't worry about the alloy mix as I shoot range scrap, typically is in the 10-12 BHN range, but since it is powder coated I could shoot pure lead at handgun velocities without worry. Hope some of the suggestions work for you.

    BTW: I have used electrolysis for removing rust from steel/cast iron and that works quite well, but I am not aware of a process for aluminum. I wouldn't recommend ultrasonic cleaning on aluminum either or at least not for any duration.

  2. #22
    Boolit Grand Master

    Join Date
    May 2005
    Castlegar, B.C., Canada
    Something else you might try is to loosen the sprue plate to allow better venting at the top of the blocks. I usually loosen my sprue plates so they almost swing free. On some moulds I find that I have to bevel the top edges of the mould blocks ever so slightly under the sprue plate. This forms a very small V where the mould blocks meet. it only needs to be a few thou so no files! I use a diamond hone to just break the sharp corner.

    Having said that this is usually when bases don't fill out well but the tight sprue plate being loosened and possibly those top corners being just broken will help venting and won't hurt anything so worth a try.

    I would not recommend a file for vent lines! I think country gent has it right... try an awl with good point or scriber or fly fishing bodkin. Something with a decently sized shank or handle and nice sharp point then very carefully score the vent lines, but only if you see something in them. I'd try loosening the sprue plate first then breaking sharp corners at the top of the blocks if that doesn't do it. Then if those don't work try clearing vent lines.


  3. #23
    Boolit Buddy
    Join Date
    Aug 2007
    What Doc Savage said. It doesn't sound like your mold has anything in it that would be a problem. I had a mold which cast good looking boolits on the nose and base, but the driving bands were visibly shrunken away from the mold on one side. I added a 3/4" hunk of bar tin to the 20lb pot and left the mold on top of the pot for 15-20 minutes covered with a sheet of aluminum foil. It cast normally after that. I think the temp was a bit low and the alloy benefitted from the tin. The previous casting session gave indications that it could use some.

  4. #24
    Boolit Master

    HangFireW8's Avatar
    Join Date
    Dec 2008
    Central Maryland
    Quote Originally Posted by Joe S View Post
    Thanks everyone for your comments. The bullets look good superficially, with excellent bases, but the bands consistently fail to fill out. I have tried smoking the cavities, scrubbing with hot water as suggested above, and I do use a hot plate to pre-heat the mold. Have also pre-heated it to the point of almost being too hot.
    I suspect there is some blocking of the vent lines. It is an Accurate Molds product, and the vent lines are very fine.
    I have another one on order, this time in iron, so as of now, the problem mold is basically worthless to me, I might as well try opening up the vent lines. I have a number of small files, not sure exactly what I should use.
    I doubt exploring another dozen ways to clean molds is going to solve this problem. I think you need more pressure. If you are using a bottom pour, either increase the flow rate, or try ladle casting. More tin might also be needed, as has been mentioned.

    I'd like to know which mold you're using. I have a 2 cavity Ideal in 458 where pouring the second boolit would push air into the first cavity and flat side the still molten slug there. The two cavities were very, very close together and vents connected them. Waiting between pours, or using only one cavity would fix the problem. Maybe not your situation, but other than cleaning methods we have very little to go on.
    I give loading advice based on my actual results in factory rifles with standard chambers, twist rates and basic accurizing.
    My goals for using cast boolits are lots of good, cheap, and reasonably accurate shooting, while avoiding overly tedious loading processes.
    The BHN Deformation Formula, and why I don't use it.
    How to find and fix sizing die eccentricity problems.
    Do you trust your casting thermometer?
    A few musings.

  5. #25
    Boolit Buddy
    Join Date
    Aug 2006
    Davenport, IA
    Forgive me if my ignorance on this thread is evident. I'm at lunch and didn't read the whole thing but I did notice that you said your bases are filling out yet you're driving bands are not. To me this indicates a venting problem. I also saw the word file used. You don't need to file. What you need is a carbide scribe with a very fine point. You need to lightly, and I can't emphasize enough that you must do this very carefully, scribe the vent lines. Beginning near the cavities scribe toward the out side of the mold blocks. This can be challenging with Lee moulds given the fly cutter s.tyle vent lines. With other molds that utilize straight vent lines it's a piece of cake. You may need some magnification and a vice to hold your block.

  6. #26
    Boolit Buddy GRid.1569's Avatar
    Join Date
    Aug 2009
    Go back to square one.... clean the mould and get a “controlled” alloy... buy something from rotomeyals and eliminate the concerns about your alloy... if it works then...
    May we achieve our aims....

  7. #27
    Boolit Master gpidaho's Avatar
    Join Date
    May 2014
    Beautiful Idaho
    OP: You stated that you have the same mould, but in iron on the way. It seems you have been very diligent with your cleaning attempts. It's been my experience that for what ever reason, some moulds are just a PITA. Send it off in an Ebay sale and you will have a good start on paying for the new mould. Gp

  8. #28
    Boolit Master uscra112's Avatar
    Join Date
    Jun 2006
    Switzerland of Ohio
    Quote Originally Posted by KenH View Post
    What usually works for me (assuming the vent lines are clear) is take a bullet from the mold, take a dry wall type screw and screw into base of bullet (I use a lathe to be sure its centered, but not necessary), load bullet with a fine grit (5,000 or so) paste (polishing toothpaste?) and spin bullet in mold. Doesn't take a lot, and it won't increase diameter any to speak of when just cleaning. Bullets drop nicely then.
    I've flat ruined an aluminum mould by using a drywall screw to turn a lap. Screw worked right through, and the tip gouged the mould something awful.

    Since then I've drilled a small hole and used a suitably sized Torx bit. Drives well in both directions.

    In the '50s we used Colgate toothpaste, which had finely ground feldspar in it as an abrasive. Then I discovered Barkeepers Friend. Mix with a bit of soapy water. Bon Ami also works.
    flectere si nequeo superos, acheronta movebo

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check