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Thread: Brass MP

  1. #1
    Boolit Buddy nueces5's Avatar
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    Brass MP



    hello, I have a brass mp mold for a couple of years
    every time it costs more for the boolits to fall when you open it
    I clean it with a toothbrush and soap before using it, and I lubricate it with the lubricant that the MP molds bring
    Today I rubbed the cavities and the vent lines with a piece of wood, then cleaned it with brake cleaner.
    no apparent improvement
    Is there any way to clean it better than the ones I used?

  2. #2
    Boolit Buddy Krh1326's Avatar
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    I am by far , not an expert, but I get great fills after I prep a mold, brass or aluminum.
    I do not take a lot of the steps that you do, but I clean it thoroughly with brake cleaner and toothbrush, then again with alcohol and qtips.
    Here people will smoke or use some kind of other product, maybe. But I don’t smoke it. I learned this and have run great with both aluminum and brass.

    I have a little jar of alcohol, that I dissolved chalk line dust into.
    I did a qtip in it, and coat the cavities. The alcohol evaporates, and that leaves a fine dusting of chalk.
    No wrinkles, no stickers…. They literally jump out of mold, in great shape.

    I also don’t use the lubes, and I don’t use 2 stroke oil.
    I do apply a very small amount of Copper Never Seize to the alignment pins and bolt, bushing of sprueplate pivot. I honestly think that liquid lubes can find their way into cavities, though I’ve heard some purposely apply Kroil.
    Last edited by Krh1326; 08-06-2022 at 11:13 PM.

  3. #3
    Boolit Buddy nueces5's Avatar
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    great advice!!

  4. #4
    Boolit Buddy Krh1326's Avatar
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    Ty, I hope it helps you.

    The chalk dust / alcohol is not really exact science. No matter what concentrate I make the alcohol is always evaporating…. In time it’s thick at bottom, thin on top. Don’t let too much build up in mold. If it looks like there’s a lot , or too much staying in mold. Dip qtip in straight alcohol, and run it through cavity , wipe out any large dust deposits…. Just want a thin film

  5. #5
    Boolit Buddy
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    I just smoke to start. Then latter if it needs again. Aluminum or steel molds>>

  6. #6
    Looks like you have some tinning there - you need to get that lead off the faces of the blocks. Mal Paso and others here had some great advice on getting these brass MP molds to run. See here for some threads
    https://castboolits.gunloads.com/sho...ipe&highlight=
    https://castboolits.gunloads.com/sho...aring-to-Mould

  7. #7
    Boolit Buddy nueces5's Avatar
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    thank you very much everyone, I'm going to clean as best I can, and then I'll try with the chalk
    my daughter has chalk to steal
    when I bought this mold I did 3 heating cycles in the oven that I use to bake the PC, I don't remember if I left the mold with the faces together or apart

  8. #8
    Boolit Grand Master

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    I scrub with a medium toothbrush and acetone , If acetone scrubbing doesn't clean everything off ...
    I get out some 0000 steel wool and wood skewer and very carefully rub the places that are still caked ... That steel wool may be too rough on the brass ...lets think about that !
    Be very gentle ...the brass is soft and the steel wool , is steel wool and will cut... brass or copper wool may be better for inside the cavity cleaning ... you don't wont to scratch the mould .
    Maybe a super fine polishing compound on a Q-Tip to polish out the cavities would be even better .
    Just be careful ... brass is so soft .
    Gary
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  9. #9
    Boolit Grand Master
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    DO NOT USE STEEL WOOL!!!

    Use a sharp edged piece of wood--I use shiskabob skewers-- and a propane torch to heat the mold and then scrape those bits of lead out of the vent lines. Once you get the mold cleaned up, make sure that you keep the mold closed tightly when filling.
    _________________________________________________It's not that I can't spell: it is that I can't type.

  10. #10
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    I heat the mold the use a alloy bar to remove the tinning by rubbing the bar on bad spots on the the mold face. It works on the sprue plate too.
    Steve,

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  11. #11
    Boolit Buddy nueces5's Avatar
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    thank you all, I think that if I try all the methods I have a 110% chance that the mold will be clean!


  12. #12
    Boolit Master


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    If you notice all the leading is happening where the mold is the thinnest between cavities. No leading or tinning at the nose of the bullet. So the mold is getting too hot in these areas and tinning is occurring. Try a lower lead temperature, cast slower or wait longer before opening the mold.
    Clean the mold as others said. The tinning is causing the boolits to stick.

  13. #13
    Boolit Master Tripplebeards's Avatar
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    That tinning imo is sticking your boolits to the mold. I have the same issue. I’ve used methods above that have been said not to use. It’s the only way I can get tinning out. Once it’s out put some heavy patina on your mold. Check my post above about braking in a new mold. You can see how dark I made it. Don’t know it it will keep tinning at bay but it might help. Imo it’s caused from running your mold and alloy way to hot. I’m guilty as charged but make great boolits when I do.

    Here’s my new mold I just used vinegar and salt fumes to give it a heavy patina. Other than the tinning your mold looks brighter than my new unused mold I just a gave a patina to. I’ll find out if it helps shortly.


  14. #14
    Boolit Master

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    Quote Originally Posted by Minerat View Post
    I heat the mold the use a alloy bar to remove the tinning by rubbing the bar on bad spots on the the mold face. It works on the sprue plate too.
    I'll bite, what's an alloy bar?
    “Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem.” Ronald Reagan


  15. #15
    Boolit Buddy
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    An ingot of the alloy you are using.
    Last edited by cupajoe; 09-27-2022 at 02:09 PM.

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