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Thread: Brass mold wrinkled boolits?

  1. #1
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    Brass mold wrinkled boolits?

    Got my first brass mold a month ago, finally got a chance to use it. Quality looks great, I.e., tight fit, good alignment, lots of vent lines. However, I kept upping temperature and was still getting pronounced wrinkles at 25C above my normal temperature for my old SAECO irons. Manufacturer FAQ states they are shipped without any preservatives. Any thoughts as to why? Alloy is 50/50 coww and soww. Pid is Celsius only.

  2. #2
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    Txcowboy52's Avatar
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    I would try cleaning it really well, and Ive even found smoking the mold some times helps. I hope you get it worked out , good luck.
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  3. #3
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    More heat! Heat that mold hot too!

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    Boolit Master uscra112's Avatar
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    Yup. mold is too cool. Increase your cadence. Filling the cavity as quickly as possible will also help. Are you keeping your ladle hot?

    Brass has a high capacity for heat. Not like aluminum or even cast iron. Some people set a hot plate alongside the pot to heat the mold and keep it hot if for any reason they have to break cadence.
    Eleutheromaniac

  5. #5
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    Quote Originally Posted by uscra112 View Post
    Some people set a hot plate alongside the pot to heat the mold...
    Yep. Heat the mold up on a hot plate, and once you get it up to a temperature where the wrinkles are gone, just keep casting. Got about a dozen brass molds and they are the best.

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  6. #6
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    HATCH's Avatar
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    Machining requires lube.
    You need to always clean the mold first prior to casting.
    Brass molds like to stay hot.
    So you need to increase the amount of time you are keeping the lead in the mold and shorten the amount of cool down (time between dumping and loading)

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    Brand new Brass mold...I would heat cycle it 3 or 4 times, to start a oxidation layer (the first stage of patina).
    Then cast with it. Brass likes to be run hot. when you start getting unwrinkled boolits, that the mold temp you want.
    In general, any new mold "may" not cast well during the first few sessions. Just keep at it.
    ~~~~~~~~~~~~~~
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  8. #8
    Boolit Grand Master OS OK's Avatar
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    I would just stop...take a breath and start over again as if it were a new mould out of the box...

    Disassemble, boil it for about 20 miutes, 3 times...first two with some Dawn detergent in the boil, last boil with fresh water only.
    Your removing all the oils from machining and any that you have added lubing the mould.
    (add water to the pot as you pour it off into the sink, keep the oils on top of the water as you discard the water and fill for another boil)



    Next...3 heat cycles in the oven @ 400...let it cool to the touch between cycles.
    You are allowing a new micro-patina to form in the cavities so you will not have to resort to mould release or smoking the cavities.





    Reassemble...use 'anti seize', a high temp lubricant/protector of threads and sliding surfaces. Put it sparingly on the mould pins, on the underside of the sprue plate (this you rub in well and wipe the surface so you don't see it, but it is there sealing the pores of the metal plate...use it on the washers at the hinge of the plate and on the threads of the screws.



    (there are many other steps involved in reclaiming old moulds but they don't apply here...your mould is new)
    Preheat that mould to 300 ~ 400 prior to casting, preheat while your pot is being loaded & prepared for a run.



    Now cast away using whatever techniques you have learned for yourself, pay attention to each casting...do not peruse the individual cast, just take note of the temperature of the melt and whether it is hot enough or too hot, you determine that...get to casting and set your cadence so that you get clean sprue cuts on the bases, no tearout of material.

    Use any or none of my suggestions here. I've been called 'OCD' and am quite proud of that title as I usually don't have troubles reclaiming & casting the used moulds I have collected over the years.
    I think casting is like painting...your success depends on your preparation efforts.

    When I put my steel & brass moulds away, I coat them with a liberal coating of Mineral Oil USP...





    I used to use WD40 but it is out ever since someone turned me on to the Mineral Oil. I hit the cavities and inside faces of the mould with a quick spray of brakeclean, not necessary as the M-O will burn off and doesn't wrinkle the cast. Leave it on the outer surfaces of the mould and it will forever protect against rust.

    I store the steels in a little box from the hardware store...

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  9. #9
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    A brass mould is a little different than aluminum or steel. They sometimes need a break in period to develop the "patina" that makes them cast well. 3-4 short sessions and allowing t to cool between. Or heat in oven to 350*-400*and slowly cool 3-4 times. This promotes the "patina" to form. This helps the mould fill out and release. Clean the mould with a tooth brush and dish soap before sessions lightly lube sprue plate pin and plate. Ideally pre heat on hot plate. Brass holds heat longer but my brass moulds tend to cast around same temp as steel

  10. #10
    Boolit Master uscra112's Avatar
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    Generally speaking, the working mould cavity temperature should be about the same no matter the material. Low enough to make the lead solidify, but not so low that the lead starts to solidify before the cavity is filled. (That's what makes wrinkles.) The specific heat of brass is almost twice that of cast iron, on top of which brass moulds weigh more, so they are very slow to heat up compared to iron. But once a brass mould is there, it will also be the slower to change if your cadence gets interrupted, which I regard as a plus.
    Eleutheromaniac

  11. #11
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    Heat................heat...........and MORE HEAT!!!!!!!!!!!!!!!

    Brass molds like to run hot......hotter than Al molds. You can boil and clean and scrape and scour until you wear the brass down, but oil is not your problem. You need to preheat on an electric hot plat to FULL casting temp (not just warm).

    I have numerous brass HP multicav molds and they went right out of the shipping box to casting (after 3X heat cycling to build up the golden patina you MUST have to prevent tinning) with ZERO scrubbing and cleaning. Preheated on a hotplate, they drop perfect boolits from 1st drop. I have NEVER cleaned a mold. And I have many MANY dozens of them - brass, Al and Fe.

    Get the mold HOT. And make sure you alloy is good and hot. Frosted boolits (over-heated) are better than wrinkly ones any day.

  12. #12
    This may not be the same..But I have a large Bullet mold made from aluminum..I am talking 1 1/2" Diameter Bullet weighing near two pounds though..I always get wrinkles..I think is related more to the casting mold material than my poor casting..

  13. #13
    Boolit Grand Master OS OK's Avatar
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    Quote Originally Posted by Carbineone View Post
    This may not be the same..But I have a large Bullet mold made from aluminum..I am talking 1 1/2" Diameter Bullet weighing near two pounds though..I always get wrinkles..I think is related more to the casting mold material than my poor casting..
    This might be a problem with getting the lead into the mould fast enough?
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  14. #14
    Boolit Master uscra112's Avatar
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    Quote Originally Posted by bangerjim View Post
    Heat................heat...........and MORE HEAT!!!!!!!!!!!!!!!

    Brass molds like to run hot......hotter than Al molds. You can boil and clean and scrape and scour until you wear the brass down, but oil is not your problem. You need to preheat on an electric hot plat to FULL casting temp (not just warm).

    I have numerous brass HP multicav molds and they went right out of the shipping box to casting (after 3X heat cycling to build up the golden patina you MUST have to prevent tinning) with ZERO scrubbing and cleaning. Preheated on a hotplate, they drop perfect boolits from 1st drop. I have NEVER cleaned a mold. And I have many MANY dozens of them - brass, Al and Fe.

    Get the mold HOT. And make sure your alloy is good and hot. Frosted boolits (over-heated) are better than wrinkly ones any day.
    I recently bought a brass mould from NOE. Didn't even heat-cycle it. Just heated it up and started casting. Good bullets right away, and no dropout problems. I assume NOE washes the cutting fluid away before packing the mould for shipment.

    I have only one gripe about brass moulds and that's the weight. I have to use toggle type handles; old hands, arthritis, weak grip. They're heavy enough, and brass adds to that. Else I'd have nothing but brass moulds.

    @Carbineone: It's not so much that your big mould is aluminum, it's that you don't have it hot enough as you start your pour, and/or your lead isn't hot enough, and/or you're filling the cavity too slowly. Aluminum does draw off heat more quickly, so you have to compensate.
    Eleutheromaniac

  15. #15
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    Quote Originally Posted by uscra112 View Post
    I recently bought a brass mould from NOE. Didn't even heat-cycle it. Just heated it up and started casting. Good bullets right away, and no dropout problems. I assume NOE washes the cutting fluid away before packing the mould for shipment.

    I have only one gripe about brass moulds and that's the weight. I have to use toggle type handles; old hands, arthritis, weak grip. They're heavy enough, and brass adds to that. Else I'd have nothing but brass moulds.

    @Carbineone: It's not so much that your big mould is aluminum, it's that you don't have it hot enough as you start your pour, and/or your lead isn't hot enough, and/or you're filling the cavity too slowly. Aluminum does draw off heat more quickly, so you have to compensate.
    Agree! Lack of HEAT on the BIG Aluminum mold is likely your problem. That's where the good old electric hotplate comes in. Heat that mold WAY up there in temp and try it. I bet will will cast good boolits. I have a 5 cav round ball mold that way. I casts 1.1" diameter round balls I use for various weights and it needs to be SMOKIN' (literally!!) HOT before ever pouring the 1st drop of alloy.

    Brass ones are heavy! But they are now my standard for any new mold.

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