Mold contamination - cleaning

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  • Last Post 26 March 2012
Balhincher posted this 01 November 2009

I have a new aluminum mold that refuses to cast wrinkle free bullets.  I have scrubbed it with different solvents as well as hot soapy water and boiled it more than once.  I've cast with very hot alloy (700+ degrees) for extended periods of time and still get defects every last time with this mold.  I've used the same alloy at the same time to cast perfect bullets with several different molds so I don't think the problem is the alloy composition or temperature.

I apparently contaminated the cavities and may have done it with over zealous application of Bull Plate lube.  I'm not pointing a finger at that product but it may be the thing causing wrinkles.

It has been suggested to me that I try baking it in an over for several hours to try and vaporize and get rid of whatever is generating the wrinkles.

Questions:

Has anyone experienced similar problems when using Bull Plate lube and if so how did you clean it off the mold?

Will it damage an aluminum mold to heat it for an extended period of time to a temperature of 200 degrees?  300 deg? 400 deg?  Will this undo heat  treating for the aluminum  (it is listed as 2024 alloy)?

Has anyone ever tried this to get rid of grease, oil, etc. that causes wrinkles and resists removal by the usual methods?

I've tried cleaning the mold repeatedly and have been stymied so far in removing whatever is causing the problem.  Any suggestions about how to get this mold working would be appreciated.

Making it even more frustrating is the results I've gotten shooting the bullets with wrinkles.  I've gotten some pretty decent groups (1-1/2 inch 5 shot groups with a .357 Max Handi Rifle at 50 yards) even with the bad bullets.  It is tantalizing to think what might be if only I could cast some good quality bullets.

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CB posted this 01 November 2009

700 degrees isn't really that hot. I have an LBT mould that shows wrinkles in the base on 2 cavities unless I cast fast & furious, using a maximum of 2 moulds. If I try casting with 3 2 cavity moulds, it soon cools down to the point of wrinkling again. There's nothing wrong with the mould, it's just being difficult. If you have a lube fouled mould, the lube can usually be removed with lacquer thinner. I think your mould might just need more heat, and/or a faster casting pace.

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303PV posted this 01 November 2009

Are the defects always at the same spot? If they are it may be caused by insufficient venting. Or the vent lines are clogged. You can try cleaning the surface with a brass brush. Don't overdo it , because brass will scratch aluminium . But also try a higher temperature as suggested by anachronism.

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99 Strajght posted this 01 November 2009

Have you tried smoking the mold? All of my aluminum molds work better after they have been smoked.

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CB posted this 01 November 2009

Try turning the melt up to about 780 degrees and sticking the corner of the mould into it until it smokes. Once it starts smoking continue to hold it in for about a 10 count and see what happens. I see no use in casting at 700 degrees if the pot will go higher. If you're using WWs and getting shiney bullets do yourself a favor and look for frosty.

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kidwalli posted this 21 September 2010

Clean with alcohol and Q tip. Smoke liberally with Zippo lighter or wooden matches. Lube sprue plate and mating surfaces SPARINGLY with bees wax. 750 to 800 degrees or just until bullets frost.

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hunterspistol posted this 21 September 2010

      :coffee  I use alcohol after I clean, sometimes I just pour acetone over it and wipe with a clean rag.  Don't be afraid to pour an evaporative cleaner over it afterwards.  Clean tee shirt material is good because it's low on lint.

    

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Dollar Bill posted this 24 September 2010

pat i. wrote: Try turning the melt up to about 780 degrees and sticking the corner of the mould into it until it smokes. Once it starts smoking continue to hold it in for about a 10 count and see what happens. I see no use in casting at 700 degrees if the pot will go higher. If you're using WWs and getting shiney bullets do yourself a favor and look for frosty.Good advice. I bought my first aluminum mold this year, a Mihec for my 44 Special. I wasn't getting very good results until I followed Tim T's advice: Run it hot and go like hell". Works like a charm.

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CB posted this 24 September 2010

Ah I see you got some Bull Plate in the cavities.

That is a real PITA, after I scrub it out well with Dawn (works the best at breaking up oil & grease) I spray it out with Brake Cleaner (the flammable type cheap at Walmart under 3.00 a can) and let it dry. I use Rapine Mold prep between the top of the mold and bottom of the sprue plate, I like it because it is applied cold and is alcohol based and dries quickly. Then I get my pot up to temp (800 degrees F) and stick a corner of the mold into the lead for about 1 minute or as long as it takes to get up to temp, then I pour. If you do it right, it will take a longer amount of time for the sprue to solidify, but that is okay. Pop the sprue and go at it, it should produce very good bullets.

The reason that this works is because the aluminum is somewhat porous, heating it expands the pores and hopefully burns off any remaining oil or grease. If it doesn't, hit the hot mold with the brake cleaner, spray liberally on the inside, let it all evaporate and then stick in back into the mix to get hot again and repeat until the quality of your bullets is what you want.

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jppr26 posted this 24 September 2010

I use lee molds and a lee pot i usually get my molds good and hot then smoke them good with a acetylene torch and get more of a good sooting then smoking but also a hot mold with no releasing agent works for me, if i even get a bit of wax or something in the cavity's they come out all pruney then it takes a few dozen casts to get them good again.  Also i run my pot at #8-10

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onondaga posted this 17 November 2011

My 2 newest molds are both Lee, I recently got the 18 cavity 00 Buck mold and the RanchDog .460-350 FNGC 6 cavity.

I have not changed my mold preparation before use in many years and have had no problematic Lee molds.

I disassemble the molds and scrub them with a Comet and water paste and a small brush. Then I rinse thoroughly with hot water, wipe  and allow to dry.

I lube the guide pins and where they fit with silicone dielectric grease very lightly just enough to get a shine on the metal. I lube the sprue plate and mold block top the same way. I also use the silicone on the screws, bushings, washers and tapped holes; all very lightly.

This works well for me and I believe the gray discoloration from the Comet is an oxidation layer that assists in easy release of the cast bullets.

I never use any products that have petroleum or petroleum distillates on any of my molds. I believe penetrating oils do just that and penetrate aluminum leaving oil there to boil and gas out and cause casting defects. Those defects are generally crater shaped.

Wrinkle defects in bullets is generally caused by insufficient mold temperature and/or  a slow pour into the mold or low head pressure from a low pot or over closed flow valve that diminishes flow volume and speed into the mold.

There is a simple method I use to assure that my mold is hot enough to get a good pour on the first or second pour. I rest the mold block bottom contacting the rim of the melting pot as much as possible for at least 30 minutes before casting a fresh pot.  I use a 1 pound ingot on top of the mold to hold it down on the pot top. This 30 minutes can include the melt time when I briefly remove the mold for fluxing the pot before beginning to cast.

 I flux with a pea size piece of bees wax in my Lee 4-20   when metal is hot enough to ignite the flux. I stir then skim and then sprinkle the melt top with saw dust. Sprues are added at the beginning of the next melt for 2 cavity molds but hot sprues from 6 cavity molds are dropped right into the pot. I generally cast everything at 720-750 degrees F. and adjust my casting cadence for bullet quality between 3-4 casts per minute.

Gary

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TRKakaCatWhisperer posted this 18 November 2011

Wrinkles:

a) mould too cold or melt too cold

b) too slow in filling

Mould at 400+ df and melt at 700-750. That means that in a LARGE mould using a bottom pour pot you might-could get wrinkles but with a dipper (with a larger hole) you will not.

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777artyH posted this 26 March 2012

Aluminum molds are wonderful, but not only do they heat up fast, they also cool down just about as fast. I use a propane torch to pre-heat my mold to ensure it is not just heated from one side. Dipping a corner into the pot will certainly heat the mold but a torch can be used to heat the fingers of the mold handle that grasp the mold too. Remember, the mold handle acts like a heat sink and sucks away heat. Get the mold hot and go like hell is the best advise I've seen so far.

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777artyH posted this 26 March 2012

Aluminum molds are wonderful, but not only do they heat up fast, they also cool down just about as fast. I use a propane torch to pre-heat my mold to ensure it is not just heated from one side. Dipping a corner into the pot will certainly heat the mold but a torch can be used to heat the fingers of the mold handle that grasp the mold too. Remember, the mold handle acts like a heat sink and sucks away heat. Get the mold hot and go like hell is the best advise I've seen so far.

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Wayne S posted this 26 March 2012

If you are casting with just one mold, like the others have said 750+ deg. alloy, espically WW alloy, and cast fast, if these are long bullets , let air dry, do not water drop as they will warp or crack “ask me how I know” If using two molds, get a single burner hot plate, put an old 7 1/2” saw \blade on top  so the mold has a flat surface to sit on, fill mild, set on hot plate while sprue hardens, process 2nd mold, fill and sit on hot plate.

WayneSend

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