Aluminum mould prep

[faraim]

I just received my first aluminum mould, an MP and can't wait to start melting some lead. Is there any mould prep or seasoning I should do before I begin. I have a brass NOE and have performed the heat treating as suggested by the maker. Just curious if the silver ones need something like that also.

[JonB_in_Glencoe]

I just wash them in Hot water, scrub with dishsoap and toothbrush. That is just to get the residue machining oils off. I would also heat cycle the mold, 2 or 3 times, before casting anything.

[DAFzipper]

My experience with his aluminum moulds is that no matter how much I clean them they take 2 or 3 casting sessions to start good fill out without any rejects. Well, very few of them.

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[kevin c]

I've heard that MP aluminum molds are often good to go straight out of the box, but have always prepped them, and all my other aluminum molds, by degreasing by with an alcohol and toothbrush scrub, deburring the cavities with a softwood stick, oiling the pins and sprue plate hinge, and, once at casting temperature and with the cavities full, rubbing down the top of the blocks and both sides of the sprue plate with sprue lube or two stroke oil.

IIRC, I usually get good boolits the first session.

[DHDeal]

The only aluminum molds I have are Accurate Molds so not exactly apples to apples. Having had over 10 of them, I've learned to clean them real well and start casting. I will run them through my ultrasonic with real hot water, a quick squirt of Dawn, and probably 15 minute cycle or so. I'll reassemble, lube, and start casting. My first session will usually give me some wrinkled bullets at first, but I start to get perfect bullets after any residual oils/whatever gets gone from hot lead being poured in them, or maybe just some oxidation begins on the aluminum. On the second session I get perfect bullets pretty early.

To me, aluminum and brass molds take slightly different techniques while casting, but I more or less treat them the same in the beginning. I clean them well and don't get into a hurry on the first few casting sessions.

[Burnt Fingers]

Aluminum oxidizes within seconds of exposure to the air. Unless you have it in an oxygen free environment it's going to be as oxidized as it can get.

Interestingly enough mercury prevents the oxidization of aluminum, and will remove existing oxidization.....which can be a VERY bad thing. Mercury is not allowed to be carried on an airplane for a VERY good reason.

[gwpercle]

Soaking the blocks in acetone pulls out a lot of oil .
3 complete Heat - Cool cycles seems to help with patina formation and break in .

Or you could just go old school , clean and start casting untill one day they start dropping out nice .
You remelt all the "break-ins" and carry on . Some didn't even clean ...just start casting and expect for it to take a while .
Gary

[quilbilly]

Others will certainly disagree but having been using aluminum molds for over thirty years for my fishing jig business before I started casting boolits, I have used the same process with every new mold aluminum mold whether for fishing or boolits. I get the mold hot by casting at least a dozen groups or single objects then I take a butane lighter and put a light carbon deposit on the inside of the cavities. The mold must be good and hot because there is water in the carbon which can give you an unpleasant surprise (called the tinsel fairy) when you cast your first boolit(s). You rarely have to do this more once a year unless the inside of the cavity is scraped. That molecular layer of insulation or maybe as a lubricant has always made the casting process much easier and faster getting started each session.

[bangerjim]

Buy a hot plate! Before even starting!

Preheat all your molds to FULL casting temp, not just warm as in the old days. I get PERFECT drops the 1st time by doing that. Also heat your feed ingots to 10-15F below the liquidous temp of your alloy. That way they do not pull your pot temp down and there is almost instant recovery when adding them.

I have never cleaned a mold (brass, aluminum, or Fe) in my life and I have dozens and dozens and DOZENS of them. Oil is not a problem with molds, temp of the mold and alloy are the causes of wrinkled boolits. Make sure you have a GOOD lead thermometer and check it.

You can lightly smoke a new mold, but I try them first to see what works. If some problems arise, LIGHTLY smoke the Al mold. Most of my many Al molds have NOT been smoked. Or scrubbed & cleaned & cleaned & scrubbed and cast PERFECT boolits on the 1st drop..............if all the temps temps are right!

Good luck. And remember, this is NOT rocket science! It is a very easy and fun thing to do.

banger

[fredj338]

I just use brake cleaner & a tooth brush. Every mood seems diff but it seems I need a couple 100 bullets to get zero defects.

[Burnt Fingers]

Buy a hot plate! Before even starting!

Preheat all your molds to FULL casting temp, not just warm as in the old days. I get PERFECT drops the 1st time by doing that. Also heat your feed ingots to 10-15F below the liquidous temp of your alloy. That way they do not pull your pot temp down and there is almost instant recovery when adding them.

I have never cleaned a mold (brass, aluminum, or Fe) in my life and I have dozens and dozens and DOZENS of them. Oil is not a problem with molds, temp of the mold and alloy are the causes of wrinkled boolits. Make sure you have a GOOD lead thermometer and check it.

You can lightly smoke a new mold, but I try them first to see what works. If some problems arise, LIGHTLY smoke the Al mold. Most of my many Al molds have NOT been smoked. Or scrubbed & cleaned & cleaned & scrubbed and cast PERFECT boolits on the 1st drop..............if all the temps temps are right!

Good luck. And remember, this is NOT rocket science! It is a very easy and fun thing to do.

banger

You've got to be the only person on this forum who thinks that oil in the cavities isn't a problem.

[lightman]

I only have a few aluminum molds and they are from Accurate and not MP. But I spray them with brake cleaner and use a nylon brush on the cavities and vent lines. I'll do this a couple of times. Then I'll preheat it on my hot plate. When its up to temp I'll lube it about like what is described in the stickies here about mold lube. I'll usually get good bullets after the 2nd or 3rd cast. Occasionally on the first cast.

[Waisting lead]

I like the Lee molds. All I do is fire up both burners on my Colman ,start my lead on the hot one and put my mold.on the other.
I have about a twenty pound pot so it takes a while.
If the mold is new I spray some lacquer thinner in it and wipe it as best I can with a paper towel. Then I flip it over and heat it up fully open.
By the time the lead is up to temperature the mold is ready and, there you go.

[bangerjim]

You've got to be the only person on this forum who thinks that oil in the cavities isn't a problem.

Just telling the facts as I have seen them..MANY MANY times in my years of casting. I have proved it countless times.

"Hear me now and believer me later".

banger

[robg]

i just wash mold ,lube sprue plate, dry, start casting run lead hot .if that doesn't work i use a butane lighter to smoke mold .