A casting question

lrrifleman · Sep 6, 2021

Today, I was trying to "dig out" my casting equipment from my "workshop", which I hadn't used since the summer before the accident that left me disabled, which amounted to about 15 years. In that time span, stuff just got tossed in, and to top it off, the roof of my workshop developed a leak.

Unfortunately, I discovered a pair of molds I had been using to cast bullets for my 40-65 and 45-70 Highwalls that I hadn't returned to their storage boxes. The bad news is, the exteriors of the molds have developed surface rust. The good news is that there is no rust in the mold cavities and there isn't any pitting.

Having grown up on a small truck farm, my grandfather taught me some tricks. One was to use coca cola to cut through and remove rust. Does anyone here see a problem using coca cola followed by a thorough rinse with water followed by acetone? Would anyone wish to suggest an alternate method for removing the surface rust?

As always, thanks in advance for your help!

glenwolde · Sep 6, 2021

Soak them in white vinegar and rub it off.

Ivan the Butcher · Sep 7, 2021

If the actual cavities are fine, knock off the exterior rust with a wire brush and use as is! If it needs more care, then Coke or navel jelly.

Ivan

STCM(SW) · Sep 7, 2021

Ivan the Butcher said:
If the actual cavities are fine, knock off the exterior rust with a wire brush and use as is! If it needs more care, then Coke or navel jelly.

Ivan

What I have done.

Ruger 13 · Sep 7, 2021

Soak them in Kroil!

IrishFritz · Sep 7, 2021

I believe you should not worry about external rust too much if the cavities are good and the top of the molds and the sprue plates are good. You really don't want to remove the internal heat oxide from the molds as this is an aid to casting performance. My feeling is that as you use the molds and oil them to protect them between sessions the rust will gradually slough off from the preservative oil. I know they may not look very good good but if they still work I'd leave well enough alone.

BillBro · Sep 7, 2021

Not knowing anything about bullet molds and their care and maintenance all I can offer is the suggestion of THE BEST rust remover on the planet, EVAPORUST. It just flat out works like NOTHING else.

2152hq · Sep 7, 2021

Ivan the Butcher said:
If the actual cavities are fine, knock off the exterior rust with a wire brush and use as is! If it needs more care, then Coke or navel jelly.

Ivan

I'd follow this advise.
Stay away from the interior surfaces of the moulds, the cavities and the flat mating surfaces.
If you do apply any oil to help remove rust and old dirt, clear the oil from the blocks before casting.

Sometimes it helps after that to 'smoke' the cavity of the mould so the bullet fills out better and releases from the block(s) easier when the mould is opened.

Some use a match to apply a thin soot film.
I use a candle flame.

I don't like using a match as it carries some phosphorus and other chemicals with it from the strike ignition typical of a match.
That can cause steel to rust and pit if left over the course of a couple days.

You only have to smoke the cavity once, not on every pour. Then perhaps every so often if the bullets starts to hang up in the block when dropped or they don't want to fill completely.

gwpercle · Sep 7, 2021

For the rust ... soak them in Kerosene , big box and wally world sell K-1 Kerosene for heaters and lamps in quart cans .
The kerosene will not affect the cavities .
Coke and vinegar are acids and will etch the mould cavity surfaces .
Kroil is a penetrating oil and will not damage the cavities .
A great , better than Kroil , penetrating oil is a 50-50 mix of acetone and ATF (GM Dexron , non synthetic) ... this will not damage the cavities surface but will lift and get under the rust like penetrating oils are supposed to do .

I'm glad you're back ... Stand firm and carry on .
Gary

mikerjf · Sep 7, 2021

I’d say wire brush it and use it.

But just for the info, I’ll mention that a 10% solution of molasses (10% molasses and 90% water) will gently de-rust submerged parts over a month or so. It turns the rust into free black iron.

4barrel · Sep 7, 2021

Once you get the rust off --get the lead pot hot and submerge the mold for about 5 seconds. That will get the color back. <iron molds only>You may have to do it twice but don't over do it. It will look new. I have a bead blaster for rust and use sugar sand.

Racer X · Sep 17, 2021

sodas have phosphoric acid in them, and depending, citric acid. that's why they work.

cmansguns · Sep 17, 2021

Coke has always worked for me

OP's mention of his dad brought immediate memories to mind. Helping my high school friend with his first "car" (a 1949 Ford Business Coupe)...a real beater...rusted, needed almost everything...three on the tree with overdrive. Anyway..the clutch went out, got some parts and a new(er) pressure plate but danged if we could get those bolts out to drop that old tranny.

Car jacked up in my folks back yard, along comes pop, crawls under, takes a look and says "go get me a coke". No cans in those days, just the classic bottles, go get pop a cold one figuring he's thirsty, forget a bottle opener. Pop crawls out from under, puts the bottle top against the old rusty bumper, wham's down and bingo...top pops off. Neat trick #1 learned.

Shakes it up, thumb over the top, crawls back under and sprays the daylights out of those rusty old bolts. Maybe a half hour later, takes a breaker bar & socket, crawls back under and every bolt came loose. Wow...Neat trick # 2 learned that day.

Don't know how you would do this with modern day cans, but the pressurization and whatever chemicals are in coke (original formula only folks) sure saved the day on an old 49 Ford Tudor.

Greyman50 · Sep 17, 2021

Using most “ sodas/ soft drink” soaked rag will remove lots of minor surface rust on just about any ferrous metal. Have to watch how long you let it sit as it will remove blueing.

mtgianni · Sep 17, 2021

Get an old wooden pencil, yellow #2 if possible. Sharpen it and go over every inch of the exterior with the "lead" graphite. Break the point off and burnish the parts you went over with the wood. New pencils have a plastic exterior and I don't know what the material is that writes. Old pencils were Osage Orange wood in many cases. Keep wire brushes away from molds.

Rifleman200-10X · Sep 17, 2021

I have lots of vintage bullet molds, many of which were not very well cared for. But it matters not what the outside looks like, as long as the cavities are not in horrible shape. Wire brush the crud off the outside, clean and smoke the cavities, and cast away!

A casting question

lrrifleman

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glenwolde

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Ivan the Butcher

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STCM(SW)

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Ruger 13

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IrishFritz

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BillBro

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2152hq

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gwpercle

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mikerjf

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4barrel

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Racer X

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cmansguns

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Greyman50

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mtgianni

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Rifleman200-10X

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