Cooling down molds?

[50/50]

I'm new to boolit casting but not casting in general... i.e. decoy weights, sinkers, etc

That being said, I was a Pipefitter/Welder for years and was always taught cooling down metal, especially fitted metal, would cause it to warp. Why then do I see so many guys cooling their molds on a wet sponge or towel? Knowing that molds are made to close tolerances, doesn't this practice warp the molds even in the slightest? More so as time goes on? Thanks

[DeanWinchester]

I use a manicurist fan. Small and compact but moves a LOT of air.
When juggling molds for some real fast pace casting, I will turn the fan on low and have it blowing on one mold as I empty and fill another.

Cooling a mold with water....not me. Not even on a wet towel. Air cooled is fast enough.

[osteodoc08]

It is huge changes in temperature. I'd never place a hot mold into a bucket of water. I use a small fan. It works well and doesnt seem to harm them, at least mine hasnt.

Besides, if you start casting from a cold mold, youre going from <100 to >600 in a small amount of time. That's what theyre designed for.

[JonB_in_Glencoe]

+1 on the use of a small fan.

[Calamity Jake]

I always cast with 2 molds at a time and set melt temp proper for the molds being used and cast
at a pace that will not get them so hot that they need cooling between pours.

[plainsman456]

If i need to cool down a mold i just set it on a 1 in plate for a second.

To cool the sprue plate i touch it to the bench vise for a second.

They make a whale of a heat sink and no water is involved.

[bhn22]

Some guys do cool the sprue with a damp cloth as part of "speed casting". This is done after the sprue freezes, of course.

[BruceB]

Well now.... as the supposed author of "speedcasting", I reckon I'll put in my pennies here.

1. I have over one hundred moulds, and at least half of them came to me as "used". This means that they served MANY different owners, under who-knows-what conditions, some for decades. Many of the ones I bought new have now served for many years and are still in perfect working order despite my heretical practices .

I have NEVER seen a warped mould of any description, including my own which started out brand-new.

2. My moulds are routinely cooled with water, mostly on a WET cloth pad (not "damp", as so many keep repeating....WET, as wet as possible).

3. On occasion, I have plunged a really hot mould completely into a full bucket of cold water for a second or so...... no harm whatever came to the mould or handles. NO warping, even on the longer 4-cavity Lyman iron blocks, where one would expect the greater length of the blocks to clearly demonstrate any warpage....if such warpage occurred. It didn't occur.

I seem to have a habit of actually TRYING many of the practices which "everybody knows" are taboo. In most cases, the taboos are unfounded. This business of mould warpage is one of them. Almost fifty years of casting, and I have yet to warp or damage a mould in all that time.

Because something "sounds logical" does not necessarily mean that it's a fact.

There's no hotplate in my shop; I pre-heat moulds by sticking a corner of the blocks in the molten alloy for a known period. There MIGHT be a fan, but it's for cooling ME, not the moulds. I mostly cast at about 870 degrees with wheelweight alloy, and cool the sprues with water (that WET pad again) ...... and sometimes the mould itself gets set on the wet pad briefly as well.

This is another example of "Never say never", and also "Never say always".

[skeettx]

IF the moulds are getting too hot, increase the number of moulds used !

I normally use two moulds in tandem, but if necessary can go to three, etc

Mike

p.s. fill #1 ,set, fill #2, set, clear sprue, empty #1, fill, set, clear sprue, empty, fill #2, repeat.
I set the moulds on one pound ingots setting on a terrycloth towel.

On my most used calibers, I have sets of the same mould.
Like two double cavity Ohaus 41-210-K moulds :)

[williamwaco]

BruceB + 1 on every word.

Most of the time, I attempt to control mold temperature by slowing down the cadence but when I need more cooling, I use a spray bottle full of water and spray it directly on the blocks. Occasionally I get more aggressive.

The only damaged molds I have seen were damaged either with a hammer, or by slamming them hard enough to wear out the alignment pin holes.
( Not counting rust - of course ).

I am not saying you cannot damage a mold, just that is not as easy as the "experts" say.

[bangerjim]

You don't hold a mold on a wet towel! You tap it quickly on it. That cools the mold down gradually just a bit. I won't warp. Yes, if you plunge it in water or hold it on a cold wet towel for long periods it might (questionable) warp.

I have never had that problem!

And as mentioned above, pouring 700F lead into a cold mold is just the opposite!!!!!!! Heating it up too fast. ALWAYS preheat your molds on a hot plate. Will not potentially warp your mold and you get boolits perfect.......even from the 1st drop. At least I do.

banger

[CIBCasting]

My father in law uses an Aluminum plate about 6" square and 3/4" thick.
He sets the mold on the plate and it takes up heat slowly but faster than the air.

[50/50]

Oh yes.....I agree. Pouring hot lead in a cold mold is the same, only in reverse. Concerning water, I'm not talking about sticking the mold in a bucket of water. Only a fool would do that. I'm concerned about setting the mold on a wet sponge or a wet towel. In my mind that's almost as bad. I was always taught that you never cool metal to the point where it steams. That's too much and too fast. Am I wrong concerning molds? Trying to learn, I've been on YouTube watching all those videos on casting. I see so many guys doing this and when I see and hear that steam and sizzling, I think...boy, that can't be good for that mold. That's why I'm asking you folks. Thanks!

[fredj338]

I would never put a quality bullet mold in water to cool it. I often cast with two molds & alternate them. An alternative is to use a heat sink, like a brick, to set the mold on for a little gentle cooling.

[50/50]

Well, after reading Bruce's reply, I guess I'm getting to worked up about it. I'm trying to learn as much as I can. I think this is a much better place than YouTube although some of those guys do have their act's together. They certainly have done more that I.

[bhn22]

Since we're being honest here, I have never even seen a warped mold. I've had examples from practically everyone (except Mihec). The molds I thought were warped turned out to have peening around the alignment pin holes from rough handling.

[btroj]

I have used a wet rag, dipping in water, and a fan. I currently use the fan and like it. If I weren't afraid of lead poisoning I would just lick the mould to cool it down.....

[WILDEBILL308]

I have used a wet rag, dipping in water, and a fan. I currently use the fan and like it. If I weren't afraid of lead poisoning I would just lick the mould to cool it down.....
You the man, can I watch?
Bill

[detox]

I have used a wet sponge to cool the sprue and sprue plate only. This provides a cleaner sprue plate cut without having to wait so long...epecially when using larger 44-45 caliber double cavity moulds.

[BNE]

you the man, can i watch?
Bill

video!!!

[btroj]

No video, it would only encourage youngsters to enter into risky behaviors.....

[cbrick]

I've used a wet towel, a spray bottle of water and a fan. Never seen a warped mold but I have settled on the fan and casting pace as my preferred method of keeping the mold at the correct temp. Never would I stick it in a bucket of water as was suggested but to each their own.

For those choosing to use a fan use caution to not blow air across the top of the melt, you will increase oxidation tremendously.

Rick

[btroj]

My fan sits next to the pot, melt is well above the air currents.