Mould release

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snurge

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I just cast some bullets today and had a lot of problems getting them out of the moulds.
Basically had to beat the cra...out of the mould.
What's the secret? Is there a release agent I don't know about?
Also how do you avoid flashing on the base of the bullet?
Thanks in advance for any advice.
 
If the mould is new, make sure it is clean and doesn't have any burrs or flash left from the manufacturing process.

If all is well, the next step is to ensure you are running hot enough. I find that bullets that stick most frustratingly at "bright" temperatures often drop cleanly at "frosty" temperatures. These adjectives refer to the appearance of the bullet after casting.

Now keep in mind, some bullet designs are simply prone to sticking. Deep, sharp-cornered lube grooves with shallow draft angles will just naturally stick more than no-groove bullets.

A release agent should never be needed.
 
BattleRife said:
If the mould is new, make sure it is clean and doesn't have any burrs or flash left from the manufacturing process.

If all is well, the next step is to ensure you are running hot enough. I find that bullets that stick most frustratingly at "bright" temperatures often drop cleanly at "frosty" temperatures. These adjectives refer to the appearance of the bullet after casting.

Now keep in mind, some bullet designs are simply prone to sticking. Deep, sharp-cornered lube grooves with shallow draft angles will just naturally stick more than no-groove bullets.

A release agent should never be needed.
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Well said!

I used to carbon up the mold but once I Built a PID for my lead pot, I don't have many bullets getting stuck. While I love my Lee molds the higher end molds work perfect in my experience. I also crack the sprue just before the lead really sets up. I just use my gloved hand to break the sprue.
 
When you get tired of beating on it, buy a can of liquid graphite from Canadian tire and spray it on the inside of the mold and under the sprue. Re-spray every 500 to 1000 bullets. .458 bullets are still .458 after spraying the mold. I never beat on my molds!
 
Perhaps, drag a Q Tip gently over the edges of the cavities.
If any strands are pulled off, there might be some burrs that need to be removed very carefully.
 
Is it a new mold or just an issue with an older mold?
Aluminium, brass or steel?
Are you preheating your mold?
How tight is your sprue plate?
Help us out with a bit more info
 
It's new to me but used.
I preheat the mold and don't get any initial rejects.
It's a steel or iron mold.
I do pour fairly cool so if I pour hotter I might get more shrink but I like the bullet size I get now.
The spruce plate is as tight as it'll go.
 
I have also used an old electric toothbrush and toothpaste to polish the cavities. Works very well
As for the flashing; is the underside of your sprue plate clean and lead free?
 
Use some wooden matches and let the flame blacken they mould. Then once it’s hot it should release. If it’s a big iron mould pour like 10-12 rejects until it’s hot enough. Use a blowtorch to help
 
BattleRife said:
This is not necessarily the best approach. Some moulds you will get cleaner bases if the sprue plate has just a bit of play so it can settle flat. If it's too tight at one end it might tilt the plate and cause it to be high at the other.
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I agree, one of my arsenal molds the sprue plate will lift over the far 2 cavities if I tighten it too much causing flashing. Also one of my 30 cal molds will get flashing if I pressure pour. I have to fill slowly and let the lead swirl in.
Seems each mold has its own personality
 
No doubt sooting your mold will help with the release, i have found when breaking in a new mold it helps with fillout as well.
The way I look at it though as sort of a bandaid, personally would rather find out why it isn't releasing bullets.
 
snurge said:
I just cast some bullets today and had a lot of problems getting them out of the moulds.
Basically had to beat the cra...out of the mould.
What's the secret? Is there a release agent I don't know about?
Also how do you avoid flashing on the base of the bullet?
Thanks in advance for any advice.
Click to expand...

Clean the cavities with boiling water, dish soap, and an old toothbrush. Rinse with boiling water. 3 minute job. Leave handles on to clean makes it easier to handle.

Flashing on the base usually from spruce plate fit or not letting it cool long enough before cutting. Loose tension better for sprue plate tension, esp on multi cavity molds.

Sticky bullets can be from low temp or contamination. New molds can have machining lube on them.
 
All good suggestions!
Thanks all!
I'm sure the temp is too low,I'm using an old propane stove that burns yellow instead of blue.
What is the best temp range?
 
snurge said:
All good suggestions!
Thanks all!
I'm sure the temp is too low,I'm using an old propane stove that burns yellow instead of blue.
What is the best temp range?
Click to expand...

Hard question to answer unless you've got a thermometer in your mold. You want the mold somewhere around 300-350F because it's the mold temperature that matters, not necessarily the pot temp. You can preheat the mold, and pouring warms it up too of course. If the sprue takes less than 3-4 seconds to solidify then the mold is probably too cold.

If you start with a cold mould you might have to make 10-20 pours or more to get it warmed up (dependant on bullet size and qty) before bullets drop nicely, so any amount that you can preheat will save you time. Bigger bullets warm up a mold faster. More cavioes warm up a mold faster.

What you can do is get your pot hot, then wash or soak the mold in boiling water for a couple minutes, shake it dry, and give it a 1/2 minute to let the heat dry it. Then start casting immediately. Your mold will be preheated to about 200F internally and you're 2/3 there.
 
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I'm going to dispute Jethunter's numbers a little bit. Mind you I have only recently started closely paying attention to temperatures: until six months ago I cast using the pot factory thermostat and preheated the mould with a few dummy casts and didn't measure any of it. But now I'm having a lot of fun putting my data logging laptop to a new chore.

Anyway, I was casting yesterday and confirmed numbers I had seen previously, namely that the mould (a Lee 6-cavity .38) had a very tight preferred operating range, and it was significantly hotter than 300-350F. Cutting sprues was acceptable at 220°C but the effort required rose rapidly if temperature dropped below that number. On the other hand, if I opened the mould while it was hotter than 240°C I would start getting hot tearing at sharp shoulders. After a little while I fell into a groove where I would try to fill the mould when it was between 225-235°, watch the temp jump several degrees with the addition of hot lead, wait a few seconds, cut the sprues, then if necessary wait until the temp fell to 235° before opening the mould. Repeat. The melting pot was not on a PID during yesterday's session and the temperature swung pretty widely. It didn't seem to matter, as Jethunter said the mould temp is really the important one.

I have only worked out technique like this with this one mould. It could be that different mould materials, or a different bullet, or a different alloy would change this working temp range considerably. So the number of 300-350°F may well be correct in some situations, but it would not have worked very well with the arrangement I cast most often.
 
as mentioned earlier using carbon black as a lube works on most of the moulds I use. both aluminum and steel. I use a calcium carbide acetylene generator for sight blackening, but it works a treat on the moulds as well.
No measurable different in size, especially if you are running them through a sizer/lubricator.
The carbon black seems to work for anywhere from 30 to 50 casting cycles, and then a quick blast of acetylene flame and you are ready to go. Mould temp is critical and I prefer to have it warmer than the minimum.
 
I've had a coupld of molds that gave some "sticking" problems. I took a bullet cast from the blocks and drilled a smallish hole in the base and inserted a small screw so I could turn the bullet in the cavity by hand. Coated it with "JB BOREPASTE", inserted into the offending block and twirled a few times. Cleaned up whatever was causing the problem, likely a smallish BURR?? Problem solved.
I know several guys don't like using it but years ago I bought a small bottle of "Mold Release". I think it's Moly in an alcohol solution? I use occasionally to coat the mold cavities, works like a charm and you only do it once every 1000 or so??? I've tried "smoking the cavities" but in my opinion, this works better. The bottle I bought, perhaps 30 years ago, is still on my shelf, perhaps 1/2 full, so little is needed. I've cast 10's of 1000's of rifle bullets using this release agent, I like it, not everyone does.
 
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