View Full Version : So what's wrong with frosted boolits?

05-30-2010, 06:38 PM
I don't know how this occurred at 630F, but I was dropping very frosted boolits today. Mould: Lee 90358 (255 gr. .45 Colt) two-banger, Leemented, Lee 10 lb bottom pour. The thermometer is a WIKA, so it's good quality (and checked against another) and flux is beeswax. The alloy should have been near Lyman #2, blended from some lots of WW, and 50/50, per LASC. I don't know how to measure the temp of the mould, but it didn't seem unduly hot. (Bullplated, BTW, with extraordinarily satisfactory result.)

Frosted, like satin. :shock:

So looking at this pile of frosted boolits (some, but few, not), I says to myself: self, what's so wrong with frosted boolits?

Seems like they'd hang on to tumble loob (45/45/10) like the devil himself.

That can't be a bad thing, eh?:confused:

I will be sizing these.

05-30-2010, 06:47 PM
yep frosted boolits hold more lube. :D

05-30-2010, 07:11 PM
There's nothing fundamentally wrong with evenly frosted boolits. It's a sign of a hot mould and usually frosted boolits exhibit very good fillout. I have moulds that require frosted boolits with my alloy. Not all moulds or alloys require this. As long as there's no other issues with the castings then shoot 'em and see. Chances are you'll develop a fondness for frosty boolits.

05-30-2010, 07:52 PM
I have to run a lot of my Lee molds hot enough for good fillout that I get frosted bullets. Never noticed a problem as long as they were all frosted consistently, but then I 'm not that good a shot!

05-30-2010, 07:57 PM
Well, I think I can accept frosted bullets from this mould. The frosting is very even in the large majority of them, and the fill-out is very good.

But it's got me wondering what constitutes a "hot" mould and how I can measure the temperature.

The mould couldn't have gotten hotter than the alloy (which never topped 650 and was hovering mostly around 630.

What is too hot and is there a way to monitor the mould temp?

Maybe this is one of the experience and judgment aspects of casting (which I'm really getting hooked on).

05-30-2010, 08:14 PM
Some people use an infrared thermometer, but they don't seem to work real well for shiny surfaces such as aluminum and molten lead. You could maybe (carefully) paint one side of your mold with some VHT or other high temperature paint in a flat black and get better results.

I built a dual PID controller with components form Auber instruments, one of the parts was a thermocouple that screws into a 1/4-20 threaded hole. I threaded into a lead ingot to control my hot plate used for mold and ingot pre-heating. I plan to finish making some test molds soon that will be drilled and tapped in the side for this thermocouple so I can monitor mold temperature.

If you're handy with tools you could drill and tap your mold and get a cheap multimeter with a type K thermocouple input at Harbor Freight and get the proper thermocouple from Auber. Then you could monitor your mold temp while you cast. Might be interesting to know what temp works best, and you could also preheat your mold to be sure it's hot enough for the first 1-2 pours to give good bullets.

Might put you out $25-$35 total (I've seen HF multimeters for $10-$15 and the thermocouple with shipping will run about $15, plus a couple bucks for a good tap and a tap drill) but you could use it on any mold, it's easy to screw in/out.

Just a thought.

05-30-2010, 08:15 PM

When I first got started casting, I had the impression that frosted boolits were a really bad thing. As I learned and gained experience, I found the opposite to be true. Severe frosting with crystalline looking surfaces is bad but the light consistent smooth satin like frosting will get you a lot of bollits in a reasonable period of casting. I have a few mold that I can cast nice shiney little boolits but it seems that I can't seem to do it with all of my molds. Why worry about it if you have good, filled out boolits? They will shoot just as well as the shiney ones!

As for monitoring the mold temp, I am sure one could with an electronic pyrometer, but it would slow ones casting and with experience one can easily tell if the mold is getting too hot. My nickels worth....


05-30-2010, 08:24 PM
The advice from Lyman (CBH and loading handbooks) about frosted bullets and hot molds is somewhat misleading. It may well be generally accurate, and be reasonably adequate instruction for the beginning caster using, say, 20:1 lead alloy-- but it does not hold true in many cases with others using varying alloys.

This idea that frosty=bad seems to have started when Lyman published that "properly cast bullets will have crisp edges, and appear clean and bright." OK, so far. But a frosted and well filled-out bullet may also be properly cast. Also, note carefully that the Lyman books never say that there's anything wrong with frosted bullets, just that frosting may indicate a high melt temp. Somewhere along the way, someone (mis)read that to mean frosted bullets were "bad" and this misinterpretation has been repeated endlessly.

Lead with any significant alloy content will often pour frosty bullets. Your lead has significant alloy content, and I would anticipate frosted bullets from many/most casting sessions. Some specially-engineered lead alloys will pour shiny-bullets-- such as linotype will often pour mirror-like bullets-- but many other alloys with significant alloy content will pour frosty bullets.

The instructions that come with LEE molds say the following:
"Frosty bullets may be desirable when using Lee Liquid Alox. Our tests indicate that the lube adheres better and they can be shot at higher velocities without leading."

The observant caster/handloader will note that not only does Alox adhere better to the frosted surface, but wax lubes adhere better to the frosted surface in the lube grooves. It's a win-win situation.

Regards, and good shooting. :drinks:

05-30-2010, 08:28 PM
While I was writing this, there were two subsequent posts.

That is such an elegantly and sensible solution, perfessor, that I'm embarrassed I didn't think of it myself.

Got taps from 0000 to over an inch, some most folks never heard of, so that capital expenditure isn't needed and I have no excuse not to do it.

Or overdo it. Why not monitor the actual mould in play at the time? I understand that the heat zones of a mould in use would be dynamic, but it could be a instructive exercise.

And it does seem like the mantra is "frosted=bad. RCBS repeats it, or at least leaves that impression. I got lovely shiny boolits when casting with linotype. Right nice to look at, don't know how they will shoot.

I need to redirect my focus. This is a very interesting undertaking, this casting business.

05-30-2010, 08:39 PM
Thanks for your responses. Looks like I was rediscovering the wheel.

And I must add that the citric acid bath is a revelation.

05-30-2010, 09:02 PM
Yup, many people have gotten the idea that frosted=bad from reading and carefully following the pouring instructions from reloading and mold-manufacturing companies. Ya can't blame folks for following the instructions! Some of the instructions could be better written. Just one of those live and learn things, and why we have forums like this.

05-30-2010, 09:04 PM
You couldn't be more on, sag.

But I have learned to trust my own progressions and listen to advice here.

05-30-2010, 09:08 PM
Sounds like you're livin' and learnin' right along with the very best of 'em.

Regards. :drinks:

05-30-2010, 09:10 PM

Didn't I just see this in a thread yeasterday?

05-30-2010, 09:20 PM
sag: hopefully.

Deja vu, all over again? I suppose there is a lot of pleonastic repetition and redundancy in Internet forums. Search engines aren't honed, appellants are lazy, stuff happens.

If it was discussed, I missed it. Or it missed me.

05-30-2010, 09:28 PM
If I have a run with some frosted I try to seperate them into lots, seems to me frosted boolits will run a little lighter, a half grain or more. The real bad frosted ones with rounded driving bands get thrown back. I usually get frosted boolits if I cast too many too fast with one mold instead of rotating molds every so many boolits.


05-30-2010, 09:38 PM
Larry, you raise an interesting point.

I've hatched boolits that were the classic product of a disfunctionally hot mould as described herein and elsewhere. It seemed that I worked up to them in the casting progression. Cooled things down and all returned to normal. The frosted ones looked "wrong". They went back into the womb.

Today's exercise yielded boolet after boolit, lovely looking, crying for case, powder and primer. Drop after drop. At low alloy temp. (630)

These were crisp and sharp. I didn't weigh them and I should have. I will in the future.

05-31-2010, 07:43 AM
If you are running your pot at 630 and getting frosting, I'm assuming an aluminum mould, then you have a good casting tempo going. I've seen so many people that pour, wait for the sprue to cool open it and then spend a bunch time looking at the boolits or fiddle farting around. Then they wonder why all their boolits look like prunes! Every second the mould is empty it's cooling. Keep hot alloy in the mould and she gets warmer. I have run 4 cav iron mould hot enough to frost too and that takes some "hurry" sometimes. I still haven't got to that point with a 10 cav H+G!

Anyway, pot temp itself isn't critical IMO. As long as you are getting good fillout at the fill rate tempo you're comfortable with, that's a good temp. If you can't get the wrinkles to stop at that tempo the either cast faster or turn the heat up.

I casted for years, decades actually, without a thermometer. I rarely use one now. I'm not sure what knowing the mould temp will tell you, but I know others have tried it.

05-31-2010, 10:03 AM
With wheelweight alloy, a frosty boolit is a happy boolit. Excellent consistency of size and weight and that is what we "shoot" for, not handsome complexions. This ain't no beauty contest.


05-31-2010, 10:46 AM
I have been casting for a little over two years now and I DO have a 1000 deg thermometer. It was initially used to judge the temperature of the various settings on my pot, as each pot's built=in thermoter will vary immensely. My alloy is 100% WW and there is also a big variation in that also. All wheel weights are not created equally. The main thing I concentrate on is: (1) getting the MOLD TEMP UP, and (2) the consistency of the molded bullets. There will be times when the bullets drop looking just like a mirror and other times when they take on a very frosty look. To me, the color is of no significance as long as the bullets are filled properly. I have had just as much success shooting "frosted" bullets as I have with the "prettiest" bullets you've ever seen.

05-31-2010, 12:55 PM
Thanks, guys. It sounds like I'm making progress. This is month two at casting.

05-31-2010, 01:21 PM
Regarding the use of an infrared thermometer, with the Lee moulds, you can focus the beam on the sprue plate for accurate readings. On iron moulds, I use the same method, but only for uniformity. Measurements on the side or even the bottom of a freshly filled mould can be somewhat lower. Most of us hold a mould upright, and heat rises.

My moulds run around 380 to 400 degrees while at a good casting rate and temperature. I generally cast with the alloy at 700 to 750 degrees, depending on the alloy.

05-31-2010, 01:52 PM
Not to hijack this thread (much)...

454PB - Thanks for some hard data! I think I'll compare temps taken with a screw-in thermocouple and IR readings taken off a sprue plate to see how much they differ. That's the trouble with temperature measurement, it's never the same in all places during dynamic conditions.

Well, temperature is part of why we get frosty bullets, isn't it? Back to main thread...

05-31-2010, 02:28 PM
I was just about to "Thank you" for the numbers, too.

Good info to have and compare.

Hang Fire
05-31-2010, 11:29 PM
Nothing is really wrong with frosted boolits per se, just running alloy a little hot maybe, benefit is they usually have very good fill out. Oh, and they sizzle real good when water dropped.

06-01-2010, 03:15 AM
I'm running alloy @ 630. Something else must account for the frosting.

06-01-2010, 04:24 AM
There seems to be confusion about "Frosty" and "Satin" finish.
If your molds get ENTIRELY toooo hot and you have a substantial tin content you might get truely frosty boolits. This scenario can also cause poor fill or aka shrunken band syndrome.
If you want to really know what frosty is, leave the boolits in the mold and heat the mold with a torch till the alloy melts and let it air cool for about 20-30 minutes. Then you will know what frosty is.

If you have antimony in your alloy and your molds are up to a good operating temperature, you will get a satin finish. This is because the alloy is cooling slower than a cold mold and as antimony cools , it will expand like water to ice. You will actually cast slightly larger boolits and they will have a satin finish because the crystals of antimomy are larger than quick cooled alloy.

If you cast same alloy into a cold mold , the antimony crystals will be realitively small because it is instantly cooled and the boolit will actually age harden exactly the same as water dropped boolits. Usually , bright shiny chrome boolits are slightly smaller than satin boolits when you have antimony in the alloy.

The only thing that the pot temperature effects is how well you get the details filled out and hot quick it heats up your molds. I cast at low temps like you around 630 to 650 because I can make more production by not having sooo long to wait for the spru to solidify and the molds stay cooler.

This is the other thread I was referring earlier

Bass Ackward
06-01-2010, 06:48 AM
You can not frost an alloy that doesn't have antimony and tin in it.

The more tin you have, the lower the temperature you can create that satin look.

Antimony binds to the tin better than the lead which is why tin counters the abrasive nature of antimony. So when you cook away the surface tin, you leave a heavier concentration of abrasive antimony dust behind which is dull in appearance.

Just take a rag and wipe that bullet and the satin look comes right off. You won't be able to tell that slug from a slug molded before the tin cooked.

06-01-2010, 07:14 AM
Well, there's frosty/satin and there's crystallized. The first two are degrees of the same thing. The later is when your mould is way hotter than it should be!

06-01-2010, 07:15 AM
I'm running alloy @ 630. Something else must account for the frosting.

You have a nice hot mould and an alloy with enough tin and antimony to do it. And you casting tempo is fast enough to keep the mould hot. No problem that I can see.

06-01-2010, 09:10 AM
So what's wrong with frosted boolits? Nothing, as long as you have the correct diameter as the bullets drops from the mould.

06-01-2010, 09:21 AM
All new information to me and very helpful in understanding what's going on here. It appears that I stumbled into his condition by accident.

The alloy I've been casting comes from "labeled" boxes of ingots. Just how reliable that labeling is, I cannot say, and I may unknowingly have enriched the Sn and Sb elements in this batch. The result has quite satisfactory though probably unnecessarily heavy on the Pn and Pb for handgun loads.

I dropped a few from a 4-banger 358009 that I recently got from NOE (beautiful machining, BTW), air cooled, and I'll test these for hardness (as they are the only ones from yesterday not slathered with 45/45/10.

Understanding the phenomenon, I can create or eliminate it as needed.

I'm going to start doing more quality control and note taking in my casting.

06-01-2010, 11:09 PM
All new information to me and very helpful in understanding what's going on here. It appears that I stumbled into his condition by accident.

The alloy I've been casting comes from "labeled" boxes of ingots. Just how reliable that labeling is, I cannot say, and I may unknowingly have enriched the Sn and Sb elements in this batch. The result has quite satisfactory though probably unnecessarily heavy on the Pn and Pb for handgun loads.

I dropped a few from a 4-banger 358009 that I recently got from NOE (beautiful machining, BTW), air cooled, and I'll test these for hardness (as they are the only ones from yesterday not slathered with 45/45/10.

Understanding the phenomenon, I can create or eliminate it as needed.

I'm going to start doing more quality control and note taking in my casting.

Pn?; I'll have to look it up to see what it is.


06-01-2010, 11:33 PM
Oops. Got it right the in the first paragraph in which it was mentioned, though.

The text following was written after I had given consent to discontinuing my mother's life support.

I've never cranked out so many boolits in so little time.

It's not been a good day.

06-02-2010, 07:15 AM
Thoughts and prayers to you Wally.