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Dross, Flux, and Alloys  Rating:  Rating
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 Posted: Thu Oct 15th, 2009 11:48 am
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Gene
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I attempted to cast my first bullets today and out of about 40, one was possibly good enough to keep !!!!
The dross is the black crude that comes up, right ???  There is a medium gray substance that appears on the top, is that the tin and antimony ??? 

 I am using a small butane camp stove to heat with.  It's probably not getting the mix hot enough, right ???  When I put my ingots in the pot, they melted in less than 10 mins !!!!


Please advise.

Thanks in advance,
Gene

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 Posted: Thu Oct 15th, 2009 11:57 am
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KenK
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Persevere,  I've been casting many years and it takes me more than 40 culls to get good bullets going sometimes.

Use some candle wax or parrafin to flux with.  If it catchs on fire the melt is hot enough.  Skim the crap on top off.

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 Posted: Thu Oct 15th, 2009 12:24 pm
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Gene
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I fluxed with wax and most of the time it ignited on it's own.  Is the med. gray powdery substance that comes to the top is that dross or some of the alloys not getting hot enough to melt ???  The more I stir, the more comes to the top..... I don't want to skim off my tin or antimony...

 

Thanks,

Gene

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 Posted: Thu Oct 15th, 2009 01:17 pm
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Dollar Bill
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Gene,

When you flux, you have to stir vigorously. As the crap comes out of the alloy, it tends to stick to the sides and bottom of the pot. With my Lee bottom-pour pots. it also sticks to the rod. I think that will help.

I've read various learned dissertations on what exactly is coming to the top, as far as tin and antimony, and from what I've gathered, it's oxides of those materials, and one gentleman, who's a commercial caster, stated that, using pure alloys (not wheel weights) that he doesn't even flux when the dross forms, and his bullets hardness check correctly. So don't get to worried about tin and antimony loss. Make sure your alloy is clean (I flux vigorously twice initially), make sure your mould is hot enough and cast away. Like Ken said, sometimes it takes quite a few bullets thru the mould to get it going good.



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Bill
“Those who sacrifice Liberty for security deserve neither” -Benjamin Franklin
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 Posted: Fri Oct 16th, 2009 09:02 am
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Jeff Bowles
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That gray powdery substance is a combination of the ash remaining from the wax and oxidized lead, tin and/or antimony.
You will not loose much tin or antimony when fluxing, most is lead with oxidizes at a much lower temperature.
Get an old coffee can and chuck your dross skimmings into that, the next time you batch up some alloy, add that to it and flux after melting. If there is any lead, tin or antimony in the dross, it will get blended into the new batch and not wasted.
I dont flux a lot when making pistol bullets which are a lower brinell than say the bullets I make for competition in my bench guns.
I do flux 2 times before I start casting with any alloy. If you are getting crap that comes to the top, you havent fluxed enough.
I cast at 800 degrees and I use a hot plate to prewarm the molds, but still I have several culls before I get good bullets. If breaking in a new mold, sometimes quite a few more culls.
Make sure you mold is clean and grease free before you start. Make sure you follow the makers instructions for lubricating them. If it is an aluminum mold, use a sprue plate lube, either BullPlate from the BullShop in Delta Junction, AK or Rapine mold prep. I use both, I use Rapine on the Aluminum molds and BullPlate of the cast iron ones. No reason, it is just what works best for me.

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 Posted: Fri Oct 16th, 2009 09:11 am
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Stephen Perry
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Gene

Ken and Bill are telling you what happens in ptrpating the pot to get reasdy to Cast and their experience is the same as mine and others.

What I can add to this is speed in casting. You have to get a mold to a proper temp and keep it that way. Fast is good in casting but sloppy is not good. You will see where your at when all your bullets come out with filled cavities and your sample cast weights are a tenth or rwo.

Stephen Perry

Angeles BR:fire

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 Posted: Sat Oct 17th, 2009 09:02 pm
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Gene
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Cast about 150 rds today.  Wts varied from 151 to 157. I'm pretty sure the med gray substance is unmelted lead.  IMHO my little butane stove is not getting the mix hot enough to thoroughly mix the metals.  Most of the bullets look great, but the size seems to be too large  .359 to .361.  I'll probably have to resize, rats...............

My uncle let me borrow his Coleman propane stove to try.  The flame was larger and hotter, but the grill held my pot too high to take advantage of it..............

Sidebar:  the WW's you get now are 40% zinc !!!!!

 

Thanks,

Gene

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 Posted: Sat Oct 17th, 2009 10:43 pm
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KenK
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Are you casting outside?

It was cold and windy here in Georgia today, probably more so in NC.  A cold breeze or just a good draft blowing across the top of the pot will oxidize the metal quickly. 

The old white gas Coleman will get plenty hot enough, I don't know about the propane ones.

A $50 Lee electric pot is the way to go if it's in the budget.

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 Posted: Sun Oct 18th, 2009 12:02 am
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chboats
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Gene
I think what your are seeing as a gray film on to top of the melt is oxidized metal, as the others have said, not unmelted lead. If it was unmelted metal it would probably be lumpy. Even the cleanest of metals will form a dull gray film on the top. The hotter it gets the quicker it will form. If your flux ignites on it own the melt is probably hot enough. I have had new molds that no matter how they were cleaned they might take what seemed like a lot of casts before they started dropping good bullets.

I also have a couple of Aluminum molds that must be squizzed very tight to get consistent diameters. I have not had that problem with iron molds

Stick with it, once you figure out what works for you your big worry will be where to get more lead.
Carl

Last edited on Sun Oct 18th, 2009 12:10 am by chboats

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 Posted: Fri Nov 6th, 2009 09:56 am
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Dicko
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Hi Gene,

There's not enough info in your message to figure out what your problem is exactly.  There can be a million reasons for poor bullets.   But since you have raised the issue of drossing let's tackle that.    Some things can't be explained in a few words so forgive me if this is a bit long.   Some books tell you that regular fluxing is necessary to prevent the tin and antimony from separating and floating to the top.   That is untrue because once in solution with lead, both tin and antimony will remain so and can be separated only by sophisticated methods available only to laboratories and foundries. 

Fluxing is for cleaning out dirt and dross, that's all.   Dirt and dross are not quite the same thing but have the same effect and are removed together so can be discussed together.   Dirt is what's on or in the lead before melting.   Dross is created by oxidation of the alloy by temperature, mostly the tin, which is why a perfectly clean alloy will accumulate some dross over time.

Oxidation or drossing is temperature related.  At 750F it isn't much.   Above that it becomes increasingly perceptible until at 900F most of the tin in a 5% tin/lead alloy will dross off in 30 minutes.   I have had the experience of a heavy blue/brown flaky dross precipitation from the melt in a Lee 10 lb pot at max setting in 30 minutes.  A thermometer showed that to be over 900F which is also in the danger zone for fumes.   Drossing is mostly caused by casting too hot.   At 600F I can cast continuously for several days before needing to flux. 

There is no need for Marvelux or other fancy fluxes that don't do a better job than ordinary candle wax.   The foundries don't use them.   They use a cheap but effective method called "dry drossing" with sawdust and caustic soda.   Don't try it, it can be dangerous and needs experience.

How to recognise when to flux ?  Not difficult, the amount of sludge on the top of the melt tells you.   Over time the dross builds up until it looks, and feels when stirred, like a thick sludge.   A sure way to identify it is to rake off a ladle full, let it partially solidify and dump it on the floor.  There's no mistaking the difference between clean alloy and sludgy dross.   But that shouldn't be necessary, a little experience will soon tell you when to flux.   

You need to vigorously stir a new batch of alloy to make the dirt float to the top, but you don't actually have to flux again after that.  You can get rid of dross by simply skimming off the sludge.   But that sludge is made up of particles of dross entrapped in the alloy.   Fluxing separates them and you save the alloy.     

I do it this way.   Drop a one inch piece of a cheap candle into the melt and stir it in.  You want it to flame.   If it doesn't drop in another piece.  That usually does the trick.   Some books say it is best not to flame, but I found flaming works best.   Wear a welding glove to protect your hand from the flames while stirring.   It looks like a small but vigorous fire and gives off a lot of smoke.   It will burn for four or five minutes, and will leave a pile of fine ash on top of the melt which you skim off.

If the first burn does not produce full separation do it again.  If it is done properly the top of the melt should be free of sludge and be clean and shiny.

Give it a try and tell us what happens.   If you are still having trouble we can talk about mould preparation, alloy mix, melting temperature etc.

 

 

 

 

 

 

 

 

 

 

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 Posted: Fri Nov 6th, 2009 11:39 am
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Gene
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Dicko,

Thanks..................I've broken down and bought a Lee electric melter.  I'm going to crank it up this weekend and give casting another try.

If I get the hang of it, then Ill need a good 38, 44, and 30 cal. moulds.

Gene

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 Posted: Sat Nov 7th, 2009 02:16 am
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Dicko
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Hi Gene,

I have a proposition for you.   Let me say at the outset that it is self serving to an extent but it might work for you.   I suppose it also constitutes advertising so I hope the moderator won't mind if it is to the general benefit.   I recently completed a book on bullet casting with two more partly written.   Why three ?   The completed book is for beginners, but is still much more detailed than anything yet published, 45 pages of A4 ( similar to 8.50 x 11 inch ) with 65 photos.   The second book is much bigger, is aimed at big volume casting and the equipment and techniques needed for that.   The third is specifically about cast rifle bullets and will contain velocity readings and chamber pressure test results.   The last two are some way to go and could be a couple of years still.   But the beginners book is complete.   It is intended as an E book for internet sale.   I need a beginner to test it on, so I will send it to you free of charge if you are interested.   It answers all the questions you have asked thus far and everything you need to know to cast top quality bullets.  I will ask the moderator to send you my e mail address so we can discuss it privately if you are interested.

 

 

 

 

 

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 Posted: Sat Nov 7th, 2009 02:49 am
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Dicko
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Hi Gene,

6 grain variance in bullet weight says something is badly wrong.   Shouldn't be more than half a grain or at most one grain allowing for the possibility of bigger than usual variance between cavities.   6 grains suggests incomplete fill out and not just a little, a lot, that should be obvious by visual inspection.   It suggests alloy temperature too cool, but I'd need more info to say for sure.

I consider a thermometer essential.   Lee electric pots are thermostat controlled but tell you what the temp actually is.   I recommend one of those thermometers from RCBS or Lyman, and similar thermometers are available from suppliers of such equipment that will be found in every city.

 

 

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 Posted: Sat Nov 7th, 2009 07:06 am
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Gene
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Dicko,

Yes, I'll give it a try.  There's a lot of satisfaction derived from shooting your own bullets.

Thanks,

Gene

pearcottage@triad.rr.com

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