Bad fill-out

[ErikT]

Howdy! I've been having trouble with fill-out in some of my moulds lately, and I'm new enough to casting that I'm having trouble narrowing down the cause. I've been casting with WW alloy, and I keep getting bad fill-out and wrinkled boolits. I flux regularly during casting, and I always ensure that my pot and alloy are clean. I check every WW that goes into the pot by cuttinginto it with a pair of side-cutters. The lead ones are easy, the zinc ones are almost like iron, but I just don't know for sure if I'm catching them all.
The wrinkles happen regardless of mould and alloy temperature, though it seems to get a little better when my pot is screaming hot and the boolits are frosted badly. Is it possible that I have some zinc contamination in there, or maybe I just need more tin? I've degreased the heck out of the moulds several times, so I don't think it's caused by contaminants in the moulds themselves.
I should add that this happens with aluminium and iron moulds, both custom (NOE) and commercially produced (Lee, Lyman, RCBS).
I'm really getting frustrated with this problem. My reject rate for boolits is around 80%, and to me that's unacceptable.

[larryy]

The only way to test for sure is to get a known clean alloy, clean out your pot and try casting with that. If your bullets come out good you know it is your mix. Plumbers are a source for lead, and solder will get you tin. Even a pound of lead will tell you if you are on the right track.

[Defcon-One]

In my experience wrinkles mean oil in the mold!

Pick one mold, clean it well, dry it thoroughly and try again with the same alloy. I clean mine with a soft tooth brush, mild dish soap (Palmolive) and hot water, twice, then rinse again and dry with a cotton towel. Then air dry. I have had trouble with chemical degreasers leaving films that cause these same problems.

If that does not work, I'd add 2% Tin to the mix and try again. Once you get one mold working, cast a batch, then move on to the next mold.

I doubt it is Zinc, because you can usually see that in the metal as Oatmeal like clumps, but if your worried, just keep the smelting temp around 700 degrees F. Zinc won't melt at that low temp but all the lead WW will. I cast around 750 degrees F, still below the melting point of pure Zinc.

[Gtek]

1- Did you know temp when melting WW down?
2- Was it really hot and you kept cleaning all that gray krinkly stuff off top?
3- What temp was your pot when casting?
4- Ladle or bottom drop?
5- Boolit diameter / weight being cast?
6- # of holes in mold?
Easy way first- couple pounds of another source of lead, confirm pot 650 to 725 and try again.
Report back with findings, be constant, take notes. Be Safe- Gtek

[a.squibload]

What they said, also:
Something I learned here on CB, lead temp and mold temp are different animals.
Preheat your mold on an electric "hotplate", or dip the corner in the melt with mold closed.
Can also dip the sprue plate handle, it wants to be hot too.
Keep moving to keep the mold hot.
Pour, sprue solidifies (or almost solidifies), cut sprue, dump boolits, close mold, pour...
check boolits after you get a pile.

A little tin goes a long way, that also helps.

[ErikT]

Thanks for the advice, guys! I now have a few more things to try. I have tried degreasing the moulds with dish soap and a toothbrush as well as some commercial degreasers, but maybe I'm just not being thorough enough. I will degrease them to within an inch of their lives before I try again!
I will also definitely clean out the pot and use some pure lead to see if it's my alloy. If I do have some contamination, then I'll have to try and purify it using one of the methods on this board; sulphur or sawdust. I've been very careful about checking each WW that goes into the pot; I don't see how a zinc one could have gotten in there. Like I mentioned, I clip each WW with a pair of side cutters, and to my knowledge the zinc ones are much, much harder, aren't they?
I will try casting a bunch this next week, if possible, and I will see what results I get. Thanks a bunch!

[zomby woof]

Lightly prep the mold with a butane lighter, start casting better boolits.

Have you tried this?

[P.K.]

Lightly prep the mold with a butane lighter, start casting better boolits.

Have you tried this?

Yup, carbon in the boolit cavities deffinatley helps. Also as stated temp an mold cleanliness are a must. I use acetone( nail polish remover) on a q-tip to clean the surfaces of mine before pouring my first run on a new mold.

[fishnbob]

Thanks for the advice, guys! I've been very careful about checking each WW that goes into the pot; I don't see how a zinc one could have gotten in there. Like I mentioned, I clip each WW with a pair of side cutters, and to my knowledge the zinc ones are much, much harder, aren't they?
I will try casting a bunch this next week, if possible, and I will see what results I get. Thanks a bunch!

Are you smelting your WW's in a separate pot and fluxing & cleaning your alloy and pouring into ingots to later be introduced into your casting pot as clean ingots? If you are putting WW's into your caster, the trash not fluxed out will find your bottom pour spout and make casting difficult. You need to keep your casting pot clean. If frosty boolits come out wrinkle free, your mold is not hot enough and it may be a very fine line between wrinkled boolits and frosty ones. Every mold I have is different and has to be handled differently and I have to remember which one likes to be stroked differently. Reminds me of women. There is also the issue of oxidation and I do better when I keep a coat of fluxed material on top of the alloy and for some reason the boolits get better when I get down to the bottom of the pot. Maybe a drop in pressure due to the alloy weight pressing downward? My personal advice is to visit the Stickies and cipher through that. A ton of info there as well as Glen Fryxell's writings on casting found referenced here in the volumes of posts. Good Luck

[wiljen]

Clean the mold, boil in hot water to remove traces of cleaner, get it hot enough and really flux your alloy. One of those things cures the problem about 98% of the time.

[cbrick]

The wrinkles happen regardless of mould and alloy temperature, though it seems to get a little better when my pot is screaming hot and the boolits are frosted badly. maybe I just need more tin?

Since you say you've cleaned the molds well and have been cautious of zinc with the WW these are probably not the cause.

A screaming hot pot and you have much less tin in your alloy and the tin that may remain cannot do what it is in the alloy to do. Starting about 750 degrees and up tin looses it's ability to reduce surface tension of the alloy going into your mold and that is the reason for having it in the alloy. Starting at about 750 degrees tin itself oxidizes very rapidly, adding more tin will be a waste of money, time and effort with high pot temps.

Your problem sounds very much like you are not casting fast enough with a properly pre-heated mold. A pot (alloy) temp of no more than 725 degrees is more than enough heat to get and keep your mold at a proper casting temp of somewhere under 500 degrees (mold types vary on exact heat, Alum, brass ect).

Stop inspecting your bullets while casting, plenty of time for that once you've finished. Once the sprue freezes open the sprue, dump bullet and close the blocks, re-fill as soon as possible. Keep the blocks closed and out of the air as much as possible. keep the rythm and pace up, you'll never get good bullet from a mold that is too cool.

Rick

[williamwaco]

The only thing I can add to what has already been said is:

Zinc is not your problem. I isolate zinc contaminated metal when I discover it. when I get ten or 12 pounds I pop it into the pot. flux it three or four times with sawdust ( wax will not work ) and cast pistol bullets with it. They work fine for me.

Wrinkled bullets can be caused by oil. They can also be caused by cool mold or cool alloy ( those are not the same thing ). They can also be caused by pouring the metal too fast or with too much force causing it to splash in the cavity.

I have also discovered that some molds regardless of number of times cleaned and number of bullets dropped for a break-in period, or temperature, or how the alloy is poured just will not drop unwrinkled bullets. Fortunately these molds are rare. Smoking will help these molds. Smoke lightly first. Too much smoke can reduce the diameter of the bullet. I use a butane firestarter for smoking.