Does this sound like a zinc contaminated ingot to you? or just zincophobia?

[mikeystew]

i've been casting ingots for a couple days now, but today i moved up to a larger setup to melt more lead at once. im now using a 73000 btu cooker set to medium and a metal 5 gallon pail. i loaded about 35# of clip on WW and as soon as it went molten i skimmed off the clips and steel/zinc weights, then a couple minuites later once the temp came up a bit higher i dropped in a piece of wax and stirred/scraped.

but when i skimmed off the dross, to my surprise i pulled out a steel clip... i dont know how i missed it, and have no way of knowing if it was from a lead weight or a melted zinc one, but when i poured the muffin molds the ingots came out with a significant ammount of bubbles on the base of the ingots.

the mold has been used for several days without this issue, so does this sound like zinc contamination or something of lesser concern? due to me using a larger setup i don't know if it could be related to temperature or what. i was also water quenching the molds on a cookie sheet to allow for a quicker release from the mold if that would have any affect.

any info/opinions would be greatly appreciated.
Mike

[jsizemore]

It's not unusual for a random clip to rise to the surface when fluxing the melt. Might try a thermometer to let you know what your temp is.

[GP100man]

Zinc is liter than lead it`ll float , I think a painted clip mite have stuck to the bottom then came loose when stired .

I`ve had it to happen also but in this era of zinc & steel ??????

Ya gotta get over 2-3% zinc to really notice a difference in castability.

[mikeystew]

OK, i submerged a puck into 50/50 muriatic acid and water and it did nothing after 10 min. but i also put a drop of pure acid on the ingot and after a few minuites it started to bubble very lightly and darkened the spot. could that not be caused by the antimony?

[shotman]

the bubbles is from the cold mold the acid will confirm zinc . That will not hurt you for cast boolits but dont use it in a shotmaker

[GP100man]

But who checks for zinc at the WW factory ????

Could`ve been traces from the start ??

Your thoughts????

This has always been in the back of my mind !!

[sagacious]

...but when i poured the muffin molds the ingots came out with a significant ammount of bubbles on the base of the ingots.

the mold has been used for several days without this issue, so does this sound like zinc contamination or something of lesser concern?

'Bubbles' on the underside of an ingot is not a symptom of zinc contamination itself. It's a sign that there was minute amounts of water present on the ingot mold. This is common.

Preheating the ingot molds to about 200-250*F removes any trace of water, and can avoid unexpected splatters. Good luck.

[mikeystew]

does anyone know for sure if a decent alloy will bubble lightly after several minuites of applying acid to it? because it wasn't much of a reaction. honestly i think im in the clear because i tried to sort the weights as best as i could beforehand, and if it was a zinc weight that melted it was only one out of a couple hundred in that melt because i skimmed it immediately after it became molten.

also i can see the water in the mold scenario being true in this case as i was quenching the molds in a cookie sheet. lots of steam about. the part thats killing me is that i don't have my mold yet that i ordered a few weeks ago from Swede. when it comes in i'll know for sure if i have a problem i guess. till then... game on, fire up the pot!

[sagacious]

Does sorta sound a little like zincophobia... :) Don't sweat it. A stray ww clip floating in the melt, and some moisture bubbles on the ingots is no cause for concern. Keep on keepin'-on, and you'll be fine. Good luck.

[tophet1]

mikeystew,

I'm at exactly the same stage of learning as you are. I finally have handles for my mold and will be casting for the first time this afternoon.

I have also worried about everything, but untill I start pouring into the mold, it is all theory. (I've been told while casting to play the soundtrack of the movie Zulu and hold my tongue to the left. I beleive this helps). Lol

[Charlie Two Tracks]

I didn't know about the holding your tongue to the left, thing. Maybe it will work soother next time.

[sljacob]

But who checks for zinc at the WW factory ????

Could`ve been traces from the start ??

Your thoughts????

This has always been in the back of my mind !!

wow one more thing to worry about:groner:

[Wayne Smith]

NAAH! "Traces" of zinc are no issue. I'm not sure at what point it does become an issue, and I'm sure Felix will chime in here at some point and give us a precise % at which it does interfere. Generally, my guess is that if I'm melting 100lbs of ww and get one zinc weight in I've got nothing to worry about.

Bubbles in ingots - happens all the time around here when the humidity gets up!

[mikeystew]

i made some more this morning, this time i skimmed the clips etc, added more weights, stir constantly, repeat. i kept the heat as low as possible until it went molten before skimming and had about 50lbs in the pot before i fluxed. this time i also used a lot moe wax in the flux, about 1/4oz i figure, and i let it flux for probably 7 - 8 min stirring and scraping constantly until it looked clean, all the while heating the pans by leaning them on the melting pot.

Well well, these things are SMOOTH! i've made some real beauties here. and after water quenching and billows of steam rising from around the pans, my next series of ingots had the bubbles from the excess moisture in the area.

i went back to heating the molds for a minuite before each pour and got consistantly smooth shiny ingots every time. Thanks for the insight guys, im learning.