Can you get too much soot on a mold?

[jgh4445]

Got my new Lyman 457125 and 457132 molds in today from BACO. I used hot soapy water and a brush to clean them, dried then and then wiped the cavities out really well with alcohol. Let that dry and began to heat up 10 lbs of 30-1 in my Big Dipper pot. Once everything was up to temp I began casting. The 457125's came out great. They have crisp grease grooves, nice flat bases and are consistently weighing 501 to 503 gr. The diameter is a consistent .457. The 457132 is a whole different case. It weighs from 507 to 511 (I weighed 20-25 ) and the diameter is pretty consistent at 454. Wonder what I did wrong? The 457132 should pour at about .457 and weigh 535. Could I have smoked the cavity too much? I think I did both molds exactly the same. Also, the 457132 was missing the two screws that hold it on to the handles. Had to borrow them from another mold. Not a great start casting a bullet that shot so well in my rifle.

[mpbarry1]

FWIW, I have never smoked a mold. just clean and cast. also, im not sure 4 grains of variation is outside of normal for a bullet that size.

[jgh4445]

I was thinking that with the barrel having been slugged and measuring .458, shooting a .454 would be asking for a leading problem.

[dubber123]

.004" undersize is not going to work well for you. I would re-clean the mold and start again with it very hot. I've never cared for smoking a molds cavities, and yes, it can be overdone.

[Catshooter]

In my tiny little mind, smoking a mould is another of the old wives tales of casting. You know, dipping one corner of the mould into the melt for thirty seconds (that's supposed to be a pre-heat), never sizing a boolit more than .001 over bore size, Marvlux is the way to flux.

All of which I believed prior to coming to this site and getting a real, workable casting education.

So I think any smoking is too much as it just covers up the real problem. Yes it can be too much also. I bought a mould once that must have had fifteen to twenty thousandths of smoking carbon built up in the cavities.

Welcome to the forum.


Cat

[sthwestvictoria]

i would add to the not smoking group. I have been gifted molds that have been smoked and they are horrible, old layers of carbon in the grooves and vents. Ghastly.
A really good scrub with a toothbrush and de-greaser followed by methylated spirits (denatured alcohol) remove the de-greaser then allow to dry and warm on the edge of the pot and start casting.
The Lee manual and information that comes with Lee molds suggests casting however as Catshooter suggests this is old received wisdom and not necessary.

[leftiye]

Just use the mold as clean as you can get it. Do use a bore brush to get into the corners. If you get the mold hot enough it will work fine. It may take a little time (maybe about 50 - 100) casts to "season." Let the oxide be your coating. Blueing a mold helps too. If your climate allows (doesn't cause rust) just put them away after use. This will allow the oxide to cotinue a little. If they do rust in your humidity situation, use a rust preventive oil.

[gtgeorge]

As others have said, no need for smoking a mold. I tried it with the Lee molds early on following intructions etc. and have since cleaned those and never smoked another since . I now have over 30 molds smoke free and of several different brands and materials.

[StrawHat]

...If they do rust in your humidity situation, use a rust preventive oil...

Just make sure you remove all of it prior to casting.

[cbrick]

Could I have smoked the cavity too much?

Absolutely! If you smoked the mold you smoked it too much.

Think about what you did, you took the time, effort and cleaned the mold well and even used alcohol and then the very first thing you did was gunk it up.

The very best casting mold is a perfectly clean mold.

The very best smoking a mold could do if it helps at all in casting is to cover up a problem. It's far better if there is a problem to find it and correct it.

Some old wives tales will probably never die, this is certainly one of them.

Rick

[JSnover]

I gave up smoking mine. There is no valid reason to do this, IMO.
In the early days I got the same weight/size variations and thought they were ok since it was only about 1%. You can easily cut that in half by casting at a higher speed. If the boolits are well filled and the surfaces are clean, try to make sure you're not letting the mold cool between pours.

[Czech_too]

The 457132 is a new mould? Could it be that it's undersized and this would account for the dia. & weight difference? Just a thought.

[jgh4445]

Thanks guys. The molds are now pristine clean...all of the boolits are being re-melted. We'll try again an see what happens. By the way, there was a whole bunch of soot in the mold in question. Maybe it was enough to cause the boolits to drop .003 under size.

[plainsman456]

Yep,no smoking molds for me.

makes no sense to clean them then put more clabber in.

[jgh4445]

You guys nailed it! Cleaned the molds really well and started casting. BTW, I've always used a 4 lb bottom dripper to cast with. This is my first experience with a ladle. What I've learned:

Don't smoke it.
Get it clean!
Get it clean some more.
Get it hot!
Don't pour slowly or dribble with a ladle. Set the ladle in the sprue hole with the mold turned sideways, turn it up and let it dump.

The mold that was pouring .457 @ 501 to 503 is now pouring 458-59 @ 505-509.
The mold that was pouring .454 @ 507-511 is now pouring .458 - 460 @ 520 - 525.
What a difference!

[dubber123]

Awesome! I'm glad you made such a big leap forward. I have to try ladle casting at some point.

[ipijohn]

Any smoke on a mold is too much for me.

[quilbilly]

As someone who has been casting fishing jigs commercially for 30+ years and boolits for myself, I very lightly smoke any of my molds one time when I first get them and rarely do it again. The molds seem to produce a better product that way but I have never figured out why it is not needed again.

[JSnover]

I was advised to smoke new molds in order to make them drop easier. I think all it did was mask the break-in period. My new, un-smoked molds worked as well and took about the same amount of time to start producing (and releasing) good clean boolits.
Temperature and tempo...

[Wayne Smith]

Yes, with those big boolits pressure casting is often the ticket. Your mold, like my 457122, could probably be slightly better vented, but I don't mine pressure casting and it works!