Author Topic: Smoked Cavity Blow out  (Read 5947 times)

Offline Partycrasher

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Smoked Cavity Blow out
« on: 08/31/15 11:07 UTC »
I had just smoked a cavity because the collar wasn't filling properly.  Poured some lead in it and it blew out.  I found lead beads and strings on the floor 15' away.  Most of the "burp" hit my hand.

I wear welders gloves 90% of the time and have been doing this 39 years and never had this happen.  I'll be wearing gloves 100% of the time now. 

But what from the smoking process could have caused moisture?  Puzzled!


Offline Bucko

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Re: Smoked Cavity Blow out
« Reply #1 on: 08/31/15 11:49 UTC »
Heavy carbon can attract moisture from the air.   I don't blacken any molds.   Neighbor is a chemist and we were talking about this one day when he came over to get some jigs.  I had a used mold I bought that was blackened and was trying to clean it out.   I have no proof of this myself and just going by what he told me.

Online Muskygary

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Re: Smoked Cavity Blow out
« Reply #2 on: 08/31/15 12:38 UTC »
I spray my molds with drop out. One day I was in a hurry, I thought the mold was dry. Started to pour lead in it  and bam ! Lead flying out the top of the mold, learned my lesson well. Be careful.

Online ctom

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Re: Smoked Cavity Blow out
« Reply #3 on: 08/31/15 12:40 UTC »
Gotta not feel too good. I second the moisture in carbon theory. I don't smoke lead molds and have never had a problem with any that I have or have used.

Offline Partycrasher

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Re: Smoked Cavity Blow out
« Reply #4 on: 08/31/15 13:37 UTC »
I had to peel off the lead/skin.  That hurt!!!  Its pretty good today.  Just have to keep it clean now.  The spots that hurt now are the blistered areas above the burned area in the photo. 

I've had smoked cavities crackle a little but never anything like this.  It was raining and probably 100% humidity that day.  I was in the garage but it was VERY humid.

Interestingly, that jig that caused the burp is hollow. 

Offline Walking Dead

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Re: Smoked Cavity Blow out
« Reply #5 on: 08/31/15 13:46 UTC »
This has a guy double thinking about pouring lead.

Offline Apdriver

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Re: Smoked Cavity Blow out
« Reply #6 on: 08/31/15 15:07 UTC »
I use FArsenal drop out, also. Never had a mold even sizzle. This just shows, you can't be too careful. Gloves, eye protection, and long sleeves, pants and shoes at a minimum.

Offline Bucko

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Re: Smoked Cavity Blow out
« Reply #7 on: 08/31/15 15:33 UTC »
The jig is hollow because it blew out.   Kinda like a popcorn kernel has that little bit of moisture in it that boils then makes the kernel burst.   It's the same effect.

Offline Walking Dead

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Re: Smoked Cavity Blow out
« Reply #8 on: 08/31/15 18:29 UTC »
So if I am understanding this, the cavity had moisture, the hot lead was dropped into the cavity and the expected explosion took place blowing molten lead out the top and thus the disaster.

Any other pointers to prevent this blow out?

I figured heating the mold over the lead would take the condensation issue out of the equation.

Offline Bucko

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Re: Smoked Cavity Blow out
« Reply #9 on: 08/31/15 19:15 UTC »
Heating is a good option as it will make it pour easier too.   I always inspect them before using for any moisture.   I simply open the mold partially and rest it in top of my pot while the lead heats up.   

Offline Apdriver

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Re: Smoked Cavity Blow out
« Reply #10 on: 08/31/15 20:48 UTC »
That's one thing I didn't think about. I always heat my molds. This is one very explosive reason to do so. PartyCrasher, glad you're OK with just a burn.

Offline Partycrasher

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Re: Smoked Cavity Blow out
« Reply #11 on: 09/01/15 14:05 UTC »
Thanks for all the input.  I will certainly never cut corners and not wear both gloves ever again. 

Walking Dead, don't let this deter you.  I've been pouring 39 years and this is the first freak accident I have ever had.

Ventilate the area, wear good heavy gloves, and don't cut corners on safety and you will be fine.

Marc

Offline Bucko

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Re: Smoked Cavity Blow out
« Reply #12 on: 09/01/15 17:12 UTC »
Since it is nearly impossible to place hooks and inserts while wearing welding gloves this is what I do.   I use my right hand (because my left is not smart sometimes) to place hooks and whatnot.   Kinda clunky to take the glove on and off a couple hundred times and it makes pouring slower.   So...  I put on a 3x3 patch of Velcro on the underside wrist portion of my glove and the other half is stuck onto the table.   That way you can use the table as a third hand to slip your glove on and off very quickly and seamlessly.   That way I never have to set my mold down and I can remain on a continuous flowing motion that results in a more productive pouring session.

Offline Justin9j

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Re: Smoked Cavity Blow out
« Reply #13 on: 09/01/15 19:04 UTC »
Buck that's a pretty good routine.

Offline Partycrasher

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Re: Smoked Cavity Blow out
« Reply #14 on: 09/02/15 13:12 UTC »
Great idea!  Thanks,

Marc