Sticky Aluminum Mold

[ChristopherO]

Have piggy back on Joatmon's "Mold Prep" thread. I've used steal and aluminum molds before but this new aluminum mold is tricky. I've heat cycled it multiple times now, and cast at least 300 boolits with the majority tossed back in the pot, but two issues keep popping up: 1) one of the two cavity bases don't quite fill out (1 PB, 1 GC), could be either depending on the pour, and 2) one of the cavities hold the boolit tight and not releasing (Normally the PB cavity is worse, though that can switch on occasion). This morning I began pouring into the GC cavity only to have success.

This is using the Lee 20 Lb pot and ladle pouring a hot stream set on high.

I cleaned as recommended with dawn and a tooth brush as per NOE's instructions. Smoked both cavities with soot from matches and yet these problems persist.

One more item that I notice, too, is the sprue holes have a little lip at the bottom where the lead flows into the cavity. This causes lead boogers to form in the hole. I've had this with other molds, but this raised lip is more pronounced than realized with the other molds in my stash. This is a well made mold, I just need to get the full potential from it.
Thanks,
ChristopherO

[Mwilson0173]

I have same problems and going to follow this post.

[Winger Ed.]

If everything else is good--- temp. maybe smoking the mold, etc.:

Cool, cast Lead doesn't like burrs in the mold.
It wants to hang onto them like a cat climbing up on a screen door.

I've had a issue once in awhile of a boolit sticking to one side of the mold.
Without getting violent, sometimes rubbing the inside edge of that block a few times on my blue jeans leg will cure it.

[Bazoo]

I’ve helped a sticky mould by tracing the edge of the cavities firmly with a pencil. I’ve also used a bronze toothbrush, pulled from the cavity towards the block faces. It may very slightly round the edge and show the part line. The ones I’ve done, I did slightly and it just showed the part line but didn’t make it raised.

[uscra112]

Inadequate fillout in one cavity is usually caused by the mould and especially the cutoff plate not being hot enough. One reason I don't use a bottom-pour pot anymore is that it's a pain to spill enough molten lead over the cutoff plate to keep it hot, and to fill the dimples in the plate. Not filling the dimples is probably why you're getting those "boogers".

I can't say I've ever had a mould with a burr on the cavity edge. New moulds are CNC machined with the blocks fully closed; it would be well-nigh impossible to create one. An old cherried mould, yes.

I've never once "heat cycled" a new aluminum mould. Just wash it out with Brakleen and start casting. If I preheat the mould, the third or fourth bullet will be good. As will every subsequent one unless I break my rhythm, thus letting the mould cool down.

[ChristopherO]

Thanks men, for all the responses. I'll try the pencil trick, rubbing the cavities over my jeans and maybe look for a bronze toothbrush. I may have bronze cleaning brushes in the kit.

I'll post a fuller reply to the last post, to help reveal a bit more of what I am doing:


Inadequate fillout in one cavity is usually caused by the mould and especially the cutoff plate not being hot enough. One reason I don't use a bottom-pour pot anymore is that it's a pain to spill enough molten lead over the cutoff plate to keep it hot, and to fill the dimples in the plate. Not filling the dimples is probably why you're getting those "boogers". The sprue plate dimples are not only full but with a nice bubble of liquid lead on top to fully harden before cutting off the sprue. The lead is so hot (highest setting on the pot) that it takes about 10 seconds for the sprue to fully crinkle up and change color, indicating it is finally solid. Still, on or the other cavity will many times not have a perfect base to the boolit, but a ever so slightly rounded base. On the PB side this won't do. On the GC side the rest of the boolit is perfect and I will let the GC take care of that base, for better or for worse.

I can't say I've ever had a mould with a burr on the cavity edge. New moulds are CNC machined with the blocks fully closed; it would be well-nigh impossible to create one. An old cherried mould, yes. I don't know if the cavity edge has a burr, the bottom edge of the sprue hole has a slightly raised edge, though, holding the boogers, possibly impeding the pour?

I've never once "heat cycled" a new aluminum mould. Just wash it out with Brakleen and start casting. If I preheat the mould, the third or fourth bullet will be good. As will every subsequent one unless I break my rhythm, thus letting the mould cool down. I agree, that is what I normally experience with a new mold, aluminum or steel. Unfortunately this one is being a stickler.

I'll post the improvements when I can get back to this mold with your tips.
Cheers

[GregLaROCHE]

Unfortunately, I’ve found that some molds are just sticky, no matter what you do or how many times you cast with them. Maybe it’s the machining?
As for the bases, make sure the sprue plate is perfectly flat. Rub it on a new sharpening stone or a known flat surface with wet and dry sandpaper, to see if there are irregularities. Make sure the sprue plate is tightened down properly. Finally make sure your sprue is big enough before you stop pouring.

[GhostHawk]

As a last resort, rather than dispose or dispence with the mold. You may want to try something radical.
Spend 8-10$ on a bottle of "Liquid Wrench Dry Lubricant"

I apply mine with a cheap cotton q-tip. 2 drops on the q-tip, work the mold cavitys, then the rest of the mold. Sprue plate, holes, etc. Watch for little threads of cotton on the edges of the cavity's indicating a burr. If you find some I would use a hard wood to polish them out. Artist small paint brush handle works well.


LWDL goes on wet, evaporates, leaves a dry film. Treat a mold, set it on top of the pot to warm. By the time its warm if you did it like I described there remains zero liquid to migrate. Start pouring.

Bullets should fall out.

Most molds I am good for thousands of boolits before needing a retreatment.
Problem molds could be lower, 500 to a thousand. When bullets start sticking, quit, cool it down and retreat.

This single 4 0z bottle will last me all of my life and still have half left.

No more beat up, beat to heck molds. No more lead wanting to stick to sprue plates.

This stuff is good.


It appears no one is carrying the 4oz bottles, have to buy an 11 oz spray. Should still do the trick.

[ChristopherO]

Taking the mold apart, into the halves I smoothed the cavity edges by passing the mold face over a pad of Scotchbrite. After this, while running a pencil lead over the cavity edges, as recommended by Bazoo, is when I noticed that one half of the PB portion had chatter marks on the meplat edge. Not only was there chatter marks but the edge of that side of the cavity was raised slightly along the top of the nose. Carefully removing that raised edge with the blade of a utility knife was instrumental in allowing the two halves to match up equally on the meplat.
Using the Scotchbrite on the bottom surface of the sprue plate assured that it was slick and smooth, also. With the mold off the handles, in two halves, allowed the matches to smoke the cavities much more uniformly than when I was trying to hold it in various configurations previously. Once fastened back on the handles the alignment pins were lubricated again, as well at the sprue plate pivot point.
By this time the pot was up to temperature and ready to reassess the mold prep's adequacy. Once the mold was hot enough, which didn't take long, the castings were coming out much better than previously. I won't go as far to say there were falling out on their own, but both cavities were, with required raps on the handle hinge, releasing their contents with much more satisfactory results. The better smoking of the cavities and taking that slight edge off the nose did make a considerable difference, especially on the Plain Base cavity. I had to throw some back into the melt, but the percentage was far less than before. If I can keep the mold closed longer, retaining the heat, without spending too much time trying to free the Boolits from the cavities, that makes the process go much smoother.
Thank you all for your suggestions. I'll continue to keep them in mind as I work to get the best this mold can offer.
ChristopherO

[GregLaROCHE]

Glad you pretty much solved your problem. Most likely the mold will get better with time. How are those bases now?

[ChristopherO]

Glad you pretty much solved your problem. Most likely the mold will get better with time. How are those bases now?

Bases are better, mainly because I don't have the mold open so long trying to pop the cast out of them now. I still keep more of the GC boolits than the PB, due to the bases. The rest of the boolit can be perfect, but if there is any place that isn't fully filled out it will be a base every so many pours. I believe you are correct, the mold will line out with continued use.

[gwpercle]

And don't forget ... You got to hold your mouth right when casting !

[ChristopherO]

And don't forget ... You got to hold your mouth right when casting !

Ain't it the Truth!

[robg]

sometimes swirling the lead into the mold helps the fill out.

[Wooserco]

Bases are better, mainly because I don't have the mold open so long trying to pop the cast out of them now. I still keep more of the GC boolits than the PB, due to the bases. The rest of the boolit can be perfect, but if there is any place that isn't fully filled out it will be a base every so many pours. I believe you are correct, the mold will line out with continued use.

Don't forget to squint just so when pouring.

[243winxb]

3 new Lee molds this year. What works for me- https://www.thehighroad.org/index.php?media/casting-with-lee-molds.4127/full