It's got to be barometric pressure, that's all I can figure.

[Trey45]

I sat down yesterday morning behind the lead pot and cast about 20 pounds of the MP 45-270 SAA boolits. It was a nice cool rainy morning outside and felt about perfect for casting in the shop. After the mould heated up it dropped perfect boolits every time. A real joy to cast with.

This morning, same temperature outside, no rain though, and I can't get a decent boolit poured to save my life. The only difference is barometric pressure. Same alloy, same heat, same mould! The cavities are clean and oil free as well.

I've noticed this before that when it's raining outside I get some of the prettiest boolits poured, but never has it been such a polar opposite from one day to the next, it's like a switch was flicked somewhere that turned off the pretty boolit option.

[mdi]

The difference in pressure is actually very small (in psi from a high pressure day to a low pressure day). I would suspect, if there is an atmospheric effect on casting, it would be humidity.

[popper]

Neither. Rain kept the bugs away. More peaceful when it rains. New batch of alloy?

[runfiverun]

it's the humidity.
i have a small swamp cooler in my shop which i use to add humidity to the shop in the summer and boil a pot of water on the wood stove in the winter.
i have noticed that on high humidity day's my boolits weigh more too.
lot's of times even if i have something else planned i will cast when it's raining or snowing,and it's not just because i don't wanna get wet.

[Trey45]

I think there's something to the humidity. I waited for it to start raining again and just cast a bunch of H&G 68 clones out of an MP 45-200.
http://sphotos-a.xx.fbcdn.net/hphotos-snc7/420385_431122560278555_1172246662_n.jpg
That's 30 minutes worth of casting right there, maybe 3 culls in the bunch.
What is it about high humidity that is conducive to superlative casting sessions?

[MikeS]

If it's high humidity that makes good castings, then there shouldn't be a reject boolit in all of south Florida!

Maybe that's why I don't suck at casting boolits!

[felix]

Really, it's the condensing atmosphere that does it. Humidity with downward pressure. The very best time is setting up for casting outside during a high humidity summer day, and then start casting when you feel the dampness fall out of the sky after the sun goes or starts downward taking the air temperature with it. Florida? Maybe, but it might not work as expected because wind usually screws up the moisture patterns on or around the mold. ... felix

[Frozone]

I don't know felix. I did 2 sessions yesterday.

The first one I did a couple hundred, I had about 10% culls. This is normal with this mold the HP pins give me fits keeping them up to temp. refilled the pot and did another couple hundred.
It had started to get dark and a fog was coming up. 50% or better culled.

I went back today with clearing skies, remelted the culls and did about 150.
I only did a quick checked so far as I put em in the drying pan but it looks like I have very few culls - only the ones I know I screwed up.

[williamwaco]

I have found that the number of culls is directly proportional to how much of a hurry I am in.


.

[mdi]

Perhaps it's the change in atmospheric pressure on the brain. Low pressure days and the brain is subject to more blood flow and you feel better. And if you believe that I got some property in So. CA to sell...