Casting problem with pure linotype

[toolz568]

One of the members asked me to cast some hard boolits from pure linotype. Some look perfect and others look like they were sand blasted. Some actually split when I opened the mold. I started at 850 f and adjusted it to 750 f. I have an idea I need to up the temp to keep everything in solution. Anyone have a band I should be maintaining?

[40Super]

Try setting the pot temp to550 to 600F instead. Your way too hot, even for normal alloys. Lino melts at 450F"ish( I can't remember exactly offhand right now) way lower than pure lead. The bullets are shrinking and splitting. I have casted a couple hundreds of lino 45 bullets(for alloy sweeteners) and they casted rather good, no splitting or cracks.

[btroj]

The mould is way too hot. It isn't that the bullets are shrinking and splitting as much as the fact that a high antimony alloy, which Linotype is, likes to do exactly what he mentions.
Slow down the pace of your casting. I have moulds where I hold the filled mould in front of a small fan for 5 seconds to keep in the right temp zone.
Bet you were casting large bullets too. they transfer more heat to the mould and drive up mould temp faster.
My rule of thumb is the smaller the bullet the cater I cast, big ones need to have you slow it down.

For pure Linotype you could put the pot in the 600 degree range. This will help but you had a MOULD temp issue, not a POT temp issue. The ppt temp does influence the mould temp but the mould temp is controlled by you and your casting tempo.

[cbrick]

It is a pot temp issue and of course mold temp. Lino is eutectic and it is solid at 464 degrees and liquid at 465 degrees. A good casting temp is 100 degrees over melt temp, round that off to 575 degrees and your melt at 850 is 275 degrees TOO HOT. Tin cannot do what it is in the melt to do and that is reduce the surface tension of the alloy going into the mold after 750 degrees and you are 100 degrees over that.

Use a pot temp no more than 600 degrees with straight lino and you'll see a huge difference in your boolits and increase your casting rate because you won't need to wait for the alloy in the mold to cool from 850 to 450 to be solid. That's 400 degrees you need to wait on.

Nothing is "out of solution" as you say, the components cannot possibly separate out of solution BUT at the temps your running your pot the alloy will oxidize quite rapidly.

Rick

[Defcon-One]

They are all right. WAY TOO HOT for pure Linotype which melts at a much lower temp. than Pure Lead!

[toolz568]

Thanks everyone for the help, I am ready to start over and this time I will use a fan. These are .452 and I am casting two at a time.

[MT Chambers]

Use a fan or use 2 or 3 molds at once, alternating them and allowing them to cool a bit.