What the heck is this in my mould?

[Mark85304]

I got a new Ranch Dog TLC-460-350-RF six cavity mould. I cleaned it with soap and water and a soft toothbrush, then mineral spirits. I made sure it was clean and dry before using it. Last night I cast around a hundred boolits with good success and then I noticed the boolits appeared pitted. I set the mould aside and picked up another mould and began casting with that one. I cast several hundred Ranch Dog TLC379-235-RF boolits from that six cavity mould with no problems.

Today I inspected the 460 mould and noticed there is stuff stuck on the surface in the cavities. It looks like boolit alloy. It does not come out with my finger nail or a tooth brush. Here is a picture.

http://i1194.photobucket.com/albums/aa373/tangochaser/DirtyMould.jpg

Any ideas what caused this and how I can remove it?

[tomme boy]

I had a couple of Accurate molds do the same thing. After a few casting sessions it went away. I tried to clean them a few times an it would not come off. I would like to know as well.

[Mark85304]

After reading Tomme Boy's reply that his went away after a few casting sessions, I went back out and cast some more. This time I turned down the temp to just over the point where the alloy went liquid. Kept the mould hot and rotated between the 460-350 and another large caliber six cavity Lee mould. I get about 5 cycles before signs of frosting and then I switch moulds. I am leaving the mould open to cool. That seems like a good pace for two six cavity moulds with lower heat.

My Lee 4-20 pot temp control is now at 5.5 rather than 7 like I had it. I am getting much better boolits all around. Incidentally, the "junk" in the mould is gone now.

[jblee10]

I'd be more concerned about that big glob of lead between the mould faces, than something making my boolits look a little funny. That stuff between the mould face makes me think you are opening too early.

[geargnasher]

If you heat cycle the mould in an oven three or four times before casting with it, it builds a patina in the cavities that resists sticking. Sounds like you could benefit from a lead thermometer, too. Those Lee pots will hold temp all day long as long as the ambient stays the same, there aren't any drafts, and the lead level stays constant in the pot. As the lead goes down, the temp goes up, a LOT. With WW alloy and my particular Lee pot I start at 8 and end up on 3.5 by the beginning of the last 1/4 pot with my 20-lb Lee, all to keep the alloy at 100 over full-liquidus, which is about 675 for that alloy.

Gear

[Mark85304]

Those Lee pots will hold temp all day long as long as the ambient stays the same, there aren't any drafts, and the lead level stays constant in the pot.

Yep a thermometer is in order. I'll get one right away.

BTW it is 10:30 PM. I just finished casting for the night and the outside temp just fell below 100 degrees.

I'm learning a lot here. Thanks.

[geargnasher]

For a minute there I thought you were in Texas! I've been known to nap in the evening and get up for a few hours around 2 a.m. and do my smelting, then hit the rack again for a couple hours before work. I did a marathon smelting/ingoting/alloying session last "winter" so I won't have to go through that again for a while.

Gear

[TomAM]

That often happens with aluminum for the first couple sessions. It's easily wiped off with a Q-tip while the mold is hot. After the mold has been used a couple times, the surface is seasoned enough and the problem stops.

[Mark85304]

I'd be more concerned about that big glob of lead between the mould faces, than something making my boolits look a little funny. That stuff between the mould face makes me think you are opening too early.

Thanks for pointing that blob out to me. I put my finger on it and it lifted off onto my finger. It did not appear attached.

If I'm opening the mould too early, the boolits sure do fall out nicely.