Kroil to treat bullet molds, seems very odd

[Kenk]

Have read a few articles recently regarding Kroil in casting molds. One person in particular would put Kroil in the cavity over night, and then wipe it off with a cue tip. The clams are that it penetrates the mold and help eliminate many of the wrinkle issue?s people experience, as well as being a release agent. I?m under the impression that you don?t want anything oily in or around your molds, and just doesn?t seem right. Kroil is some pretty amazing stuff, but for this application, I just don?t know
Thanks

[The_Shadow]

I store mine with a cast bullet sill inside, place them in plastic bag.  But they are stored in the house with air / heat.

[Kenk]

That?s a really good idea, Thanks!

[RDub01]

Are we talking aluminum molds or cast iron? I would say absolutely not for a cast iron mold. Aluminum is a different metal with its own properties. You are supposed to 'smoke' the aluminum mold before casting. I've not heard of this, but there might be something to it...

[Kenk]

Pretty sure they were referring to aluminum molds, just seems odd having anything oily around, and or in your mold cavity

[blaster]

that does seem odd since Lee tells you to clean & degrease the mold before use.

[John A.]

I wouldn't put any kind of liquid lubricant in any of my molds.

I can say it unnecessary, would probably gunk it up eventually, would likely smoke from the heat stinking up the place too.

Seriously, a book of matches will keep the bullets you cast from sticking.   Nothing else is needed.

[sqlbullet]

Wrinkly bullets with an aluminum mold are from the mold being cold or from mold cavities being contaminated with anything that will vaporize when exposed to heat, oil being the most common.  If you get the mold good and hot before the first case, you will get very frosty bullets, and you will have already cooked off about anything that can vaporize.  This is how Kroil works out.  If you examine the MSDS for Kroil or AeroKroil, you will see the product flash point is 132?F.  Your mold should be triple this temp when you start casting, so Kroil is long cooked off by the time you cast.

Richard Lee suggests smoking the mold with a butane lighter (not a candle!).  There is lots of other lore and snake oil out there.

That said, I see no benefit in my years of casting to any of these tricks. 

I apply an extremely thin film of two stroke motor oil to the bottom of the sprue plate, top of the mold on the side the sprue cuts towards.  I do this with a cotton swab.  To give an idea of how little is needed, NOE includes a 2 Dram (1/8 oz) bottle of oil with their mold, and it is intended as a lifetime supply for that mold. (https://noebulletmolds.com/site/shop/bullet-casting-reloading/sprue-plate-lube/sprue-plate-lube-with-wrenches/).  The instructions say use a drop, but I have never used that much.  I take the dropper top off, and swab maybe 1/4 of the threads inside the top where some oil has accumulated.  Also, note, this is done with the mold at temp and with lead in the cavities.  This lubes the sprue plate and it prevents a hot sprue smear from sticking.  It has nothing to do with wrinkly bullets, and it is done with the mold cavities full to help ensure no oil gets into the cavity.

[Kenk]

Thanks, now that I?m using a hot plate and getting my molds up to around 400, everything is looking a lot better. I haven?t experienced any release issues either. It appears this Kroil thing is more internet hogwash

[DDRiller]

I use the sprue lube on my molds, s Sqlbullet says it doesn't take much.  I had one mold out of about 30 that the bullets stuck in and tried many tricks and none of them helped.  I found some Hi-Tek-Lube bonded mold release that bonds to the mold cavities.  It is mixed with alcohol and evaporates.  The bullets just fall out of the mold now.

[sqlbullet]

I will add that time in mold can affect mold release.  The lead and aluminum change dimensions at different rates as they cool, and if I leave them in a bit too long, it takes an extra tap or too on the pivot bolt to get them to drop.  Cadence is everything!

[Kenk]

Thanks sqlbullet, being so new to casting, I have yet to figure out how fast the alloy sets up in my molds. Is there a way to tell when they are hard enough by looking at the sprue puddle, or any other way? Because I only have two molds so far, waiting extra long really cuts into my production time
Thanks again!

[The_Shadow]

Ken, I watch the sprue puddle and as it freezes, I cut it open.  By watching the sprue freeze it helps to maintain mold temps.  Aluminum molds tend to cool a little quicker.
The larger multi cavity molds can retain more heat and might take a little longer to cool and freeze the sprues, that can be seen if sprue puddles tend to slide off.
I drop mine in a shallow box with some old blue jean leg cutoffs and air cool.
When you get into the rhythm things will move along a nice pace.

[Kenk]

Thanks Wade, my concern was trying to remove the newly cast bullets too quickly from the mold, so instead I am likely waiting longer than necessary.

[sqlbullet]

The sprue goes from "shiny" to "hazy" as it freezes.  As soon as it transitions to hazy, I cut.  If I get a smear, I wait an added 2-3 seconds before I cut the next one.  Cadence that maintains mold temp is key.

Also, sprue should cut with minimal effort.  If they get too "cold" they get hard to cut.  Most of my bullets have a bit of sprue tear out on the base, which I prefer to the alternative which is a hard to cut sprue.  Tear out in the middle of the base doesn't matter.  Near the center, it introduces very little variation in bullet concentricity or weight.