HP modification is awesome, but fill-out still a problem..need advice

[Bluerock2000]

Received my mold back from Erik today and gave it a go tonight. Very satisfied with the HP cavity dimensions and mildly satisfied with boolit turn out. I've still got an issue with fill out and think I found my problem. See pics of mold. It's the same issue I was having before I had it HP'd. Hopefully you can see in the pics the filmy looking stuff on the mold between the cavities and in front of the front cavity. I scrubbed the mold with a toothbrush in a can of acetone and then sprayed with brake cleaner before casting, but apparently still have something on it. My suspicion is that there was something on the mold when I received it and I baked it on but not sure. Anyway, I think this boolit is going to severely outperform the jacketed bullets I tried out of my subsonic single shot and will post results when I have a chance to try it out in my playdoh setup. Any advice on removing the film is appreciated.

Brady

[Bluerock2000]

[Bluerock2000]

[sigep1764]

Looks like lube from the pins or the sprue plate has migrated into the vent lines to me. What happens to the film when you scrub it with dawn or brake cleaner with a tooth brush?

[Bluerock2000]

It's almost impossible to see unless the mold is hot, so I'm not sure. Almost like working blind when cleaning it. Here's a better pic of the issue. The front cavity boolits are much worse than the rear. These are both from the front cavity. But the rear boolits have the same issue to a lesser extent. I think that a more aggressive approach will work but don't want to mess up the mold.

[evoevil]

sandblast with a very fine powder?

[sigep1764]

Well, you could cast fast and burn it off. Or at least get it hot enough that you could wipe some of it off. Those boolits look like they are starting to frost on the sides from the heat of the mold and the melt. I can only see wrinkles on the tops of the boolits. Where on the mold are you lubing?

[jcren]

Have you tried scrubbing the HOT mold with denim or burlap?

[Bluerock2000]

Well, you could cast fast and burn it off. Or at least get it hot enough that you could wipe some of it off. Those boolits look like they are starting to frost on the sides from the heat of the mold and the melt. I can only see wrinkles on the tops of the boolits. Where on the mold are you lubing?

I'll try wiping it off with denim when it's hot like you and jcren suggested. I haven't lubed the mold yet as it's new and wanted to make sure that wasn't the problem so i just cleaned it and started casting. some of the boolits are frosted on one side because I was casting as fast as I could and trying to burn the film off. Thanks for the responses.

[bosterr]

Who made your mold?

[Bluerock2000]

Who made your mold?

Accurate. It's the 43-350R sized to .432 with the gas check and lube grooves removed.

[Bluerock2000]

My initial post was inaccurate. I used carb cleaner, not brake cleaner. I read a post in the archives that some carb cleaners have protective chemicals in them that can varnish when heated in the mold. Is anyone familiar with this?

[HATCH]

carb cleaners have a lube in them.
Brake cleaner doesn't

[Bluerock2000]

Lol. Well, that explains why I couldn’t clean the problem away using carb cleaner. It was the problem. Thanks Hatch.

[Minerat]

Have you you tried scrubbing the discolored area with piece of lead or alloy. I have use that method to clean up some nasty stuff on moulds.

[gwpercle]

Acetone and a tooth brush will not leave any residue , scrub and soak the blocks, that usually gets them clean.

[Walter Laich]

while the type of cleaner use used is most likely the problem I find that new molds can require 4-5 'heating to temp' and cooling periods before everything is burnt off. All depends on brand of mold (Lee usually require this)

[Wasalmonslayer]

Just a tip I have cleaned up many aluminum molds that have had bees wax and many other items baked on with a mild solution of wire wheel cleaning acid.
Mix it very mild and spray on with a spray bottle let it foam slightly, rinse, repeat till the mold is bare. It will be a white haze and very very clean.
Reseason with a dusting of smoke and it will cast like a million bucks!!

You get wire wheel acid cleaner at auto parts houses.

It’s kinda like brill cream a dab will do ya.
Please proceed with caution it is acid!!

[Bluerock2000]

Thanks to all for the replies. I still have not been able to completely remove the film but have not tried all the suggestions yet. After further inspection and researching through the archives I don't think this is my problem. It's not in the cavities and the vent lines are clean. I'm fairly certain it's SBS, due the large double cavities in this steel mold. I'll continue to play with mold temp, cadence, and pouring technique. It is definitely frustrating having one side of the boolit looking good and the other like the surface of the moon.

thanks again.

Brady

[Bluerock2000]

I'm getting closer. Lowered alloy temp, opened pot valve all the way, and tilted the mold forward when filling the front cavity and toward me when filling the rear cavity. Kept stream half on sprue plate to swirl into cavity. This results in the frosting and pitting on the side of each cavity that the mold is tilted toward, concentrated around the parting line. But it's definitely better. I'll try pressure casting next time and I've also got a Lyman ladle arriving tomorrow and will try that to see if it helps. But I managed to get a few that are shoot-able and PC'd them yesterday. As always thanks for the help.