Strange MP mold problem

[oldhenry]

First of all: the problem is not caused by the design, material or manufacture of the mold. The mold is absolutely perfect as received & I'm so happy that I woke up & realized it was available in a group buy. The mold in question is the 8 cavity 9mm 359-130. It is a mirror image of the Speer Gold Dot 124 gr. that is my carry round which makes me feel good about practicing with something similar.

Trial of the new mold was delayed by yard work & cleanup from "Michael". That cleanup is not finished, but I had to take a break & try that mold.

Break-in took longer than expected.....It took me a while to get accustomed to the holes in the sprue plate being close together & I had some spillovers into the next hole. But after a while it began dropping beautiful boolits (over 800).

I cast on the tail gate of my truck & when finished I was waiting for everything to cool down when a light rain came up. Everything got slightly wet before I could pull the truck fully into the garage. I carried the boolits into the house in a towel that got wet & left them there overnight. The next day when I got ready to size/lube them I noticed a white deposit on all boolits that looked alkaline. I rinsed them in water & the deposit persisted. I then rinsed them in a mixture: 2 qts. water & 1 cup of white vinegar & this removed the deposit.

I have a habit that I carry over from steel mold use where I store molds with boolits/sprues in the mold. I know this does not apply to aluminum molds, but it's a habit.

Today when I was preparing to cast with that same mold, I 1st. found some boolits in the mold discolored & then found 4 of the 8 cavities discolored and possibly etched. I 1st. used brake cleaner which produced minor improvement. I then used liquid detergent with a vegetable brush that produced marginal improvement. I then prepared a 20% white vinegar solution in water applied with a large Q-tip (I figure if it'd help with the boolits it might help with the mold) & it did little to help. Finally I applied Evaporust with the same type large Q-tip with no results. To be fair Evaporust is intended to be used with a 12 hr. soak, but I was reluctant to risk damaging my mold even though Evaporust is PH neutral.

To be fair I used the mold after all of these attempts & when I cast them "hot" (as in frosty) they look pretty good. As a practical matter they should shoot better that I.

I have a scrap aluminum piece 3"X1.5"X11/32" that I'll experiment with in a 12 hr. Evaporust soak.

Has anyone ever done an aluminum mold soak with Evaporust?

Has anyone experienced a similar deposit on boolits or mold?

Does anyone have any suggestions as to remedy or cause?

Since it's from rain water I figure it must be acid rain, but what do I know.

Images:
#1 discolored boolit
#2 overall view of cavities
#3 close-up view of contaminated cavities
#4 close-up of vent lines (that seem to function OK)

[hermans]

I have the same mold, and just to say that it is the best 9mm boolit for me, does not sit too deep in the brass, and feeds perfectly in my 1911 and CZ Shadow, very accurate too!
About your problem, did you clean the mold properly before the first attempt? All I did with mine was to first scrub it with dish washing soap and hot water, then again with a clean toothbrush and denatured alcohol, and then it produced perfect lightly frosted boolits in a short while.

[oldhenry]

Herman,
Thanks for your response. My prep work was similar to yours. I 1st. removed the sprue plate & sprayed each 1/2 of the molds with brake parts cleaner. I then scrubbed each 1/2 with hot water & liquid dish washing detergent with the aid of a vegetable brush (2 times). I dried each 1/2 with a paper towel. I reassembled lubing with the MP lube (no lube in cavities or anywhere near cavities).

My delay in getting good boolits was my fault: 1. temp. not hot enough 2. getting accustomed to the sprue holes. After the correct temp was attained & I got my act together in pouring to the close sprue holes, good boolits began to happen.

One factor that I forgot to mention in my original post: the boolits were water quenched.

My water supply is from our well. Our entire county has a limestone layer about 20' under the top soil. When I use well water I sometimes get small black spots on the boolits. To prevent this I've been using water from our dehumidifier which I thought would be equal to distilled water. The boolits in the wet towel..........the towel was wet from rain water + the water from the wet boolits. When I discovered the white discoloration on the boolits I thought it might be due to the quench water.

In subsequent casting I've abandoned the water quench...........air cooled from now on.

Once again: thanks for your response (the only one so far).

Henry
.................................................. .................................................. ....................
A real sport involves either gasoline or gun powder.......all others are just games

[Hossfly]

Looks like something happened when the rain hit, the condensate from the de humidifier should be good. Your pre pour method with the cleaning of new mold sounds right. You didn’t say what alloy your using, that along with the less than neutral ph rain water could be a factor. We collect rain water off barn to use on Orchid plants and it is on the acid side.

[Grmps]

Maybe the manufacturer has an answer.
I've never had any of the chemicals or lead I use damage an aluminum mold.

You could send a boolit to BNE to XRF and he could tell you if there is something strange in the lead which might give you a start.

[sukivel]

Not sure about the mold but the bullet looks great.


Sent from my iPhone using Tapatalk

[oldhenry]

Hossfly, Grumps & Sukivel,
Thanks for your responses.

Hossfly, the information about your experience with rain water helps (I was beginning to think I was in the "Twilight Zone").

Grumps, I've used this same batch/mix on prior casting sessions without any problem. It's commonly called "range scrap", but my son (now 47....then age 8) named it ABS for already been shot. Keep in mind that it came from our backstop (I have my own range) & 99% of the boolits deposited in that backstop were COWW. I also added some Sn to the mix. I think the problem lies elsewhere.

Sukivel, thanks for the comment. The one showing was from the early batch (before complete break-in) & the base isn't filled in completely. The latter ones look even better. This is my second MP mold & like Hermans states, it's a great mold. So good, in fact, that I have a 300+ batch from a popular brand/model 9mm mold that I'll melt down & re-cast with this fantastic MP mold. This is the only 9mm mold I'll use from now on.

[oldhenry]

Here's my 2 pronged attack:
1. I have that piece of aluminum soaking in Evaporust to see what effect (if any) it has on aluminum.
2. The 2 mold halves are in a plastic container (cavities up) with cavities full of kroil & entire cavity side covered in kroil. The container has a top sealing it against evaporation.

I hope the Kroil experiment works.

Henry

[FLYCUTTER]

It sure looks like the start of aluminum oxidation most likely caused by moisture. Hot bullets left in a mold and stored in a cold garage will do it. I screwed up a pigeon grade shotgun by shooting trap in the winter then bringing it in the house and left it in the case and cleaned it in a week only to find the chamber rusty. The barrel was ok but I had to hone the chamber to clean it up. In your case I would try a pencil eraser and rub it on the cavities. I believe that would clean it up or use a fine grit lapping compound on the eraser.

[oldhenry]

FLYCUTTER,
Good suggestion. I'll give it a try tomorrow with Autosol plus an eraser.

This is why I like this forum........sensible solutions.

Henry

[rintinglen]

This is not what you want to hear but I fear that your mold is permanently etched. If you try abrasive or chemical removal, you will enlarge the cavities as well as rounding off the nice, sharp edges. Not what you want to do. That's the bad news.
The good news is, other than pride of ownership, it doesn't matter. The "disfigured" boolits will shoot just as well as the nice ones. There will be no difference in the groups fired, once you size and lube them.
I have a 311-419 that is heavily etched and pitted from rust, yet the boolits still shoot well. Good luck, but don't despair.

[LongRangeAir]

If the mold is now not dropping easily, use a medical type cotton bue, Q Tip type, shorten the shaft to 2 12" and coat with Flitz petal polish. In a dremel, with mold closed, lightly polish the interior of the cavities.

The finished cavities will look better than new, and release with ease.

Flitz being a chemical reaction rather than abrasive is a big + Here! ;<)

Knife

[oldhenry]

Rintinglen & LongRangAir, thanks for your response.

My present diagnosis has changed somewhat after a 20 hr. soak with kroil. The pencil eracer suggestion by FLYCUTTER (without any abrasive) produced some results (not "like new" results, but an improvement) & this makes me think the mystery material is a deposit. After a brief session with the eraser, I added Autosol & it sped up the cleanup. Autosol's consistence is similar to tooth past....as in not aggressive.

Recognizing the wisdom of Rintinglen's response, I cleaned both 1/2s with dish detergent & hot water, dried & recoated with Kroil. I plan a 48 hr. soak. Kroil will get beneath any deposit if left alone. I'll then do a brief session with a new eraser & cast a few boolits with whatever the results.

I'll let the forum know the results with photos. All I'm after is shootable boolits.

Henry

[oldhenry]

After the 48 hr. Kroil soak, I took the tip from LongRangeAir with Q-tip type cotton swabs in my Dremel, except I mixed LongRangAir's tip with the caution from Rintinglen and used Kroil on the swab (rather than Flitz) and got some pretty good results.....not perfect, but good enough to produce good boolits.

1st. photo shows the mold after the above.

2nd. photo shows the boolits produced this afternoon. When I did my part correctly the boolits from the damaged cavities look every bit as good as the ones from the undamaged cavities.

I'm happy.

Thanks to all who contributed to the solution.

Henry

[BNE]

Good Read, thanks guys!