Mold deposits----How to deal with?

[smokepole7]

I am not new to boolit casting, having been involved in it for about 50 years. However, over the last two I have experienced deposits of some sort which have incapacitated several expensive custom molds. Whether it was too hot, wrong alloy or what, I have basically lost the use of two Paul Jones molds and one Pioneer-Leeth. The problem is that the boolits don't fill out around the parting line. I have tried turpentine, boiling, a scribe in the vent lines and even a wire brush in the cavities. Yes, I even lapped the Pioneer mold with rubbing compound! Suggestions?

[Smitty's Retired]

So, what I am reading, you are having a fill out problem??? Pictures of the mold would help. If the mold is clean, ventlines are clean, and mold surfaces have no deposits, it could be the mold is not up to temp, you may need to check what temp your alloy is at, may need to cast a little hotter, or you may need a little tin in your lead, or a combination of all. That has been my experience when I had this issue.

[John Boy]

I have basically lost the use of two Paul Jones molds and one Pioneer-Leeth. The problem is that the boolits don't fill out around the parting line.Smokepole, the caliber - weight - alloy and casting temperature would help further the posts to determine your issue.
Paul and Fred both make excellent molds. So, I'm leaning towards a casting issue such as casting temperature that allows the sprue puddle to frost too quickly or the handles are not allowing the mold halves to close exactly

BTW, what do these deposits look like? Individual deposits or a line of them?

[SP5315]

As a wise man once said to me, "A picture would help a lot."

[runfiverun]

what is your alloy??

[Bent Ramrod]

I think I had the same problem with a Paul Jones mould. It may have been that I was casting too fast or too hot, but around the parting lines there were tiny lead deposits that didn't come out with use or brush out with a copper brush. They made a pattern of flats and dimples on the boolits along the parting line. Eventually I coated a boolit with 320 Clover compound and lapped the mold for twenty seconds or so. That took the stuff out, and after the cavity was reoxidized the mould cast fine and the parting line deposits have not reappeared.

I also went back to the higher melting, mostly lead alloy I cast with normally. I believe it was a wheelweight/lino mixture, running too hot and cast too fast, that broke at the parting lines as the boolits fell out and caused the trouble.

[TCLouis]

As otthers have said, . . .
New molds,
Have you used them prior to the deposits
Caliber,
Alloy,
How are the molds incapacitated
Deposits,
Build up slowly
Just suddenly there
What do the look like,
how big are they,
hard,
soft,
where are they located?
Sounds like they ate blocking the vent lines, Are they?

Only way to long distance analyze is to have some info to digest/analyze

[smokepole7]

I think Bent ramrod has had an experience close to mine. There are actually no deposits visible to the naked eye but something has to be in there. My alloy is currently 25-1 but I have experimented with antimonial alloys and think that is where the problem started. Maybe from running too hot or too fast. When I experimented with WW added to make an alloy 97-1.5-1.5 is probably where I went wrong. I fire 1600-2000 competitive shots per year in BPCR, burning 15+ lbs of black powder. My PJC molds (one .40-423 gr and one .45-540 gr) have been used to cast many thousands of boolits and they just went bad when I experimented. TCLouis has suggested that I try wood in an effort to clean it up before getting too agressive with abrasives. Any other suggestions?

[RickinTN]

Smokepole,
I know I'm a little late to the party, but I do have a suggestion based on an experience I had recently. I am a new caster, and in my first session I tried 3 different molds, and did learn that they each have a personality. I had one mold that was very stubborn (and still is) that never cast a good bullet. I couldn't see anything in the cavities with the naked eye, but with my 10X power jewelers loupe it was very obvious that I had small alloy deposits in random places in the cavities. Mine were most prevalent around the driving bands and crimp groove areas on the mold, and were very stubborn. I tried a very stiff toothpick to scrape them off and had no luck. I didn't want to get any more agressive with the mold. I decided to coat the cavities in Kroil penetrating oil overnight. The next day with a toothbrush and Dawn dishwashing liquid the deposits brushed out fairly easily. I tried the mold and produced bullets which were well filled out and the alloy "stuck" to the cavity walls did not re-appear. To my thinking the problem was from some of the alloy "soldering" itself to the walls of the cavities. I'm thinking mold temperature played a part.
The Kroil soak worked wonders in helping to clean the cavities.
I noticed as well that we are probably neighbors as I live in Franklin.
Good Luck, and I hope this helps,
Rick

[smokepole7]

I hunted up my loupe and examined the cavity in my .40 cal Paul Jones Creedmoor. I could see some deposits but am not sure they are where the bullets were affected. The blocks are currently soaking in Kroil.

[RCE1]

I've had some luck with JB Bore cleaner and a piece of 0000 steel wool, especially around the sprue plate and block tops if lead is smeared. I've also used it on a plastic bristle brush and an electric screwdriver, spun in the cavity. Thorough cleaning afterward is required, of course.

[tomme boy]

The molds need a very good cleaning. Then they need to be oxidized. Run them through about 10 heat cycles on a hot plate. I have a few aluminum molds that do the same thing until they get at least 10 casting sessions on them.

[smokepole7]

Well, the Kroil and toothbrush did not work. I cast about 30 boolits after the treatment and the same faults showed up. I do think they are not quite as bad as before. With the loupe I can see minute deposits at the parting line. I will try the scribe again before getting to lapping. I have grits from Turtle wax Rubbing Compound to JB to 180--320--500-800-1000. These molds are iron or steel. I do not want to increase the size of the cavities. The .45s are already too large for one of my barrels, requiring sizing from .459 to .457 for the Green Mountain .456 GD. It is .448 across the lands so very tight.

[shotman4]

you didnt clean the oil off the mold first. need to make sure that ALL the oli is off a new mold . THEN use the Kroil. if you cast with a new mold not cleaned you have a BIG problem. it takes a lot of time to clean a used mold . I have had several sent and all the guys like the way it cast when it was sent back
NEVER cast with a new mold, till is cleaned from the cutting oil

[MT Gianni]

Dip the corner of the mold in the melt until it is warm or put it on a hot plate @350 F for 30 minutes. Wipe all the deposits off with a heavy paper towel such as a shop towel. Cycle it for three heat cycles in a 350 oven when it is clean.

[smokepole7]

Success at last! After trying boiling, Kroil, stylus, I finally lapped the Paul Jones Creedmoor mold with 1000 grit silicon carbide. This did not remove the deposits but did produce better looking boolits. In desperation, I lapped it with 500 grit and voila! I coated a boolit with a screw in the back and ran it in the mold very slowly for about 12 seconds, actually until it freed up. This apparently removed them and after boiling the blocks in detergent and water,I cast 100 good-looking 423 gr PJC. As to cause of the deposits to begin with; I feel it was running too hot with some antimony content. I was experimenting with 97-1.5-1.5 alloy and was heating it to the same temp which I used with 25-1 lead/tin. I have two other custom molds screwed up the same way. At least now, I feel OK about dealing with them.