Troubleshooting Casting Defects

[Conditor22]

"I did the 350F warm-cool cycle three times and then deposited carbon inside the cavities with a Bic lighter, following instructions that came with the mold."

Heat cycling helps build a patina which improves castability.

I don't see where/when you cleaned the mold and how you cleaned it.

IF you heat cycled the mold before you cleaned it I would suggest cleaning the mold with either acetone, carb cleaner, brake cleaner scrubbing the cavities well with a toothbrush (any nylon bristle brush, [I use a denture cleaning brush from the dollertree])

Warming a mold on a hotplate set to 400° helps the mold cast well from the start

"Alloy is 92-6-2 Pb-Sb-Sn from Missouri Bullet Company" this is a good, easy to cast with alloy, though a little hard for most applications

In my shame, I melted my mistakes. Too bad I can’t do that in real life == we've all had poor results when we started casting (and often with a new mold) this is part of the learning curve.

Next time I’ll use the thermometer, and see if I can get smoother parts at some temperature around 350F. ==this doesn't make any sense to me

FWIW - the roughness was like pitting, not like frosting. I don’t see colors in the pitting to indicate debris inclusions, but they could be really small. == pictures are worth 1,000 words and make it much easier for us to help, many people don't describe things the same way and pictures don't lie

Diagnosis:
clean the cavities well (don't smoke the cavities at this point)
preheat the mold on a hotplate set at 400° (I turn my hot plate on at the same time as the casting pot)
Set/heat the casting pot up to 720°
Cast a few mold fulls with a quarter-sized puddle on the sprue plate, (wait for the sprue to frost over before cutting)
Now IF you're not getting smooth boolits lightly smoke the cavities.

One way to test the cavities to see if it's a heat problem is to pressure pour -- hold the mold up to the spout and fill the cavity stopping the flow of lead after you lower the mold and get a puddle on the sprue plate.

this is the important part---- post pictures of your results

[justindad]

Seems the first issue to address is the temperature. There seems to be a bit of confusion. Does the OP know what temperature he was casting at? A simple way if you don’t have a thermometer or you aren’t sure if it is correct, is to keep heating the alloy until the boolits begin to have a frosty look and then turn down the heat some. Frosted boolits are fine to shoot too.

I heated my molds to 350F in a toaster oven, and then went to casting. I’m pretty sure Inwas moving slowly enough that the mold cooled off.

When the top of the molten lead was perfectly clean, my IR thermometer gave me somewhere around 650F, but that method was found to be wildly inaccurate. After deciding the IR data was junk, I adjusted the heat knob up and down looking to see a change, but then my mold cooled down.

I’ll see how high I need to set the pot to get frosted bullets, and keep the mold in the oven when not pouring. Then I’ll cool the pot until frosting disappears.

[justindad]

Way to low temp, even 350 C is only 650 F and barely liquid. That alloy needs to be 730 F or so. Something big wrong with temp measurement?

350F is what I used to prewarm the mold. My measurement of molten lead turned out to be garbage.

[Stewbaby]

Get a PID from Hatch so you don’t have to keep fighting those temp issues

[justindad]

Pitting without residue, still giving off oil vapor and not enough heat/time in the break in cycles.

When you can provide photos, please show the nose, sides and bases so we can get an overall view of the problems you have encountered.

That’s the main issue. Perhaps I need to clean the new molds better, and repeat the warm-up & cool-down break in process, leaving the mold at 350F [or higher] longer than the first time.

I’ll save a few of my next failures for pictures

[white eagle]

Is there a thread with examples of different casting defects, and how to resolve them? Maybe some guidance on what imperfections are acceptable for plinking?

My first session today gave me 95% reject rate due to rough surfaces, with a few wrinkles too. I might be too picky on the rough surfaces.

your problems will cease the longer you cast
if you are fresh on the mold it may be the mold will get better as the casting sessions get more and more
seasoning it as you go along
wrinkles are a sign something is not up to temp either the alloy or the mold or both
hang in there

[justindad]

Thanks for all your help! Not only am I fresh on this mold, but molds are fresh on me!

[JonB_in_Glencoe]

Is there a thread with examples of different casting defects, and how to resolve them? Maybe some guidance on what imperfections are acceptable for plinking?

My first session today gave me 95% reject rate due to rough surfaces, with a few wrinkles too. I might be too picky on the rough surfaces.

justindad,
Welcome to the forum.

A casting defects thread is a great idea. I don't think there is one, at least not one with numerous photos and solutions.

You've received some good info so far.

Let me address one thing, that I don't think anyone else has covered. Wrinkles...
When I first started started casting, the first time I cast 22 cal boolits (NOE 225-55-FN), I got wrinkles. It's difficult to keep a mold with small (22 cal) cavities, hot enough...Heat is the secret to eliminate wrinkles. I finally figured out (with a suggestion by someone here), to use a Hot plate to preheat the mold, and when necessary, to re-heat the mold, if I am not able to cast fast enough for it to remain hot enough.

ANYWAY, the point I am trying to get to is, I did a test, a shooting test. I loaded a bunch of these wrinkly 22 boolits in 222 rem (let me mention, that I did inspect these for other flaws, and also, I did cull some that had real bad wrinkles). I also loaded a bunch of the same boolits that didn't have wrinkles, they looked perfect. I made sure to use the same alloy, same sizing, same lube, same loading tooling and procedures, into the same headstamped cases, and then went to the range and shot them. I was shooting off a bench at 100 yd targets, with a scoped Savage 340. Now, I'm not sure of it was the day? or what? but the wrinkly boolits shot better groups than the perfect boolits ...and those groups were the best that I've shot with that rifle


Do you suppose those wrinkles have a similar effect as the dimples on a golf ball

[GregLaROCHE]

I heated my molds to 350F in a toaster oven, and then went to casting. I’m pretty sure Inwas moving slowly enough that the mold cooled off.

When the top of the molten lead was perfectly clean, my IR thermometer gave me somewhere around 650F, but that method was found to be wildly inaccurate. After deciding the IR data was junk, I adjusted the heat knob up and down looking to see a change, but then my mold cooled down.

I’ll see how high I need to set the pot to get frosted bullets, and keep the mold in the oven when not pouring. Then I’ll cool the pot until frosting disappears.

IR thermometers don’t work well for casting boolits. You need a good thermometer that goes into the lead or a PID. Otherwise, do as I said before. Heat the alloy until the boolits begin to frost and then turn down the heat. This may sound like a crude approach, but it works. You can fine tune temperatures later.

[WRideout]

After a quick review of the NOE web site, it looks like your mold is probably aluminum. IME (using Lee aluminum molds) they like to run HOT. With my Lee dipper pot, I use an alloy of range scrap and tin, and turn the heat control on the pot to 3/4 of scale. Any more I preheat the mold by balancing it on the edge of the pot, or if I'm in a hurry, dip a corner of the mold into the lead. I usually get one or two pours that are rejects, but soon begin getting good, sharp boolits. I cast until they start getting frosted, then turn the heat down a little. I have never measured the temperature of my pot. If in doubt, turn the heat up until the results tell you it's right.

Wayne

[justindad]

I think so need to back up about a month here... I bought ~65 lb of lead, and it came in 8 lb sections. At the same time, I bought a Lee 10 lb bottom pour pot (only one available). The pot was barely able to hold the 8 lb segments, but it did and I melted it all down into 1 lb manageable ingots... except I left the pot full for when my molds arrived, hoping that would be a reasonable rust preventative (probably a very bad idea).

So last night I fluxed with some saw dust and stearic acid flakes. Not much dross came up, which seemed reasonable given it was purchased lead. Tonight I started the pot at 80% power, and noticed the lead at the bottom of the pot melted sooner than the lead exposed to air - perhaps the heat did not evenly distribute due to the higher setting and shorter time. Now the bottom 4 lb leaked into my ingot mold, while the solid top portion held the valve open. I figured it’d be good to see if any dirt was in there, so I did not refill it. I fluxed with stearic acid only, and nothing new happened.

Then I started casting with my mold at 350F, and saw sharper corners with the same pitting (very few bullets showed any foreign bodies in the pitting). Then I turned the mold temperature up to 400F (actually measuring the mold with a thermometer from NOE today), and the only change is all corners are crisp. Then I fluxed with saw dust and stearic acid. Fluxing now between each casting. Still no changes, so I turned the pot up to 90% power, and saw the molten lead turn red with no other changes (no frosting).

While leaving the mold in the toaster oven, I inspected the bullets. Having fluxed & cleaned before inspecting my work, I was surprised to find A LOT of dross had risen to the top before my mold got to 400F. This happened two or theee times, getting worse each time. Then the pour valve started getting sticky. So I figured the pot was dirty and emptied it into the ingot molds. The last full ingot cracked into two pieces when I knocked it out of the mold, and it has a burn mark in the middle. So I laughed at my glaring ignorance, and stopped until I can clean the large chunks of dirt out of the pot.

Dirt the last ingot crack because it is loaded with antimony, from the stream of 65 lb? Did it crack from dirt? Or both?

The pitting I have been seeing is in the pictures here. I may need to get my Fuji out and get real pictures tomorrow, since my phone isn’t doing a great job - just let me know.

I imagine I need to buy a hardness tester and sort my ingots... if I can find one.

[bruce381]

mold to cold try 450 on you oven.

[Land Owner]

Pre-heat. Pre-heat. And pre-heat some more. After pre-heating the mold, "float" the mold on top of, and in the melt. Leave it there a while...+/- 2 minutes! ymmv. Turn the mold over and "float" the spruce plate in the melt for +/- 2 minutes too. Do both sides a couple of times. You can tell when the melt no longer sticks to the mold that the mold is ready.

Take the mold from the pot, tap off any melt sticking there, and pour a few dozen. Set the mold so it "floats" on the melt (or now smoldering saw dust). Inspect boolit(s). Wrinkle and frost free should follow at about 725F.

Use saw dust and a small amount of candle wax as flux. Cover the top of the pot liberally with saw dust and a flake or two of wax. Acid is expensive, imo. Even "floating" the mold on top of the smoldering sawdust will allow it to absorb heat.

My last session with a 2-cav., 22 Bator mold heated this way (not HP), produced 1183 keepers and 17 rejects. I was ecstatic! The planets aligned. HP molds need heat, especially on the internal hp pins. The way I give them heat is dipping the mold.

Rejects are a part of the learning curve. What works for you...not all defects are "bad". Plinkers are fun (they add expense as you "throw away" expendable components - though not for nothing) but nice boolit are confidence builders. This hobby gets better with time. Heat is your friend with molds.

[justindad]

Take the mold from the pot, tap off any melt sticking there, and pour a few dozen. Set the mold so it "floats" on the melt (or now smoldering saw dust).

Do you leave the ashes from sawdust on top of your pot while casting?

[justindad]

The 450F pre-warm temperature for the mold really helps. I got some frosty bullets, and I still have some surface roughness. I’m thinking that the surface roughness will improve as the mold ages. If it causes any problems, I’ll compensate with a polymer coat until My casting skills improve.
I cleaned the pot today, but I do not believe that was the main issue. I think my cracked ingot was caused by excessive heat in the pot. I’m going to anneal my frosty bullets at 375F.
Here’s a pic of samples from today.

[gwpercle]

Don't smoke your moulds ... the smoke causes the roughness on cast boolits and just mucks up the blocks .
If you must use some kind of mould release then use a spray on dry lubricant that contains Micro Teflon particles (PTFE) in it . The Teflon film doesn't contaminate and being teflon ... nothing sticks !
The first time I tried this the boolits jumped out of a sticky Lee mould .
Once a good mould is broken in you wont have to use anything ... it's just getting that new mould all broken in that tricky ... Keep Casting with it and soon it will be doing right .
Also make sure you're holding your mouth right when casting
Gary

[justindad]

If you must use some kind of mould release then use a spray on dry lubricant that contains Micro Teflon particles (PTFE) in it . The Teflon film doesn't contaminate and being teflon ... nothing sticks !

I am getting some sticking in the molds. Does it matter what sort of liquid is carrying the Teflon?

I found this: https://www.modeltrainstuff.com/Labe...All%20Products

[Land Owner]

Do you leave the ashes from sawdust on top of your pot while casting?

You bet I do. Leaving it there to smolder increases the flux (stirring without stirring) of tin and alloy constituents to help them remain distributed rather than some (like tin) disassociating by cooling at the surface of the pot where the temperature is lower. The sawdust smolders, and if I have included any from resin soaked pine, it smells nice. Crayons used as flux smell nice too. Pick those up from ANY restaurant that serves kids. They toss them but they're great for flux.

[Burnt Fingers]

Teflon decays into a toxic fume at around 450°. Personally I would avoid Teflon on my molds.

I've smoked numerous molds and never had a problem.

[popper]

stearic acid flakes for fluxing - why? Cheap SS isn't acid resistant. The pot will turn brown and 'rust' - which you scrape off - no - not rust but oxide alloy. Just use bees wax or candle wax. I tried the sawdust thing, got lots in the bullets I cast - ugg. Get the wax to melt only, stir a lot. Then turn up the heat and get it to burn. Basically floating the junk to the top where the wax captures it. Burning then 'reduces' any good part of the alloy into the melt and burns off 'consumable' stuff. Left over gets skimmed. Get your alloy to 720F, mould to 400F and start casting. Sprue plate (alum. mould) is hardest to get hot but will cool slowest. Sprue will go through 2 color changes, first is dull, second is whitish. Cut on 2nd. Invert the mould and tap the handle bolt with something hard to knock bullets free. Close the plate when mould is inverted, flip upright and pour again. Repeat. Lube plate pin and handle bolt (+ mould attach bolts on the handle) with 2 stroke oil, you get a feel for it after a while. Just some (not dripping) oil on q-tip, dabbed on TOP of the bolt. I use a pencil, scribble heavy on the plate bottom and mould top at the pin for plate lube. Do NOT use AC eco oil - it hardens and you never get it off.