wrinkle

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  • Last Post 06 July 2012
RUSSELL BURCHSTED posted this 05 July 2012

Trying out a mould. I cleaned the mould with acetone an the bullet comes all wrinkle. temp.750 degreese i lower the degreese to 700 and they still come out all wrinkle. I used this mould before and it came out all nice and clear.

Russ

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CB posted this 05 July 2012

Russ, you must have contamination somewhere else, either in a Q-tip, rag or paper towel. Silicone is the worst nightmare to booger a mold.

I use spray brake cleaner with fair success. Ed's Red gives the least problems when used to oil mold between casting sessions.

If you keep casting 'hot', the mold should eventually clean up and cast good CBA...........Dan

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onondaga posted this 06 July 2012

Acetone is harmless to a mold. It has no petroleum. It is possible you  only thinned the oil that was in the mold with acetone and when the acetone evaporated there was still oil left in the mold that wandered into the cavity from heat.

Another acetone cleaning would not hurt, but I prefer hottest tap water and comet with a tooth brush, then hottest rinse and dry.

Any lube can easily be overdone. I avoid any petroleum products in bullet molds. They flow and gas out when heated and cause bullet defects. Some have success with 100% synthetic 2 stroke oil. I use silicone dielectric grease from an auto parts store, but only the tiniest bit applied to the hinge pins, screws,  guiding surfaces, mold top and sprue plate bottom. I only apply enough that can be rubbed to a shine with a cotton swab. More is NOT better. Just enough to slightly shine--that is all.

Spray  silicone, nearly all brands, contain petroleum distillates. They are trouble for bullet molds.

The dielectric grease is pure silicone (poly siloxane) with a fumed silica filler to thicken it and harmless to bullet casting molds when applied very sparingly and rubbed to a shine with a cotton swab. Get none of anything in mold cavities.

Gary

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onondaga posted this 06 July 2012

Russ:

All wrinkles are not the same in castings. You can get wrinkles with a clean mold. It is really not practical to measure mold temperature, but there is an ideal temperature for bullet molds. 100 degrees less than the alloy going in is the ideal. When the alloy is too hot and the mold too cool you will get wrinkles as the alloy recoils from the cooler thermal front. Those wrinkles appear rough and porous under magnification. Smooth wrinkles are typically from petroleum in the mold.

If you are using a 1 or 2 cavity mold 600-650 is too hot for most bullet alloys except pure lead. A 6 cavity and 700-750 is too hot except for pure lead. I cast much cooler in either instance but preheat my molds to operating temperature first and maintain a casting cadence of 3 drops a minute to keep mold temperature relatively stable at operating temperature.

Anytime you allow bullet alloys to get hotter than 800, the tin in the alloy instantly oxidizes on contact with air right during the flow of metal into the mold and destroys the flow enhancement quality of having tin in your alloy for good fill-out.

If you cannot develop a casting cadence fast enough to keep your mold at operating temperature then the use of a thermometer to assure that you do not heat the metal above 800 is very important for bullet quality.

Gary (retired casting analyst)

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TRKakaCatWhisperer posted this 06 July 2012

Wrinkles: several causes I'm aware of:

Alloy too cold.

Mould too cold.

Contamination on mould.

Filling too slowly.

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onondaga posted this 06 July 2012

TRK:

Filling too slowly is a difficult thing to diagnose and even a difficult thing say it is related to wrinkling.

Filling a mold slowly is not a problem if the fluid alloy is 100 degrees hotter than the fluidus point of the alloy being cast and the mold is 100 degrees cooler than the alloy being cast. That actually produces good bullets with a slow flow or a fast flow because the thermodynamics are ideal.  However when the mold is cool combined a slow flow, then wrinkling is significantly increased.

There are many ways to compensate for ideal thermodynamics in casting and get useable bullets. An extreme example I have demonstrated in practical teaching labs is to cast really hot pure lead into a completely cold mold and get a good bullet the first time.  The metal has to be hot enough to “scare” the cold out of the mold instantly before the lead is anywhere cooling toward solidus, and that is HOT!

Gary

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RUSSELL BURCHSTED posted this 06 July 2012

Thank's ,I will try all the info. Hope it works. Russ.

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TRKakaCatWhisperer posted this 06 July 2012

Gary - I bacame aware of RATE of fill issue when I made my first 1” diameter mould. It was painfully obvious from a bottom pour furnace. Once aware of it, the .458 and .410 diameter results were improved by either opening up the adjustment for flow or with a dipper (larger spigot hole).

Too large a flow on a smaller diameter didn't cause wrinkling, but one could tell the pressure was too much and I got flashing.

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pat i posted this 06 July 2012

Russ try sticking the front edge of the mould into the melt for about a 25 count and see if it helps. If you have some contamination in the mold it'll usually burn it out.

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TRKakaCatWhisperer posted this 06 July 2012

pat i. wrote: Russ try sticking the front edge of the mould into the melt for about a 25 count and see if it helps. If you have some contamination in the mold it'll usually burn it out.

YUP. It also pre-heats the mould. Hit two causes of wrinkles at the same time.

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onondaga posted this 06 July 2012

http://www.castbulletassoc.org/view_user.php?id=97>TRK:

I cast 12 Ga slugs that weigh 1 oz. They will cast with a slow flow if the mold is hot enough.  Sure they will wrinkle terribly with a cool mold. Without an accurate way to measure mold temperature, a lot of casters are left to their own conjecture and interpret the wrong degree of temperature when trying to reach operating temperature needed for good casting.

The casters that are very good at estimating working temperatures are the ones that are very good at instantly diagnosing correctly the surface of castings and have the understanding to correct the flaws with casting cadence instead of turning  the pot up when the metal is already liquid. If the metal flows out of the spout or ladle it is liquid, the correct mold temperature will keep the metal liquid till the mold fills.

The mold temp differences wandering away from ideal have a variety of results that are predictable . Some casters push the edge of the envelope of success every time they cast but manage to get good castings because they are intuitive. The cause end effect of getting good castings is scientific but with good intuition and a feel for things going on while casting, anybody can fumble into success if they try long enough and pay attention to what they are doing that works well.

What is next guys---zone porosity? cold shorts? flow turbulence? swirl casting? venting theory?

Gary

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TRKakaCatWhisperer posted this 06 July 2012

Yup. Been using 12 and 20ga Lyman moulds for at least 30 years. Kept a propane tourch going to keep the hollow-base plug hot too.

I'll stick to the four factors I've listed - only because I've seen how I can adjust each and get predictable results. Rate of flow is readily detectable by variations in weight - I ASSUME from not filling or fully filling. Didn't recognize it until trying to get 200-300-400gr bullets to within +/- 0.1grain.

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