mould release relief

[sagamore-one]

I came into a H & G 4 banger with a build up of black nasty stuff in the cavities. I suspect it to be mould rerlease.
Question is.... is there any easy way to remove 30 years of built up, baked on mould release from the cavities ???

[billyb]

I have good luck with brake parts cleaner. Acetone or any solvent to brake the bond. Bll

[mooman76]

Sounds like it could be spray moly lube. Some people use that for a mould release. I did for awhile but as you said it builds up plus it flakes off which means respraying it makes it uneven so you have to clean it off or have it uneven. It also changes the size of the bullet a hair if biult up. You could try lappng the mould to clean it off.

[HeavyMetal]

Brake parts cleaner would be my first go to solution!

If that didn't work I go to acetone, which is sold as finger nail polish remover. If that doesn't work you got a problem!

Try these and if it doesn't work let us know and we'll look at other ideas.

[montana_charlie]

For something that thick and old I would use the 'bath-type' carburetor cleaner.
Submerge that mould and let it soak overnight...

CM

[sagamore-one]

Well, so far I've tried; iso alcohol, brake parts cleaner, throttle body cleaner,3 bore cleaners, Kroil oil. Each was vigorously scrubbed with a tooth brush. Starting to come clean on the driving bands , but still looks and casts like krinkle paint in the cavities..
Guss I'll make a run to get some acetone.

[sundog]

Sounds to me like moly loob, too. MEK (my favorite) or carbontet should help. Overnight or more total immersion may help. I also use a bronze toothbrush for tough jobs.

At worst, cast a few boolits and either use the screw in the base or cast through a nut technique, and spin them with a FINE grinding/polishing compound. Go easy on this method.

Final cleanup up may require a magnifier and dental pick.

I've used graphite mould prep with great results for years for some applications and it will not build up to where it will not come off as you described. Judicious use of mould prep can produce very good results (don't spray directly on any surface - best when used with a q-tip).

[codgerville@zianet.com]

I have used 0000 steel wool wrapped around a small wooden dowell. Takes lots of elbow grease, but it works.

[sagamore-one]

Let mould blocks soak for over an hour in Kroil oil, then used previously cast boolits to lap the cavities with J&B bore compound.
Light at the end of the tunnel.............. Molud now displays reason for stubborn cleanup.
At one time the previous owner let blocks form a little surface rust. Not bad , but just enough to hold the mould release compound real GOOOOD.
I just cast 10 lbs of good useable boolits weighing 146 1/2 grains and .360 diameter . I may have gotten lucky.
THANKS to all who responded. I was beginning to question my own sanity.
THANKS again.

[anachronism]

The last mould I bought that had mold release poisoning required me to scrape most of the offending goo out with match sticks & toothpicks, then scrub with acetone & a soft brass brush. It finally came out perfectly, but took a long time to do. Fortunately I bought the mould at 20% of it's true value & when I later sold it, I kept the handles (Saeco). This took a little of the sting out of the project.

[chaos]

I scrub mine out with chore boy copper pads and acetone

[Willbird]

Acetone is not nearly as good a solvent as it seems at first blush. We used it in chem lab to clean lab glass, but I think that was because it leaves no residue. Laquer thinner is a far better solvent than acetone for removing oils and such. Acetone smells like strong stuff but that does mean it works well.

Bill

[Safeshot]

I vote for MEK or Acetone. Slow soak - long time, then use "Chore Boy" brass wool. Good luck