long streaked void - RCBS iron mold

[cocowboy]

have been pouring a couple of years with my RCBS 435 gr postell mold.. all of a sudden i find long streaked voids on the nose along sometimes with an odd shaped indentation on the nose... have cleaned mold - checked vents - cleaned vents - cleaned mold again - pouring around 750 degrees... just nuts I say... [smilie=b: ... anyone have any suggestions??? TKS... Deadlast

[TexasGrunt]

Smoke the mold.

[cocowboy]

have used "dropout" graphite in the past, no issues until now.... have used kroil with no issues.... will try to smoke mold and see what happens... i just find it odd that one day all in the world is good... the next it all went to heck.... tks for note...

[country gent]

Have you by chance changed the alloy, temp, or pouring technique? If not look it over good under magnification and make sure theres no corrosion or odd changes in the finish. Also clean it in a solvent ( acetone, alchlol, lauquer thinner) with a stiff brush then hot soap and water, maybe even boil the blocks in dish soap and water. Sounds like you may have a build up of the release graphite in there. You might try rubbing the cavities with a q tip see if it comes out gray black showing graphite remaining.

[runfiverun]

streaked voids sound like oil.
or like your getting a drip of lead in the cavity right before you pour.

[Dragonheart]

I suspect you have some contamination. I would scrub the mold with hot water and soap or with a good degreaser like "Oil Eater". Then I would give the mold a soak in acetone. Rubbing the cavities with a #2 pencil lead should eliminate sticking.

[Mr Peabody]

I think it's trapped air, fill the mould a little bit slower and see what happens.

[reddog81]

All my ideas were listed above - Too cold of a mold, too low a temp on the alloy, contamination, or trapped air.

Trapped air can happen if the vent lines get full of crud. Cleaning with a wooden toothpick or very gently with a box cutter can help.

[rr2241tx]

I have a similar issue with a high end mold that suddenly began making streaks. I sent it back and had it cleaned with the original cherry which fixed it temporarily but the streaks are back. Our best guess at the time was that there was zinc in the "certified alloy". The alloy was replaced and there has been no issue with any other mold since then. Still not sure what is causing this. I've cleaned with just about everything multiple times and the streaks won't stay gone. Picture for speculation:
http://i.imgur.com/e6bMGmM.jpg?1

[tomme boy]

Lube your pins. ALL of them, even the handle pins.