Newly acquired mold doesn't respond well to pre-casting prep

[Maven]

All, I'm sure my pre-casting prep. with newly-acquired or new molds is similar to yours: Inspect, de-grease & preheat it, then smoke it with a wooden match, etc. Since that works most of the time, I tried it today with a double cav. Cramer 16H 146gr. (according to the data on Castpics) wadcutter that I got in excellent condition. After an hour or more of casting, I had maybe 15 usable CB's. The vast majority had rounded edges and frosting on one side of the casting in both cavities. Thinking I could improve upon this, I then sprayed the cavs. with dry graphite film: Wrong!! It only made matters worse. I even lapped the cavs. with fine & finer compound (the latter is "Pearl Drops" toothpaste) to remove all traces of the graphite. After cleaning & drying the mold, I heavily re-smoked it and tried casting again: Poor fill-out and frosting are all I got for my efforts. (Getting po'ed now & thinking of selling that dog!) Figuring I've nothing to lose by resorting to another trick to get balky molds to cooperate, I took a clean phosphor bronze bore brush and rotated it by hand in each cavity (Do this only on iron molds!) and lightly smoked each cavity. Voila! Most of its droppings were keepers, but accuracy has not yet been determined. This rather frustrating experience reminded me that neither smoking a mold (I have one LBT Al mold that doesn't tolerate any smoking at all.) nor coating it with graphite are panaceas (that word again!) and there can be too much of a good thing as well. Btw, the Cramer hums right along at 660-700 deg. v. 730-760deg. for most of my iron molds.

[David R]

I find a butane ligher works better than a match, they seem to have wax in the wood.

YMMV

David

[357tex]

Zippo works for me :grin:

[buck1]

""Poor fill-out and frosting ""
""dry graphite film: Wrong!! It only made matters worse""


Sounds like a venting problim to me. ....Buck

[44man]

I use Rapine mold prep in every mold and never have a problem. Check the ingredients in your graphite spray, might be some oil. Have you checked the vent lines? Sounds like the air is not getting out. You might also try hotter lead. If you use the bottom pour spout, try a ladle. If you use a ladle, try the bottom pour.
That mold might have to run a lot hotter too. Don't give up, every mold will work once you find the problem.

[Maven]

Let me clarify a few things. First, after removing both the graphite film and too heavy a coating of soot (from a wooden match), casting improved greatly. Second, the mold casts well enough @ ~700 deg., so that's not an issue. As for venting, I went over the vent lines [on the top surface of the mold] with a scriber made from a dental tool. If I can find a sharp, narrow file I'll go over them again as the reject rate is a bit higher than I'd like. Addiionally, the sprue plate is loose enough to swing freely. In the final analysis, the decision to keep or sell the thing will depend on how accurate its droppings are in my revolters.

[Willbird]

Maybe a past owner had some bear grease or something in the cavities ??


Bill

[Char-Gar]

I have over a half dozen Cramer molds of various vintages and have found them all to cast well. Some of the best molds around.

When I get an old used mold, I boil the blocks in a pan of water with some laundry detergent. I put the blocks (one at a time) in a metal colender and flush/rinse with clean boiling water. They will be hot enough to dry without any help. You never know what kind of oil/crap may have been placed there and soaked into those porus iron blocks. The boiling soapy water will open the pores and cut the grease and oil.

NEI Mold Prep on a Q-Tip is used in the cavities, on top of the blocks and the top and undersize of the spru cutter.

All that have received this treatment has cast well.