Using oil or grease to lubricate your molds came up on another post so I thought it might be a good time to post how I cast to keep from contaminating my bullets to be powder coated. Many use some type of lubricant on their molds and for years I used synthetic 2 cycle motor oil on the sprue screw, which I thought to be the best solution. But the simple fact is if you put oil or grease on you mold it will flow and has a way of finding itself into the cavities creating casting problems and possibly contaminating bullets to be powder coated. As most are aware contaminated bullets and powder coating just don't mix. If oil getting in to where you don't want it has never happened to you then you are just lucky or haven't been casting long enough.
I now avoid the contamination problem by using dry graphite on my mold surfaces including the mold cavities. Over the years I have often posted using the lead from a #2 pencil to coat the bullet cavities to eliminate sticking bullets. Using the graphite from a pencil also works on the mating mold surfaces and on the top of the blocks and the underside of the sprue cutter. The graphite provides sufficient lubrication as well as an aid to keep alloy from sticking to the surfaces. The graphite does not effect the mating surfaces or the size of the bullet.
I use standard writing pencils and/or carpenter's pencils to simply rub a solid coating of graphite on the surfaces of a completely clean and free of any lead mold. I then brush off the surfaces with a clean toothbrush that is only used for that purpose. A little time consuming, but nothing like having to stop to clean lead smears and restart the process.
Additionally , I run two 4 cavity molds simultaneously. By alternating the molds, one mold is cooling while the other is opened and re-poured. Using this method I cannot be tempted to cut the sprue too soon and smearing lead on the underside of the cutter and top of the mold blocks. By alternating I consistently produce 20 bullets a minute and depending on bullet size empty my 20# Pro Melt in approximately 25 minutes.
The attached photos shows the surfaces of my H&G #7 mold after a run in excess of 1200 bullets yesterday in this mold alone; Note the lack of lead spots or build up on the surfaces and you can still see the graphite coating. The graphite can be touched up if needed while waiting for a fresh pot of metal to heat up. This was one of the two molds I used yesterday; the other a H&G #68, also shows the lack of lead spots or smears. I have used this technique on my brass and aluminum molds also, but I only own a couple of seldom used aluminum molds.
Maybe this will work for you as well.