Care tips for brass mold

[alanf]

I am what would honestly be classified as rather junior when it comes to casting and just recently purchased my first brass mold an MP 314640 115gr.  Had my first casting session this weekend and realized I am not too sure how to keep the mold clean.  Following the guidance given on the MP site I cleaned and heat cycled the mold prior to its first go.  What care tips can you guys offer for keeping the mold free of lead splatter and tinning that occurs?  


Also, I struggled to get the bases to consistently fill out.  Any advice to improve this?

Thank you.

Alan

[wheelguns]

I preheat my molds on a hot plate. They take more heat than an aluminum mold. I would rather have it a little hot than not hot enough. I keep a rag that is damp with 2 cycle motor oil. When I cut the first sprue, with bullets still in the cavities, I use this rag to wipe the top of the mold and the bottom and top of the sprue plate. This will stop lead from sticking. To get the bases to fill out, make sure that you are pouring the lead fast enough, and are leaving a generous sprue. There are thousands of little tricks. Many of these are given on the mp website. They say it much better than me, but the best way is to cast bullets. If they don’t look right, throw them back in the pot, and keep trying. Before you know it, you will be an old pro with more molds than money.

[dhd]

Alan, I've got about 10 of the MP Molds with the same one as yours on the way. One thing I learned on the first one (and it hasn't changed with the rest) was the first casting session wasn't great, the second session was somewhat better, and the third session was awesome.

I've read where some have never even heard of tinning, but I have and watch for it like a hawk. A nice thing about a seasoned brass mold is you can wipe any hot spaltter or tinning off with a bamboo qtip. I also keep some burlap handy to wipe down any suspect area. Look at the mold hard before you stop for the session (I'll use my lighted magnifying glass) and get any build up off while the mold is hot. It's a royal PITA to remove when the mold is cold.

I suspect I'm to blame for my issues with tinning as the molds cast so good when they're hot that I keep on casting instead of slowing down. If I pace myself, I rarely see any build up. FWIW, it will be on the parting line of the cavities if you see any.

As far as getting lube on the sprue plate occasionally, I put some of the lube from the box on long bamboo qtips. After cutting the sprue I'll wipe the under side of the sprue plate and even over the surface of the mold. The lube doesn't cause any issues as the bullets are still in the cavities. Don't wipe the mold if no bullets are in the cavities or you'll cuss until it burns out. This is what I do always and it works for me. 

[alanf]

Thanks guys.

wheelguns - I too preheat with a hot plate. Will try the 2 cycle oil. I wonder if I got some sprue lube in the very edge of the cavities despite my best efforts to avoid it. My technique has some refining to go through.

dhd - I will check out the bamboo q-tips. Also need to locate some burlap.

[gamsek]

I learned that every problem I might had with MP brass HP mould was solved with 20minutes of preheating on a hot plate and alloy that has 770-780F, so ....do a slow pour but cast fast and don’t stop. First, second casting, results are so so despite all cleaning and prepping it (heat cycling it few times). Then after third casting magic happens.

Oil, as said above, start with dry mould / no oil, then when it’s hot, after few casts, just wipe it a bit with cotton rag which was treated with 2-3 drops of oil. After you cut the sprue, wipe top of the mould with bullets still in cavities, wipe bottom of sprue plate and touch the shafts of HP spins on outside....that way you will not contaminate cavities with oil. Less oil is better then more. Remember that you can start casting without lubricating it, but that rag on a hot mould will remove small lead particles under the sprue plate (in case you opened your sprue plate to early.)

I suggest just cast with mould, preheat well (sprue should solidify in 4-5 seconds) after it changes colour wait 2-3 seconds and cut the sprue. Tap tap on the handle hinge bolt, halves will start to open, flip the mould tap tap and shafts will slide out and release the bullets. Tap tap to help them fall or you can push the shafts and tap tap....

And all the shafts must move freely so they slide out and in under gravity alone. In this case you will not have problems closing the mould.

[gregs]

Take a pencil, and color hp pin and shafts that the various pins slide on to help them slide and release the fresh booolit off the pin.

Heat cycle at least three times.

As stated previously the first few sessions are not great but keep casting. I generally cast 100-150 the first time and might get 10-30 keepers. Until a patina develops tinning can be a problem. Have a rag handy and tooth pick to clear vent lines ect.

About the third time, the mold will hit its stride all of a sudden. This is when to make adjustments in sprue plate tightness and casting tempo, speed and style. Sometimes you have to pressure pour to get good fillout.

Once my molds are working, I can generally run at 710 to 730. If I have a pesky mold, I can always raise it but in general, I can get away around 715 and cast fast without getting frosting.

Molds are like a woman. They are all different and have individual pet peeves. Get her broken in and find out what makes her rain beautiful bullets.