Mp Mold prep:

[Whitetailsniperkirk]

I have question I hope I’m in right place to post it. On the new mp molds out of brass,
Before useing for first time casting session, should I clean the molds and pins with dawn dish soap ? Or anything else before casting with them?? I have 3 brass molds from miha( mp molds) .

[Walks]

Yep.
Dawn first, heat cycle 4 times. Then brake cleaner just before you start to cast.

[AlHunt]

Yep.
Dawn first, heat cycle 4 times. Then brake cleaner just before you start to cast.

But not just ANY Brake Cleaner! Use the non-chlorinated stuff. The chlorinated stuff leaves a residue.

Straight acetone works, too.

[Targa]

Brush and acetone does the trick for my molds. Heat cycle a few times, lube your typical points, color those pins with a soft lead pencil.

[DHDeal]

Don't be bothered that your first session (and less so on the second session) doesn't give you all perfect bullets. I'll get great bullets on the first session, but not the first few drops. I've cleaned, heat cycled, and preheated my new MP Molds and still need to get some lead through them before perfection starts. The second session (but for sure the third session) gives me great bullets from the first drop if the mold is preheated. Preheating on a hotplate is as important as proper lead temp for me getting great bullets from the first drop on a mold (after a mold is conditioned that is).

In my case a MP Mold that is dropping winners can get me in trouble. I'll want to fill up that bullet tray and will speed up. I have run into tinning from getting the mold screaming hot. I've learned to stay at a certain pace and watching for any smears on the mold faces. If I see any I'll wipe the faces with either a piece of burlap or use a carpenters pencil to get it off. After I started pacing myself, I've rarely seen any tinning. But these molds cast so easy it's hard to slow down....

[JonB_in_Glencoe]

Brass molds are susceptible to getting "tinned" alloy on the mold face, especially on virgin unoxidized molds.
The heat cycling (have mold open) will start to make a oxidized layer (patina), even if you can't see it, it's there and acts like a mold release and keeps alloy from tinning onto the mold face.
So, do not over look doing 3 or 4 heat cycles before casting
that's my 2¢

[gwpercle]

I prefer to clean cavities with acetone and an old Oral-B toothbrush ( they don't melt) to remove cutting oils . No better de-greaser ... look in Wally Mart paint dept .
Very important to heat cycle , clean and do this 3 or 4 times .
Heating / cooling drives out cutting oils , acetone removes all traces of oil and heat cycling "seasons" the mould cavity surfaces ... aka build up an oxidized layer . Don't skip this step !
Gary

[Dimner]

For my 2 MP Brass molds...

I first cleaned with warm-hot water and dawn dish soap. Towel dried.

Then I heat cycled them on my hot plate. The first heat cycle will also dry your mold from your washing if you missed any bits of water.

When you heat cycle them on the hotplate.... Make sure the mold blocks are open, heat up to casting temp. I usually hold that temp for an hour, but I'm not sure if that is necessary. Then turn off the hotplate and let the mold cool down naturally until room temp (while still on the hotplate). It will take a while, but this is the key part for getting a bit of 'patina' or whatever on the mold. Do this 3 times, 4 is better. Use an old lamp timer if you want to do it hands off.

After heat cycling, apply your preferred mold lube as you normally would.

I found out the hard way and used my first MP brass mold without heat cycling. I ended up with lots of bullets that did not want to fall out of the mold. I had to smack it far too many times with the mallet. Also ended up with some sprue smears on the top of the mold blocks.

Starting over from scratch heat cycling my mold made all the difference. On my 2nd mold, I heat cycled from the get go, and have not had any problems.

[GregLaROCHE]

I normally clean used and new molds with break cleaner first and then warm water and dish soap. With a new steel or aluminum mold, I would start casting, but not expecting to get the best boolits until after a few cycles.

However with a new brass mold, I would clean it and cycle it a few times in an oven or on a hot plate, before pouring alloy into it. A little more time to be sure.

[Capt.Red.44]

Great advice. With a HP Mold, whats the best way to position the mold on the hotplate? I was using the handles up method but couldnt seem to get the mold evenly heated. Are you doing the heat cycling without handles attached and with pins removed? I have several new brass molds on the way, all HP Brass molds. Arsenal, MP and NOE

[JonB_in_Glencoe]

w/ handles, just like I was preheating to be casting.
when I cut the heat, I will gently blow air onto the cavity area.