preheating brass molds?

[Strtspdlx]

normally I preheat my molds with a hot plate I bought specifically for preheating, with my aluminum molds I run it just below the hottest setting until my pot reaches casting temp, which is between 750 and 800 depending on mold. Ive noticed with my brass molds the hot plate on the hottest setting doesn't get them to temp fast enough so I end up casting for awhile (maybe 50-80 bullets depending on mold) before it drops good bullets, I could leave it on the hot plate longer but its convenient to run them both until the pot is ready and go to work. The two I have most of the issues with or HP molds. it could just be the pins and I haven't tried heating slightly with a torch. I was mainly curious to see what everyone else is doing. I know there are multiple threads but id like to stick to the idea that when to pot is ready the mold should be also.

[Reddirt62]

I also use a hot plate but I flip a bread pan upside down on top to hold in the heat....still takes some time.

Sent from my SM-N920V using Tapatalk

[OS OK]

Attachment 202128

A cover might help but you may need a more powerful hotplate...I think they come in two wattages, one of them several hundred watts more powerful than the other.
Mine, I think is a 1,200 watt unit and I hardly ever turn it up over 1/2 way although I've only used steel or aluminum moulds so far.
I have a 4C HP mould coming in brass so that'll be a first for me too, we'll see pretty soon.

[country gent]

I cast on a plumbers style pot I made. I use a weed burner for the heat source (500,000 btu model) the pot is 100+lbs. I made a rack of along side the pot and set the first 2 moulds on it against the pots side where one of the vent hole are while the pot comes up to temp. Once pot is hot and up to temp the brass moukds are up to tem maybe a little to warm as they take a little longer for sprue to cool. If I'm casting with more than 2 moukds during the session I cast to with in 75-100 of what I want with the first 2 and set the second 2 on the rack to warm after the run with the first 2 is done I have the next 2 ready to go. One plus or drawback to brass is it heats very evenly distributing the heat thru the blocks this means more heat is needed to bring all the mass up to temp. You might try rolling the mould occasionally from top to bottom while pre heating. This will help even out the heat

[wv109323]

I have found with brass molds open them slightly to let the heat flow up through them. It will also get the sprue plate hot. I find a cold sprue plate keeps you from making good bullets with a brass mold. They heat at different rates.

[Strtspdlx]

I did start flipping it. And I agree that a hot sprue plate is vital for a brass mold. flipping the mold it has helped alot but I'm still casting a tleast 10 throws before it works well enough to keep them. I'm used to my non brass molds that I can get good bullets from from the first pour.