mould prep

[giddyupgo55]

I'v been reading about prepping (?) the mould before use. What is required in doing this? The moulds are used but I don't want to mess them up.

[Tom Herman]

Welcome!

There are two things that I do to prepare molds: The ones I use are Lyman, and what I do is carefully file the edges of the sprue plate, so that the edges are smooth as they drag across the mold.
I start with a fine file, then use 400 grit sand paper to take out the last scratches, and finish with 1500 grit to give the edges a nice polish.
I also do this to the top side where the sprue plate rides into the screw that captures it when it's closed.
Almost without exception, the edges have scratched my molds before I caught it.
I sometimes find bumps, dings, and sand particles on the sprue plate that will scratch the top of the mold.
Once I'm done getting the edges, I'll reassemble to sprue plate to the mold, put on the handles, and swing it open and closed to make sure I haven't missed anything. Don't be surprised if you have to pull it apart several times to get the last imperfections out.
You will also need to degrease the mold before using: I use a brake or carburetor cleaner. Some people boil with detergent, then rinse clean & blast off the water with an air hose.
I also preheat the mold on the stove (about 2-3 setting) before casting.
Good Luck!

Happy Shootin'! -Tom

[Slow Elk 45/70]

Hullo Giddyupgo, and welcome.

Most used molds that are purchased at auction or elsewhere need to be inspected
and cleaned. I inspect them, looking for burs and clogged vent lines. If they are present, clean them up carefully with an exacto knife and or a fine file/ emery cloth.

I like to degrease the molds with mineral spirits/paint thinner, soak for 12-24 hours and then clean with liquid soap and boiling water, dry and apply Bull Plate to the top of the mold and sprute plate and the pins. Don't get it into the cavities.

If you have issues after this, there are remedies for such as boolits not dropping freely etc. in the stickies and threads here on site or explain your problem and someone will help you, I'm sure. Good luck

[giddyupgo55]

Thanks for info guys I'll make sure everything is real clean before starting

[Shiloh]

I clean new ones or acquired used ones with mineral spirits, then carb cleaner or acetone, finally chased by a good scrubbing with Mr. Clean or other household cleaner. Scrub or toothbrush to clean really good. Rinse in very hot water, dry and you're good to go.

If the boolits don't drop or stick try smoking the cavities with a butane lighter.
Bullplate lube on the sprue plate cuts sprues like a hot nife through soft butter.

Shiloh