Mould Oxidation And Rust

[sgabel1]

I purchased a new old stock Lyman mould 358212 that I am going to use for a Beretta 92 9mm that slugs .3575. A friend gave me some hard cast commercial fodder that leaded terrible. That being said I cast some and they were no where close to round. The base band was .360 across the seams and .355-.356 across the opposite. I contacted Lyman and they jerked me around telling me they had not sold that mold in years and they had no tooling and was on my own. I considered beagling but I wanted a more permanent solution. I found an article by someone on the LASC website about lapping moulds . Skip ahead 4-5 hours of work with multiple casts and 320 grit lapping compound and my cordless drill, the 2 cavity moulds dimensions around the diameter are now .359-.360 not bad for an amateur. My question now is the article mentions heat treating the mould to add the blue color back to prevent rust and oxidation. Is it heat treating that adds the blue color to the Lyman moulds or is the color really hot dip blueing? Any thoughts? I want to protect the hard work.

[Echo]

I believe the blue is formed by the heat of manufacture, and should be renewed in your lapped cavities simply by casting. I theeenk...

[462]

My experience has been that a mould will self-blue with casting temperature.

[Wally]

After it gets up to casting temperature you can use a propane torch to heat it a bit futher--keep the flame moving so you don't heat it for long in any one spot...heating the bullet cavities.

[stubert]

I would use the mold as is and don't give a second thought. I would be very wary about heating up a mold with a torch.

[mooman76]

I'd just use as is also. Just take care of it like your other equipment that might rust depending on where you live and the humidity levels. I basically have to do nothing here unless won't use something for a really really long time.

[Doc Highwall]

I have used them as polished and I have also warmed them up and applied cold blue either way will work.

[HORNET]

The heat bluing that Lyman does is no more that surface discoloration and might even be less effective as a corrosion inhibitor than cold bluing. Just run it as it is, several hours at casting temperature will probably restore some of the color. I have some old Ideal and Lyman molds that have more of a light yellow to the blocks that work just fine. I use an oil to prevent actual corrosion here in swamp country.

[casterofboolits]

Here in SW Ohio, humidity is a problem and it is a constant battle with rust on my iron moulds. It seems rust forms the instant the mould starts to cool. :groner:

Magma Eng. sells a preservative spray that does not need to be cleaned out before casting again. Next time I order lube, I'm going to order a can and try it out.

I'll post a report on how effective the spray is when I try it out.