mold got rusted. Now what?

[nemesisenforcer]

Turns out our new place's shed decided to leak in the EXACT spot I kept my one unprotected steel mold, a new production Lyman 4 cavity.

It doesn't appear to be in the cavities but the outside and the vent holes are tarnished.

Is there a fix for this?

[Daddyfixit]

You might want to read this. http://schoepp.hylands.net/electrolyticrust.html
I have bead blasted molds before with good results.

[nemesisenforcer]

You might want to read this. http://schoepp.hylands.net/electrolyticrust.html
I have bead blasted molds before with good results.

where does one get bead blasting done?

[longbow]

Personally I would not bead blast. You are likely to get rounded edges.

There are products like Naval Jelly and others that will dissolve rust. If phosphoric acid based, they will also take of the heat blue but repeated use will restore that of cold blue will fix it too.

Electrolytic rust removal should work too but you can by rust removers from automotive parts stored and hardware stores. Cheap and easy.

When you say "...one unprotected mould..." I have to assume you either store them in sealed containers or oil them. I oil all my moulds after use, even brass and aluminum moulds because they have steel sprue plates and alignment pins. Steel rusts if left to its own devices and some moisture.

Anyway, sounds like you normally take care of them so I shouldn't lecture.

If the cavities aren't rusted then the mould should be fine. A little Naval Jelly or Evapo-Rust or similar should take it off the outside just fine. Once done though the mould will required oiling or at least sealing away from humidity until it forms a heat blue coating from use.

If the rust is really fine and only on the outside then I wouldn't even worry about myself. Use, then oil to protect. Next use, pre-heat until oil smokes then start casting. Oil after use again.

Longbow

[shoot-n-lead]

Most of the time, unless it has been left to rust for a long time, steel wool and oil will do the job. I typically spray mine after use, but in the past, I have failed to do that and found rust on the outside. I would just rub it with steel wool, spray and put away.

[Yodogsandman]

+1, using steel wool and oil.

[Gtek]

"Turns out our new place's shed decided to leak in the EXACT spot I kept my one unprotected steel mold"? Stay away from internal edges, removing sharps machined edge as stated above not good for nice boolits. OSPHO, bronze toothbrush, cold blue, Q-tips are my weapons of choice. All screws out, small cup, submerge for a couple minutes. Pull out and Q-tip first, brush if needed, cold blue with Q-tip and oil. If it did make to internal cavity, rub flat on face to edge of cavity. If in cavity, rub, rub, rub with Q-tips. I have a mold that looks like it washed up on the beach, drops good boolits.

[wallenba]

They sell a citrus based rust remover at Autozone. I think it has a good reputation. Or Home Depot this http://www.homedepot.com/p/Workshop-...0487/203247483

[Handloader109]

Stay away from naval jelly. Too concentrated and will etch. Evaporust is best if you have more than you want to remove with steel wool and oil. Won't harm metal at all. Harbor Freight has it, and some autoparts.

[goblism]

evaporust is the best, works quick but will remove the blue as well, just use it for a while to get the blue back

[Bohica793]

evaporust is the best, works quick but will remove the blue as well, just use it for a while to get the blue back

+1 for Evaporust. Restored a 100+ year old Winchester mold to casting perfection.

[osteodoc08]

Spray with oil of choice and steel wool as mentioned.

I really need to get some VPI paper and a plastic organizer.

[Petrol & Powder]

Rust is evil and I've done battle with it more than I wanted. Prevention is the key, once ferrous metal rusts you can never put that metal back on. If it's minor, you can remove the rust and go on. As Longbow stated, a lecture is not needed and besides, I've been there myself.
All of the previous posts cover the methods to remove rust. You want to remove the rust and do as little damage to the remaining good metal as possible.
As for prevention, molds poses a bit of a problem because oil/grease affects their operation. Some people can get away with dry storage methods. Because I live in a part of the world where you can watch unprotected ferrous metal rust, I err on the side of caution. If I intend to use the mold in the near future, I'll lightly coat it with Kroil. If the mold will be in storage for a while, I use RIG. Both of those methods require that the mold be degreased prior to use and the RIG is more difficult to remove but that's the price I pay.

[JonB_in_Glencoe]

Turns out our new place's shed decided to leak in the EXACT spot I kept my one unprotected steel mold, a new production Lyman 4 cavity.

It doesn't appear to be in the cavities but the outside and the vent holes are tarnished.

Is there a fix for this?

How bad is the rust ? a picture is worth a thousand words.

Yes prevention is the key.

BUT, if it's just a gentle haze of rust. No need to get all crazy with chemicals and steel wool.

I have a new ballisticast steel mold, it got a light haze of rust due to humidity and lack of protection. The mold was only used once, so it didn't have a patina built up to aid in rust prevention. I just coated the mold with kroil (my prefered penetrating oil) and rubbed the rusty haze with denim scraps...yes the cavities had some haze also...those got wiped with Q-tips, and NOT denim. Then cleaned the mold and I fired up the pot and cast with the mold. I preheat the mold with a hotplate. I cycled the mold to casting temp and back to room temp a few times to help a patina get started...I'm not sure what steel those kids used when they took over ballisticast last year, but it sure doesn't want a patina to build up...when I was finished that day, I coated it with kroil for storage.
Jon

[MT Gianni]

Get a #2 yellow pencil. Go over every inch with the pencil "lead". Cut the pencil off flush and go over the rest with the wood from the pencil. It should remove any surface rust and reveal any pitting.

[longbow]

I have used Naval Jelly on a variety of items with no problems at all. It may "etch" if left for extended periods but so far I have found no problems with any visible degradation of the steel item. The rust turns to mush then wipe off, rinse in water then dry and oil. I usually use heat to dry then oil while the item is good and warm.

No criticism of Evapo-Rust or others, just that Naval Jelly is generally readily available where some other products aren't... at least where I live.

[John Boy]

A 50:50 mix of ATF and Acetone. Soak it on - let it rest for a half hour and wipe with a bronze wool pad

[unclebill]

electrolysis?

[rintinglen]

Autozone and Pepboys carry Evaporust, which is my favorite. An over-night dunking in it followed by a good scrubbing with a stiff nylon brush and all surface rust will be abated. I never used to have problems with rust, but since moving closer to the Ocean, I have learned the hard way to oil my molds after use and to store them out of the nights air.

[FLHTC]

I've had rusted cavities and simply cut a slot in the base of the cast bullet, apply some Flitz metal polish, close it in the mold and work it back and fourth with a screwdriver. Kind of like the old boy scout method of starting a fire. Roll the screwdriver between your palms and in seconds, your cavities will look beautiful and the bullets will fall out when cast. As stated, steel wool will clean the outside but I've used granulated sugar in my sand blaster with excellent results.