First aid for rusty molds

[versifier]

I friend just came by after cleaning out someone's garage and dropped off two older Lyman molds: 356402 & 358495, and an Ohaus 501 38-158-R. [smilie=p: The cavities are OK, apart from a sipder web or two, but there is some surface rust on the blocks, outside and inside. I've never had to do first aid on one before as I take very good care of my own. How do I get them up and running without screwing them up? [smilie=1: Bronze wool? Input appreciated. :mrgreen:

[SharpsShooter]

A small brass brush wheel in a Dremel or like tool should work fine. If you use a light oil to loosen the corrosion, be sure to clean the mould with brake cleaner to de-grease.

[Denver]

I've cleaned up a mold or two by using muriatic acid and a Q tip. The acid I use is a mild solution from the hardware and is made for cleaning and etching metal prior to painting among other uses. I neutralize the acid when the rust is gone with baking soda and water. Wash and oil the blocks well afterwards and keep an eye on them to be sure no more rusting occurs from the acid.

[felix]

Phosphoric acid probably would be a better cleaner, but that would be much harder to obtain. Have a drugstore around that still makes cherry phosphate soda? Borrow some there. ... felix

[imashooter2]

Electrolytic rust removal:

http://www3.telus.net/public/aschoepp/electrolyticrust.html

[floodgate]

I friend just came by after cleaning out someone's garage and dropped off two older Lyman molds: 356402 & 358495, and an Ohaus 501 38-158-R. [smilie=p: The cavities are OK, apart from a sipder web or two, but there is some surface rust on the blocks, outside and inside. I've never had to do first aid on one before as I take very good care of my own. How do I get them up and running without screwing them up? [smilie=1: Bronze wool? Input appreciated. :mrgreen:

versifier (is you a POET???):

I've cleaned up a lot of rust on guns, moulds, etc., - just cleaned up a rusted loading press and a powder measure from the gun show this afternoon - and I can recommend brass or copper as a scraper or scrubber. Those brass "toothbrushes" you get at the Ace store, old bronze bore brushes (but use the ones with brass wire core, not steel), a squared off bit of K & S brass flat stock from the hobby store, even a fairly new penny. The bronze wool GAR used to sell is too crumbly, but others recommend the non-soapy bronze Chore Boy pads, too. Brass / bronze /copper won't scratch steel*, but will wear away rust (or lead), especially if doped with solvent or oil. An all-brass/bronze bore brush can be twirled in the cavity by hand or with a drill on low speed, and scrubbed across the vent lines. Works slow, but sure, and a swipe with Hoppe's** will take off any brass color left from the scrubbing.

floodgate

* But DON'T bang on steel with a brass hammer; it WILL dent the steel!

** And DON'T EVER use Hoppe's or anything else with ammonia in it on a nickeled finish; I ruined a fine old S&W that way - the more I scrubbed, the worse it looked (*sob*).

[versifier]

Thank you all for the suggestions, I'll get them running again as soon as I have a few minutes to play with them.
Floodgate, yes, I am. It's a tough job, but someone has to do it. :roll:

[Frank46]

Versifier, try naval jelly. One of its components is phosphoric acid. Should get rid of any light surface rust. But you will have to heat up the molds so's they turn blue from the heat to prevent further rusting. That is after they have been cleaned. Frank

[45 2.1]

Try soaking in vinegar several days.

[fecmech]

+1 on electrolytic removal ! I did a 4 cavity saeco mold a year or so ago that I thought was a total loss. It had been laying in a friends garage for a number of years and was heavily rusted all over including inside the cavities.. The mold cleaned up beautifully as only the rust is removed no other metal is affected. Made me a believer! Nick