So this friend of mine said he had some old molds...

[kodiak6579]

Technically it was my best friends father, but I consider him a friend as well. Anyway he heard that I got into casting and let me borrow a couple of molds. The problem is that last winter the boiler in his basement let go and was shooting steam into the basement for about a week :groner:. As you can see in the photo, a couple of them look pretty gnarly. Sorry about the photo quality... I'm not too worried about the top left (aluminium), top center (aluminum) or the bottom left (steel but in OK shape), but the two on the right are fairly bad off. There's also an ingot mold (not in the photo) that should be pretty easy to clean up. I was wondering if there was any tips or tricks you all know for rehabing molds? If so I'm all ears! Thanks guys!

[GP100man]

looks as if 0000steel wool should do it ,did`nt see any pittin yet.

wrap the wool around brush close the mold on brush & spin it slowly.

or do the electrolysis thing .

[mikesdad]

have them blasted with walnut shell or plastic media. check for sand balstes in yellow pages or someone that restores cars, particularly corvettes. both are soft enough they wond do harm but will clean well. test the aluminimum for possible erosion by the walnut shell first, to be safe.

[cajun shooter]

About 9 months ago I read about this product called EVAPO-Rust that is sold by Midway or Brownell's. I will have to look and see were I bought it. It sells for about $18 or so dollars a gallon. It's the most amazing product that I've ever used. I poured about a pint into a small plastic container and inserted a mold that was far worse than the ones you have shown. In 2 hours I pulled it from the container and it looked like new. Unreal!! You can keep using the same solution until it turns black. I'm still using that first container. You don't put it back into the new stuff. I put a slide and bbl into it about 4 days ago . The bbl was rusted and stuck in the slide. I let it set overnite and the next day it was like new again. Oh and it 's not a eat your hands up stuff either. You can put your hands in it which I've done and it does no harm. It's 100% better than trying to scrub little tiny places with steel wool. Later David

[Blammer]

get a pencil

take the pencil part and 'write' or 'scribble' on the inside of the cavity completely.

then take the eraser part and erase it all.

rust should be gone. :)

[38-55]

Yeah what blammer said...
Another little trick.. try rubbing/scraping the rust with a nickel.. it takes the rust right off and will even leaving blueing intact.. Really none of those molds look beyond hope.. I have an old bag mold ( It was pulled out of a wall in an old house house wrapped in a newspaper from 1862 ) that was rusted beyond belief.. I cleaned it up and still cast the occasional .36 round ball with it..
Hope this helps ya some and good luck !
Calvin
PS what are the iron molds ?

[kodiak6579]

A pencil?! Really? Allright, I'll give it a shot. Thanks for all the tips... And the iron molds are all .30 cals of various weights. Also i think i may give EVAPO-RUST a shot. Hey, GP, how do you do the "electrolysis thing"? Thanks All!

[quietmike]

DIY-Electrolysis

http://www.antique-engines.com/electrol.asp

[JIMinPHX]

Rubbing them with wadded up aluminum foil sometimes helps too.

[imashooter2]

Electrolytic rust removal is really a terrific thing for molds. It removes only the rust and it can't harm the base metal at all.

A quick and easy set up I have used several times:

http://home.comcast.net/~imashooter2/pictures/ERR-out.jpg

http://home.comcast.net/~imashooter2/pictures/ERR-in.jpg

The trickle charger shown works over 24 - 48 hours. A 10 amp charger, overnight. The higher the amperage on the charger the faster it works, but the wires will need to be larger and the solution boils off so needs to be watched. Use a big enough container.

[montana_charlie]

http://www.evaporust.com/evaporust.html

[hammerhead357]

I have used 0000 steel wool wrapped around a match stick sized piece of wood and turned very slowly with a varibile speed drill in each half of a mould to remove rust with no damage to the mould but I was very careful and went at it slowly and one cavity at a time. The steel wool will conform to the shape of the cavity and get out the rust. I did not close the mould on the steel wool I only did one side of the mould at a time and then the other.
In fact I have used kitchen match sticks to do this. They will break if you get to heavy handed with them. I have used this method to get the light rust out of some of my 8 and 10 cavity H & G moulds when the roof was blown off of my shop at one time....Wes