So,,,,

Sandblasting cast iron, 3rd member, 4 speed case, parts, front spindles, caliper mounts, etc, etc, etc, how do you keep the cast iron looking like cast iron after its blasted?

Do you spray it with something?

I have had good luck using Evaporust.

Here is a 4spd main case that was soaked in it for a day (it was degreased first) and the stencils/paint daubs magically reappeared!

Read here with pictures, descriptions, techniques: https://board.moparts.org/ubbthreads/show...&PHPSESSID=

Honestly, if you sand/bead blast the cast iron, you are going to change the color and characteristics of it. As the second poster mentioned, I have had EXCELLENT results with Evaporust and have had the inspection marks and such show up better and the rust totally desolved. One thing to remember is to make sure it is completely cleaned off as the Evaporust will not remove the grease, just rust.

Look at the dates on the thread linked above. Those were great methods and techniques back then, and while some still have merit and can produce a nice looking part, those methods are really obsolete due to new products that have hit the market in the past several years.

Here's what I'd reccomend for the most accurate factory correct appearance.


Clean the part (I use a STRONG degreaser and then steam cleaning).

Soak it in Evaporust overnight, a 5 gallon bucket will cost about $80.00 and will be large enough to soak a trans case, it's reusable so you won't be spending $80.00 just to do the case.

Wash off the Evaporust with Laquer thinner NOT WATER!

Use a Scotch Brite pad to scrub off any remaining residue, be careful around inspection marks so you can save them.

Give it another soak in Evaporust overnight

Clean it again with a Scotchbright pad

One good last wash down with Thinner

Now warm the case to about 160 degrees with a heat gun and brush on a complete coating of RPM (one $35.00 jar of this stuff will treat all the bare metal on an entire car) ECS Website Learn More Here
This product does not convert rust so it's important to get ALL of the rust off before applying it, it simply keeps new rust from forming, once it dries and is buffed off with a cloth it's not sticky and is invisible.
You will be stunned at how well it look and holds up.

you wont want to apply the RPM over the cosmoline, I guess you would be able to go vice-versa to have the cosmoline appearence on the treated part.

I didn't know about the Laquer thinner to wash off the EvapoRust. Thanks for the tip. Since EvapoRust loses strength fairly quickly(and because I learned about it late in the game) I did blast some parts and it does change the color. For those parts I darkened them with black oxide solution before using the RPM. They are not perfect but I think they look better then paint. Since yours is already blasted, it's worth a try.

Here is the center section that was blasted, then darked with black oxide and finally RPM'd. I think it looks better then paint.

Thanks guys!

Great info

In my experieince cast iron can take on many color shades depending on how it is cleaned. If you blast it you are basically opening up the surface and can cause tiny peaks and valleys in the metal that were not there before. Adding these new surfaces reflects more light and can make the part look brighter than it did when new. When you coat the part in a product like RPM the coating can knock back the relfectivity of the parts surface and make it appear darker than when freshly blasted. However, if you consider that the freshly blasted part was likely too bright, this slight darkening effect is a good thing, it can bring it back to a shade that is more correct. By comparison, if you treat a fresh new part or an NOS part with RPM, one that has never been blasted, just degreased and cleaned with thinner, etc. you will not see much if any difference at all.

If you are looking for a good container to soak a Trans main case try a plastic 5 gallon paint bucket. Keep in mind that Evaporust can leave a black film on the part, this slimy film is the rust that has been neautralized, actually converted to what is basically carbon (like wet soot) when Evaporust is to the point of not working the fluid, which starts out the color of Mountain Dew, will look as black as ink. If you only partially dip a part in Evaporust it can leave a "waterline" of this carbon that takes a bit of scrubbing to remove so it's best to completely submerge the part. It's a good idea to have 2 containers of Evaporust, one for processing the heavy rust, and one that you keep as fresh as possible to use as a cleanup to get the last 10% or so of remaining rust off, this keeps the carbon slime content to a minimum in your "clean" bucket so that it doesn't stick to your mostly clean parts.

If you are doing multiple cleanup projects like an entire suspension, rear end, drive shaft, etc. you will likely spend a few hundred dollars on Evaporust to get the entire job done, but in the scope of a big proect it's not that expensive considering how well it works.

BTW, if you are shooting for a true original appearance and are looking for REAL Cosmoline, you can still buy it. I just got some here Cosmoline Source