You need to decide how big of material you are going to blast My buddy has a 36" box - carbs and small bits are OK, wheels are no go It cleans and refurbishes metal, plastic and rubber bits Plus, it's water based, so clean up of the medium means dunking it in a bucket of water and drying with the air gun
The ones that I have looked at are just blast cabinets with a solution of abrasive media (sand or glass beads) carried in a high-pressure stream of water. The resulting finish is very nice for restoration of old bikes and cars, but I would not use it for cleaning coated surfaces like most modern die-cast cases. It still uses an abrasive material that must be totally flushed out of everywhere in the component before you build the motor. I had one client who sent all of his BMW R90S cases to England to be "Vapor Honed". The vendor promised that absolutely no abrasive was used, and that the cases would be returned in "ready to assemble" condition. Then the client took the parts to a BMW tech who assembled the whole thing while in an alcoholic haze, not bothering to actually look at the stuff and SEE that there was grit in everything. The motor lasted less than 200 miles. Destroyed the pistons, crank, cylinders, rods, oil pump, etc., ad infinitum. At that point the client comes to me and says "What happened?" I flushed out more than five ounces of grit, and that was AFTER two oil changes on the motor. Lesson: If it cleans and restores the finish, you gotta clean it up. I've tried soda blasting, too, but soda becomes very corrosive when it gets in contact with moisture, so the post-blasting cleanup is just as important. Plus you have to neutralize the caustic soda. I'm actually on the verge of buying a "vapor-blast" cabinet setup, because it will return the original finish I want for old BMW cases, but I will know that I have to strip and flush every part.
What's the best way to neutralize the soda? I plan on soda blasting some engine cases and was going to thoughly rinse them with water and then dry them with compressed air prior to paint.
There is a blasting process that uses CO2 (dry ice) and leaves no residue. Obvious issues with extreme cold media, and suffocation should be considered.
I am aware of blasting grit cleaning. I am looking at getting a vapor hone. The plus over dry blasting as they say is the media is in solution so you do not get the embedding of the media in the alu. and the cleaning action is more scouring than impaction. I just wondered if anyone has used one to confirm the cleaning action does not embed media. I get it will be in every bolt hole or oil passage. I like soda blasting for those areas.
I immersed all parts in a tub with hot water flowing through it (hose from hot water heater) for about a half hour, then blew them dry with compressed air in every thread and passageway. Next I doused everything with WD-40, let it sit overnight and washed it all again in the parts washer. That's a LOT of labor. When I got done the cases looked wrong, and corrosion crystals grew in some of the threaded holes anyhow. What a total pain in the ass. The only benefit to soda basting is also the greatest problem: the soda is one-use media, so you are always feeding from a fresh supply that has very consistent "tooth". The downside is that soda blasting media is pretty expensive. I used Arm&Hammer Armex Flow XL, but they have lots of choices. I experimented with some of their other grits. None of them returned the OEM factory finish I wanted. So far, Vapor Honing with wet media is the only one that returns the exact finish on BMW cast aluminum engine and gearbox cases that I want. CO2 blasting has a lot of downside: 1) Very expensive equipment compared to other methods, 2) Extreme cold can cause chill fractures on thin parts, 3) The CO2 vapors in your shop will condense into some caustic shit in every corner. 4) While the CO2 itself leaves no residue, whatever you blast does leave residue that still has to be cleaned, so it is not a true "clean" process.
Hit me up in a month and I will have the answer to your questions. I am getting a machine on test loan.
Isn't caustic soda just another name for lye? I'm not a chemist nor did I sleep at a Holiday Inn Express last night but I'd neutralize that with vinegar or some other mild acid. Enough water would eventually wash the soda away but it'd form a very, very corrosive liquid until that point.
The media does not embed in the metal. It micro peens the aluminum surface and lowers the oxidation rate, keeping it new looking for a long time. Clean up is easy. Pull it out and dip in a bucket of water and swirl it around, the blow dry with the air hose. I've been doing smaller pieces, like carbs. For a bigger piece, bucket of soap/water for initial cleaning will keep the media in suspension to make it easier to rinse off. I've under cleaned a few pieces. Shot them again to get the media back in suspension and recleaned no problem
Thanks for the info. So far I've only used it to clean the paint and old gasket material off of a few small valve covers prior to repainting and the results for this purpose were good. I've actually been using generic supermarket baking soda as my test medium, but just got a 50lb bag of Armex XL Maintenance Formula for the rest of the job. I'll make extra sure to keep on rinsing off all the residue till it's gone for the rest of the job.
Soda blasting uses food grade baking soda. Quite safe stuff to work with and convenient for a part time hack like me who only needs to blast the occasional small job. With the right set up it can be used for larger jobs too. The Statue of Liberty was soda blasted when they were restoring her.
