walnut shell blasting

[Hoppy]

Over the weekend I tried to remove some old paint from some cast aluminum parts. Each of the parts has several machined surfaces so I used walnut shell in a small blasting cabinet. The paint came right off, but I ended up depositing a thick layer of some light-tan colored stuff on the parts. The layer is thick and hard as rock. It won't come off with a stiff brush or by soaking. It will crack if I smack it a few times with a ball pein hammer, but even then not all of if will come off.

Where did this stuff come from and how can I get rid of it?

 

[abarnsley]

Several large Helicopters have been crashed due to Walnut shell residue clogging oil passages, now banned for Army aircraft use...

Reblast with glass beads...

might try boiling in soapy water...

 

[Jeff_G]

I don't know about the shells or any oils they may contain, but sawdust from walnut lumber is mildly toxic. Ask your supplier for the Material Safety Data Sheet (MSDS).

 

[jimbo1490]

We had tentatively adopted this technology back in the '80s and early '90's as we were told that chemical strippers would be done away with in a few years. We tried the walnut shells, plastic blast media and finally baking soda. All of them 'worked' so to speak in that they removed paint. We even had the dry ice blaster guys come out and demo a job for us. But the cost per unit area was way high for all these blast setups, especially the dry ice deal which was around $250/hour, IIRC. And then in the early 90's, new generations of chemical removers came onto the market, which were environmentally (and personally) much safer. They take off the paint reasonably quickly and very cheaply, especially when environmental disposal is taken into account. We sold off all that blasting stuff about 12 years ago and never looked back. Aluminum is especially easy to strip chemically since you can use acid activated strippers. Steel, especially high strength steel, does not get along with acid strippers, whether environmentally friendly formula or not.

Jimbo

 

[Kallam]

Thats bondo they use it to fill inperfections in castings.