Tuesday, December 10, 2013

Stripping Zinc & Sandblasting Hardware

This is an area that chewed up a lot of time. Larger parts are easy to hold and clean up in a sand blaster but small parts were a challenge. All zinc must be removed before CAD plating parts or it will not stick. I have a small blasting cabined that has 50 micron glass beads in it. I tried to remove the zinc with this but it was slow going. I researched “zinc removal” on Google and found that pure lye mixed with water will dissolve zinc. The only local source of pure lye was a product sold at our Lowes hardware store called “Roebic Crystal Drain Opener”.  I purchase a small can of this and set about dissolving zinc.

When water is added to the lye the bolts will smoke under water. If this does not occur more lye must be added. They came out of the solution with a black oxide coating them. After the zinc was removed I bead blasted all parts to bare metal. The most difficult part about blasting was holding everything. I will need to come up with a better system next time. 

Caution: I assume fumes from zinc removal to be toxic. Do not breathe or do this process inside. I assume leftover solution is also toxic. I recommend disposing of it at a hazardous waste collection site. (common in the US). 

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