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Student Question: Uses or sources of boric acid, fluorine, and barium sulfide

If anybody can give me some info., I'm doing a research assignment on plating and coating. I am the mock CEO of a mock plating and coatings company, and my instructor has given me a list of chemicals to do a waste minimization report on. I have been unable to find the uses of some of the chemicals in the industry. The chemicals are boric acid ⇦this on eBay or Amazon [affil links] , fluorine, and barium sulfide. Any info on the uses of these chemicals would be appreciated. thanks,

Jake hairell
- spring, texas
1999

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Boric acid is kept in the bathroom medicine cabinets of plating shops as an eyewash. Putting smaller eyedroppers in the bottles might help reduce waste, not just in plating shops, but in the school nurse's office as well :-)

Boric acid is also used as a buffer in acid plating baths. Elemental fluorine is not used, but hydrofluoric acid and fluoboric acids and acid salts are widely used. Sorry, I'm not familiar with barium sulfide.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Boric acid is a wonderful buffer for plating baths. H⁺ ion is frequently removed from the diffusion zone which is possibly a millionth of an inch thick on the part that you are plating. This raises the pH and forms a ugly or bad or both plate in acid plating solutions (baths). Boric acid has 3 hydrogen ions that will come out as required to maintain a pH on the surface. They come out at 3 different pH's, so are wonderfully useful in lots of different plating solutions. It has a tendency to make the plate white or bright, this is because it maintains the pH very well. Higher pH's tend to give a dark or even black look that is sometimes rough. A buffer is a chemical that will resist the change of a pH in either direction.

Fluorine is a gas that is extremely active and very dangerous. "Fluorides" are in plating in etch/activation tanks and a few plating bath. Fluoboric acid is much more common in plating baths. Ammonium bi fluoride is the safest way to get the fluoride ion as hydrofluoric acid is very dangerous, possibly the nastiest acid to work with in a concentrated state. It eats glass!

I can not imagine a use for barium sulfide as barium forms rather insoluble compounds as does sulfides. Barium sulfide should be extremely insoluble. Both are hazardous materials and require special handling, more so than than some other plating materials.

James Watts
- Navarre, Florida
1999

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Barium sulfide can be used for putting blue and brown coatings, or patinas, on metals like brass, bronze, and copper.

Dave Wichern
Consultant - The Bronx, New York
1999