Where theworld gathers for metal finishing
Q&As since 1989
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Restore dark doorknobs; don't know if solid brass or not
Q. Goran: How do you know when you're at 9%? Thanks.
J Nan- West Chester
June 4, 2023
pH Paper
on
eBay
or
Amazon
(affil links)
A. Hi J. It's not 9%, it's pH 9. You can use pH paper to determine the pH.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. You must use pH paper. Add some ammonia
[on
eBay or
Amazon] (25%) to 50 gms citric acid/ 1 lit water solution (10 mll for example), test it with pH paper, add some ammonia again if needs and so on util pH is 9.
Hope it helps and good luck!
- Zagreb; Croatia
June 5, 2023
⇩ Closely related postings, oldest first ⇩
Q. My house was built in 1907, with some fine details. I recently polished a gooky old lamp bracket to discover a lovely brass glow beneath. Now I'm wondering about the doorknobs. My husband believes that their dark exterior is a matte finish; I think it's 97 years of grime etc. We've started playing with them; I soaked in a mixture of vinegar [in bulk on eBay or Amazon] & baking soda [on eBay or Amazon] , which began to reveal what looks like a copper color. Did a bit of polishing with Brasso [on eBay or Amazon], but not getting very far. Should I keep going or is this a mistake?
Marion Rogershomeowner - Guelph, Ontario, Canada
2004
A. Try a magnet. If they are magnetic, they are plated iron or steel and you may be worsening things. If they are non-magnetic, and they really date to 1907, I think it is very likely that they are brass and that they can be restored to a brass color.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. If your knobs are brass you can use 5% solution of ammonium citrate (pH9)! This is mixture of 50 gms citric acid [on
eBay or
Amazon] /1 lit water, and some ammonia (25%) must be added (to reach pH 9). You can use cold or hot solution (80 °C). In case of brass plated iron you can use 5% citric acid solution, or ammonium citrate 5%, but pH must be 3,5. Rinse well. Think about some good clearcoat.
Good luck!
- Cerovski vrh Croatia
Q. I was very eager to try this as I have an amazing vintage brass ashtray that has gone a little pink after Brasso [on eBay or Amazon], but even with the ammonia citric acid water mixture, it's not changing -- any suggestions?
Vanessa perkinsHobbyist - Toronto Canada
February 8, 2022
A. Ammonium citrate (50 gms citric acid , add some ammonia 25%, pH must be 9) can be used hot (80 °C temp.) Prolonged immersion in cold solution can be helpful too.
Hope it helps and good luck
- Cerovski vrh Croatia
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