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plating, anodizing, & finishing Q&As since 1989




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HELP! clear finish for gold plated parts that actually stays on and is durable

2003

I hope someone can help me with this. I restore antique high end banjos and crank phonographs, all of which were made between approximately 1890 and 1940. I have noticed a clear shellac/lacquer coating on the plated parts, especially the gold plated parts, applied during manufacturing, which seems to be durable enough to withstand most abrasions up to forcible screwdriver or putty knife scraping. In restorations of nice, old gold plate, I have tried to restore this finish when worn with an undercoat of sprayed shellac (which purportedly will stick tenaciously to anything, even wax) as a bonding primer, then my lacquer coats. In this process, even after about a year of curing, you can forcibly scratch off this coating with your fingernail, and I am pretty perturbed at that after all my efforts on several projects, and the fact that I never have this problem on other materials using the same procedure. I have read machinists books that say lacquer alone is enough to protect! bare brass, but how durable is that really? I am looking for a water clear or slightly amber product that will actually adhere to the metal parts and be very hard to scratch or abrade off, and be self leveling for a nice finish that preferably will not require a rubbing out or buffing to smooth out. Please, please, please, any help on my methods or any newer materials that could be suggested would help me immensely.

Thanks for any help!

Chris Cioffi
- Nashville, Tennessee, USA

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2003

Golden yellow lacquer for optical instruments:

alcohol(96%)-shellac solution.......450 gm
alcohol-dragons blood solution.....40 gm
alcohol safron/curcuma solution....20 gm
oil of lavender....................60 gm
oil of turpentine..................4 gm
boric acid (dissolved in water).....3 gm

May be sprayed or brushed! Instead this lacquer you can use 2o% shellac solution and picric acid as dye!

Goran Budija
- Cerovski vrh Croatia