# How to blacken a zinc bolt



## bsingin64 (Apr 30, 2010)

I couldn't find any black oxide bolts at my Big Orange Box store, and I was late for dinner, so I picked up zinc carriage bolts instead. Now I need to find a way to blacken them. I hoped it would be as easy as taking a torch to them, but it only lost the sheen of the zinc, but was deffinately still silver in color.

Any suggestions?

I know officially i need caustic soda to make black oxide…. i cant say I have any laying around…. so anyone know how to make / come up with it / another way to make my bolts black?

Thanks so much community. I'll post pics of the bench when its done.


----------



## Dark_Lightning (Nov 20, 2009)

Do not heat zinc in a closed space with a torch. The fumes can be lethal. Be careful in open air for that matter. You probably just vaporized the zinc off, leaving the raw steel below exposed. No joke.

If you look again, I'm sure I have seen black carriage bolts, but they were probably lead-filled black paint from China. Don't heat those, either, if there is lead in the paint.


----------



## MedicKen (Dec 2, 2008)

Vinegar and steel wool in a bottle. Mix the 2 together and put the bols in the solution and let it set. Be patient


----------



## bsingin64 (Apr 30, 2010)

Its probably what happened when i torched it… Poof after about 20 seconds of heat, the zinc vaporized. I've played with pennies doing that too… fun stuff making hollow pennies….

So now that I have bare steel, i still need it black…. and a sharpie isnt my favorite solution.


----------



## bsingin64 (Apr 30, 2010)

Thanks medicKen. i'll give it a shot right now… how long do you think it will take for that to work? and Should I start by removing the zinc - ala Torch?


----------



## MedicKen (Dec 2, 2008)

I will most likely take a few days. You can also use the same solution to ebonize wood


----------



## bsingin64 (Apr 30, 2010)

thats the first time I've ever heard the word ebonize, so I looked it up. What a great piece of education. I think I'll have fun with that. Thanks


----------



## Knothead62 (Apr 17, 2010)

Go outside, heat it a bit and drop it in a metal can with motor oil. I watched a gunsmith do this with gun parts. Came out with a nice finish.


----------



## bsingin64 (Apr 30, 2010)

well the vinegar and steel wool did the trick. It put a nice layer of rust all over the threads that were above the vinegar's surface and set a decent darkening to the bolt under the surface. I did fire off the zinc first before trying to apply the ebonizing solution. Just torching the bolts long enough darkened them alot. The last day in the dip helped a bit too.

Thanks guys


----------



## bsingin64 (Apr 30, 2010)

These bolts will get sat on. I'm hoping an oxide would not rub off like a paint could.


----------



## wood247 (Oct 25, 2009)

Eastwood company makes a kit for doing just what you are looking for. Here is a link. Hope this helps.

http://www.eastwood.com/metal-blackening-kit-with-diamond-clear.html


----------



## bluestone (May 8, 2010)

Novacan Black Patina for lead and solder. Available at stained glass suppliers. Works well on zinc.


----------

