Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Blackening tin
Q. I have some galvanized tin sheets that I want to blacken. Want kind of chemical will work for that application and where would I get it.
Thanks,
Mike Evans- Denver, Colorado
2002
? Hi, Mike. I strongly doubt that you mean actual tin metal, i.e., the chemical element "tin". You probably are using "tin" as slang for steel sheet metal?
The reason it matters is that the element tin reacts very differently to chemicals than the element zinc -- so it is important to know whether this metal is tinplate (tin coated) or galvanized sheet metal (zinc coated). Can you confirm?
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002
Q. Ok, I think you are right. It is galvanized steel. How can I blacken it? If you know, please.
Thanks,
Mike Evans [returning]- Denver, Colorado
2003
A. Hi again, Mike. There is a black patina made for zinc (probably most often used by stained glass crafters). I haven't used it, but my best guess is it should work on galvanized steel sheet metal. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Black for tin
2003A. Black for tin (maybe for tin plate too):
- bismuth nitrate.....5 gm
- nitric acid.........50 ccm
- tartaric acid ⇦ this on eBay or Amazon [affil links] .......80 gm
- water...............1 lit
- Hot immersion(70 °C)!
Black for tin II:
- iron chloride........200 gm
- water................1 lit
- Cold immersion!
- Zagreb,Croatia
Blackening steel already in place
WHAT CHEMICAL CAN I USE TO BLACKEN STEEL? IT IS STRUCTURAL AND ALREADY IN PLACE.
SEAN
- PALM SPRINGS, California
2005
A. If all else fails, there's always black paint, Sean :-)
Most good black coatings, like black zinc plating, black nickel plating, and black chrome plating will prove impractical for work that is already in place. You could apply a cold black oxide (gun bluing), but this requires that the steel be very very clean, and it offers no corrosion resistance--you would have to keep the steel oiled, which is probably impractical.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005
! I found out accidentally that galvanized steel can be rusted by using muriatic acid, I was cleaning my pool filter in my galvanized tub. Afterwards the tub started rusting over the next few weeks.
Tammy Rasmussen- Lakeland, Florida
2005
Yes, Tammy, muriatic acid dissolves the zinc coating almost instantly, leaving you with bare, rusted steel
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 2010
Blackening pewter
Q. Hi how do I blacken lead free pewter? Thanks for your help!
Charisse Papworthspin caster - Mapua, Nelson, New Zealand
April 26, 2010
A. Hi, Charisse. Lead-free pewter is basically tin -- usually 90 to 98 percent tin. As such, Goran Budija's suggestions are probably the answer. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 27, 2010
Oxidizing or discoloring tin fishing sinkers
Q. Hi,
I am looking for a low cost DIY method to oxidize or otherwise discolor bare tin fishing sinkers to a flat finish or dark color or both without painting.
Tips or methods for the layperson appreciated.
Thanks.
fisherman - Santa Rosa, California USA
February 22, 2019
A. Hi Steve. I suspect, but don't know for sure, that commercial patinating solutions for pewter will darken tin. Let us know whether it works.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Your Q, A, or Comment: Can I use Patina Cupric sulphate Solution (normally used on Zinc, I believe) to darken/patina a paint can? Is there another solution I should use to get tin black (does not need to be a consistent solid color)? Looking to make candles from pint paint cans, so will need to withstand heat.
Garet FrostMarketing and Advertising - Wichita, Kansas, USA
December 19, 2019
A. Hi Garet. Most paint cans are made of tin plated steel, not zinc plated steel, so chemistry designed to darken tin will probably be more satisfactory. copper sulphate ⇦ this on eBay or Amazon [affil links] will have some effect, but proprietary products which also include selenious acid will probably work better.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 2020
Blackening process for Persian tray?
Q. Does anyone know what the blackening substance is used on middle eastern (Persian) trays. I need to add some darkening to a large decorative tray where part of the blackening was rubbed off.
Marty Wiskoff- Monterey, California USA
December 22, 2019
January 2020
A. Hi Marty. Google links are telling me that the most common Persian tray material is glass, but I suspect that the tin-plated tray that you are inquiring about is made of brass. There are blackening treatments for tin/pewter (and different blackening treatments for brass if that's what you actually have).
Can you tell us what you know about the tray, and send a photo of it to mooney@finishing.com please? Where the black has worn off is it silver colored or gold colored or copper colored? Many/most patinas and blackening solutions are not like paint that you apply on top of a surface, but involve a chemical reaction between the blackening solution and the particular metal of the surface. It's easier to predict what will work if you know what metal the tray or the surface of the tray is.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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