Questions about "Liver of Sulfur"

[rlwhitt]

Hi all, 

 

Just saw the product in the subject mentioned by @allanyed in TJM's Flirt build thread and wanted to know more.  Not wanting to hijack his thread, here we are.  Allan, or anyone else that's used this:  How does it compare in effect with the other blackening solutions like Birchwood Casey's?  Does it tend to rub off like those can?   I see it on Amazon in gel and more solid forms to mix with water.  What sort of consistency are you going for - really liquid like the BC blackener, or more thick?

 

Thanks for any input!

 

[MikeR]

Hi Rick

I purchased a 4 oz.bottle of Liver of Sulphur Extended Life Gel from "The Contenti Company".  I mix 1/4 teaspoon of liver of sulfur with 3 oz of hot water.  After I clean the copper with acetone I dip the piece in the solution or use a paint brush.  It does not rub off very easily.  It works great on copper and not well on brass.

Mike R

[rlwhitt]

17 minutes ago, MikeR said:

Hi Rick

I purchased a 4 oz.bottle of Liver of Sulphur Extended Life Gel from "The Contenti Company".  I mix 1/4 teaspoon of liver of sulfur with 3 oz of hot water.  After I clean the copper with acetone I dip the piece in the solution or use a paint brush.  It does not rub off very easily.  It works great on copper and not well on brass.

Mike R

 

That's good to know as kits use so many brass fittings (thinking about eyebolts and split rings) and PE items, so maybe not the best choice.

[gsdpic]

I also used liver of sulfur gel on the copper I applied to the hull of my America.  See post 77 in the build log in my signature.

 

As I recall, I mixed less than the instructions specified in warm water, hoping to have a bit more control over how dark the copper became.  The consistency was just like water.   The patina did not rub off or flake off....it was very much like an old penny, dark brown not black.  Just like a penny, if you rubbed enough or used some sort of cleaner you could bring back the copper shine but it would take some effort.

 

On my copper, I used a clear acrylic semi-gloss spray over the copper and in the years since then it has not significantly changed color...it maybe is a little darker now than it was.

 

[allanyed]

I agree with the above regarding brass.   The old Blackin It was the best, but BC works very well for me on brass.  I prefer to make most metal parts with copper so I can blacken them in situ instantaneously and avoid having to handle them to get them set in place once blackened.  Ed Tosti goes into the use of LoS in his build logs for those interested.  

Allan 

[druxey]

Be aware of the limited life of liver of sulphur. To be effective, it must be fresh.

[allanyed]

7 hours ago, druxey said:

Be aware of the limited life of liver of sulphur. To be effective, it must be fresh.

I agree.  My bottle is several years old or more and still good to go but it is sealed tight.   But, when pouring a tiny amount into a small working jar and thinned down with water, it works great for a few hours, at most.   If the small working  jar is sealed tight as well it is good for some days, depending on how much it has be diluted with water.  The nice thing is that an artist brush full of the raw LoS and equal amount of water in the small working jar is enough to coat a LOT of pieces.  I also find that it is more forgiving on pieces of copper that are not as thoroughly cleaned as I would when using brass and Birchwood Casey and similar blackening agents. Once the pieces are cleaned, finger oils and such have not caused problems for the LoS on copper.

Allan

[wefalck]

Liver of sulfur (a mixture of different potassium (poly)sulfide) and the commercial blackening agents are two rather different animals chemically.

 

Liver of sulfur forms metal sulfides with the exposed copper (or silver) atoms on the surface of the respective metal. So, it is not something that covers the surface, but a chemical compound intimately attached to the bulk of the metal.

 

Being a sulfide, liver of sulfide solution quickly oxides to sulfate (eventually) and then obviously does not react anymore with the copper.

 

Brass blackening solution typically contain a selenium compound that reacts with the two metals in brass (copper and zink) and forms a solid film on the surface that is chemically bound to it. However, if you let the part for too long in the solution, a rather bulky surface precipitate forms that then scales off quickly. Blackened surfaces must be protected by rubbing them with machine oil (for tools), a drying oil (such as lineseed oil) or varnish.

 

Ziselated surfaces of silver cutlery and other silverware are often enhanced by treating the low parts with liver of sulfur (false 'niello') and these areas stay black in spite of daily washing up. However, modern dishwashing tabs seem to contain oxidising agents and the 'niello' disappears after a few rounds in the dishwasher.

 

[No Idea]

Hi - Now firstly excuse my limited knowledge on this subject as I only used brass blackener for the first time this week.  I blackened 2 brass rings that were soft soldered together at their joint.  I was pleasantly surprised to see that the solder had been blackened somewhat too.  Would liver of sulphur do the same thing?  I was expecting to have to touch the solder up with matt paint but found this unnecessary.  If it does I would like to just have an experiment with some pieces at home to see which gives me the best results.

[wefalck]

No, it wouldn't, as soft solder is an alloy of tin with some other metals, mainly lead in the old days, to reduce and control the melting point. These metals/alloys do not form black sulfides under the chemical conditions of a simple 'liver of sulfur' solution.

[No Idea]

Thanks wefalck that’s very helpful. I have always painted brass before but the blackening process is so much easier and looks so much better too.