brass black

[bartley]

On 3/2/2021 at 2:30 AM, JohnU said:

I have one problem with it. The blackening comes off easily. This is especially a problem for flat shim stock. The blackening comes of in flakes when rubbed.

 

Is there some trick to making it bond to the metal?

 

John

Further to my comments above cleanliness is vital as well.  The surface of brass is often treated with lacquer and even if not there is an oxide layer on the surface.  These areas will not blacken so the surface must be cleaned to remove these layers.  Often what happens is the surface is only partially cleaned.  What happens then is that only the clean areas blacken so the article does not seem black enough and we leave it longer.  Then multiple "flakey" layers build up in the clean areas  and eventually rub off.   In neat blackening agent full blackening should occur in about 10 sec.  In a 1:1 dilution - about 30 sec max.  If it takes longer than this your surface is still contaminated.

 

John

Edited March 10, 2021 by bartley

[JohnU]

Hi John,

 

That's interesting. I have not seem nonuniform formation. But the black is not stuck well. I've been chemically cleaning the brass before treatment. In the case of larger pieces I've been mechanically cleaning as well. After removing from the solution I rinse well in water for a minute or so.

 

That said, I do have the Flaking problem. I've left the brass in the solution for minutes rather than seconds. I'll try removing it sooner and see if that helps.

 

John

[bartley]

John,

 

What is your cleaning method? If you think there is a lacquer coating you need a good acetone wash.  I then use a pickling solution but if you do this you must neutralise the pickling solution with bicarbonate and then wash this off before blackening.

 

John

[JohnU]

The brass is uncoated and I use Vinegar for cleaning. What's in the pickling solution?

[bartley]

2 hours ago, JohnU said:

The brass is uncoated and I use Vinegar for cleaning. What's in the pickling solution?

OK John, pickling solution is chemically sodium metabisulphite. It is used by jewellery  people to clean metal and is sold in The US under the trade name Sparex, See here for some discussion of its use in blackening. It is a really good way of cleaning contaminants from brass but if you use it take care not to overdo it as it actually etches the surface of the brass and prolonged use will destroy minute detail.  I use 10 min at 60 degrees Celsius.

 

John

[JohnU]

Thanks John. I'll be trying several things next time I blacken some brass.

John

[allanyed]

Blacken-It was always my go to blackening chemical.  I finally ran out of it and cannot find it anywhere.  Why did they stop making it?  For brass I tried JAX and IMHO it is not nearly as good.  Pickling and cleaning, burnishing, etc and it still has flaking problems.   I love using  L.O.S. for copper, but does not work on brass.

 

In doing a little research I found Caswell plating and Caswell Antiquing-Metal finishing products with a chart for their various chemicals for steel, stainless steel, copper,  brass, bronze, silver, aluminum and nickel.    Some cross over for brass and copper.  Has anyone in our illustrious group tried it?  https://caswellplating.com/metal_finishing_solutions.html    I cannot find the chemical ingredients for Blacken It in order to compare if they are the same or at least similar to the Caswell products for brass and copper.   I just ordered a bottle of Birchwood Casey to give it a try on brass.  If it is as bad as JAX I will try the Caswell product, especially if a member has tried it and gives it some praise.

 

Allan

[druxey]

I'd certainly like to know the best successor to Blacken-It as well, please!

[kurtvd19]

Blacken-It was made by a married couple - very small business.  They died in a car accident - or so I read back when it happened - and the company died with them.  I imagine the EPA scares off any small business that would dare think of replacing the product.

 

Birchwood Casey Brass Black is my standby.  Make sure the metal is clean, dip the pieces in it either dilute or full strength remove and let it drain off.  Repeat as necessary and then was it off let the parts air dry and then rub gently with an old T-Shirt.  Some black will rub off.  If not black enough repeat the process.

 

I was never happy with Blacken-It and had switched to Brass Black when Blacken-It was still being made.

[bartley]

12 hours ago, allanyed said:

 

 

In doing a little research I found Caswell plating and Caswell Antiquing-Metal finishing products with a chart for their various chemicals for steel, stainless steel, copper,  brass, bronze, silver, aluminum and nickel.    Some cross over for brass and copper.  Has anyone in our illustrious group tried it?  https://caswellplating.com/metal_finishing_solutions.html    I cannot find the chemical ingredients for Blacken It in order to compare if they are the same or at least similar to the Caswell products for brass and copper.   I just ordered a bottle of Birchwood Casey to give it a try on brass.  If it is as bad as JAX I will try the Caswell product, especially if a member has tried it and gives it some praise.

 

Allan

 

Modelers certainly do not need to know much chemistry but for the record I have covered it here.  I have not used the Caswell product but its composition seems similar to Birchwood Casey in that it contains both selenious acid and molybdate and the acid is phosphoric.  The concentration of these products varies but I would recommend diluting then to slow down the reaction.  This seems to delay the build up of the "flakey" material which rubs off.

 

John

 

[Tim Holt]

One observation on Brass Black flaking off I've had.   After a full-strength application and a rinse, I can let it sit for about 24 hours, then just wipe it down with a paper towel, or go over parts with a stiff brush.  That removes the loose stuff and leaves a nice dark almost gray iron look. 
 

I haven't tried it yet, but I imagine for little parts I could put it in a container with some mild abrasive (cornmeal?) and just shake it for a bit to clean them.

Edited June 27, 2021 by Tim Holt

[allanyed]

I know this is a bit off track, but we used to put snails that we would catch in the yard into a bucket of corn meal for two to three days to let them clean themselves up before cooking them.  Can't see why it would not work for brass as well.  😄

Allan

[BANYAN]

I have found that once blackened and rinsed, immediately 'polishing' the parts with a soft cloth/paper towel (to remove the powdery residue) works wonders and I then have no issues with 'scale'.  This leaves that nice iron grey finish Tim refers to.  I have no issues with polishing even very fine parts by simply rolling/rubbing them in the cloth/paper.

 

Allan, I prefer a nice juicy steak - I'll leave the snails for you

 

cheers

 

Pat

[Canute]

I'm with you about steak over snails/escargot/scungilli, Pat.

 

May want to read the labels on your blackening product. Some need dilution, others maybe a warmed solution.

 

[Ian_Grant]

Wondered where in the world can I buy sodium hydrogen sulfate, whatever the heck that is?  Apparently "pHdown" for pools is exactly that, and I have a large container sitting in my garage, unused, since my pool's pH always seems to be low every spring, never high. Awesome!!

[Mr von]

Hi guys I confused, I have the Birchwood Casey Gun Brass Black and acetone or lighter fluid but pickle to prepare for blacking im confused will any acid do. Maybe I will go and ask my chemist as i get on very well with him and he could make me up a solution

[Retired guy]

Hi Mr Von regarding what to use to clean brass before you blacken, look on the back of bottle there it tells you what you can use either, degreaser or denatured alcohol.

 

 

I have had great success with Isopropyl Alcohol 99%, I put some in a small ice cream cup (you can use anything) just enough so that it covers what you are going to blacken.

 

 

I keep the parts in the alcohol for a couple of minutes, then take out and put them on a clean dry paper towel, (I use blue workshop paper towel) dry pieces then I put them on a piece of small hard plastic sheet. Using a cotton bud I dip that into the Casey Brass Black bottle and cover all piece I want to blacken. I leave this for 1 minute in the solution, from there I put them in a cup of water, again I leave around a minute.

Then they go back on the paper towel and I dry them off after this I use clean small cotton buds to polish each piece.

 

Doing it this way I have never had flaking, here are some samples.

 

 

 

Hope this helps.

 

Regards

Richard

 

 

 

[Mr von]

Hi Richard you are a diamond thanks so much. I don't like the look of brass fittings on any boat, in my opinion should be reserved for name plaques on office doors lol. I like the look of USED ships. 

Russ

Edited January 17, 2023 by Mr von
miss read what im responding to

[DelF]

On 1/17/2023 at 5:31 AM, Retired guy said:

I have had great success with Isopropyl Alcohol 99%, I put some in a small ice cream cup

Like you I use Brass Black,  with equal success. The only slight modification I'd make is if you need to blacken a large number of small components such as hooks or eyebolts. If these clump together in the solution the treatment can be patchy. I've found that putting the components and solution in a small container with a tightly fitting lid and shaking vigorously obviates any problem. I used to use the canisters that old film rolls came in, but now I've got some even smaller bottles that my wife used to have for washing contact lenses. I've blackened upwards of 100 small components at a time using this method.

 

Derek

[mtaylor]

The only thing I do different is I add an etching step after alcohol (or acetone) and then let dry.  Next the parts into a tub of vinegar for about a minute or two (this etches the metal and gives it some tooth  The last step is just some distilled water to remove any chems.  Let dry and then blacken..   BTW, rubber gloves after putting the parts in the acetone/alcohol to keep any body oils off the metal.  I wear rubber gloves any time I'm handing any parts by hand.  If using tweers, needle nose pliers... the pointy ends get a 2 minute soak in acetone just in case there's oil, etc. on them.

[Canute]

What's your dilution ratio?  1 to 1, 1 to 2 etchant to distilled water.

 

I use distilled water because our tap water or well water has impurities that can affect the liquid we're diluting.

[mtaylor]

Ken, I don't dilute the vinegar.   

[Canute]

I was asking about the echant, Mark. The vinegar is good right out of the bottle. The liver of sulfur has a very specific formula; the Birchwood-Casey does not.

[tlevine]

Ken, the etchant in this case is the vinegar.  If you are asking about the Birchwood Casey, I use a 25% solution.  I rarely use vinegar.  I prefer to use a warm solution of Sparex (dilution instructions are on the package).  It keeps forever in a glass or ceramic container.  Mine is kept in a tiny crock pot which I turn on low when needed.

[Canute]

Toni, yes I was asking about the Birchwood Casey. I had used a 50/50 mix but the black could be rubbed off. Thank you.

[BANYAN]

Not sure if it was from the same company, but I have previously used pre-blackened hooks, dead-eye straps and scale chain.  The parts arrived very black (matt finish) but with a powdery (sooty) finish. The sooty/powdery finish I think is a result of leaving the objects in the solution too long OR using a too strong solution.  This is probably because they are doing the blackening on a mass production basis or using a very strong solution.  A good buff with paper towel sorted that out mostly, but not fully. 

 

I now blacken all my own stuff (PE and brass parts) using Birchwood Casey (BC) as I find, that after buffing, I end up with a better gunmetal colour and sheen sort of finish.  I have tried Sparex (in a crock pot) also, but it did not work too well for me (probably an issue my end), so I continue with my tried and true method of a scrubing the parts with a 'scratch' brush, wash/soak in acetone, rinse, then dip in a 50/50 or less blackening agent for a while, inspect and repeat as required, rinse then buff.  I have also experimented with Carrs and other blackening agents but always return to BC.  I found a large bottle of the solution for a very good price at a gunsmith/gun shop a long time ago and I have enough to see me out.

 

cheers

 

Pat

[kurtvd19]

Clean & Rough the sheet of PE up with an acidic solution - I use Sparex and then rinse with filtered or distilled water.

[Claire7]

I’m new to this and also annealing. Would you anneal your brass parts before blackening? Maybe annealing would also remove any clear finish.

[allanyed]

4 hours ago, Claire7 said:

Would you anneal your brass parts before blackening?

I THINK the blackening has more to do with the ratio of the copper/zinc content of the brass you are using, not the hardness.

Hopefully someone, somewhere, will find the formula used in the old standby Blacken It so we can make it ourselves if need be.

Allan

[kurtvd19]

I used Blacken It - started using it many years ago.  Used the Birchwood Casey (BC) blackener as a trial after Blacken it disappeared and liked it so much more for brass & copper I never missed Blacken It except for ferrous metals.  There are good blackeners for ferrous metals but I don't use much of them as it's easier to machine brass and then used the BC stuff.