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Pickling solution for pre blackening


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What are the guys using for cleaning brass before using Brass black . I read on hear that some people are using Sparex in the US but unable to source this in the UK. Any alternative out there in the UK. I am also confused as to why some people are using sodium bicarb to neutralize the Pickling agent and then Acertone afterwards. The last bit is what confuses me , Why would you then use the acertone after the sodium bicarbonate ? Best regards Dave

Edited by DaveBaxt
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Before I found Sparex 2 I used slightly hot white vinegar and salt (one cup vinegar to one tablespoon of salt) then after pickling,  neutralize with baking soda dissolved in water.  A crock pot works well, but if you go that route, get a small one and do NOT use it for cooking later.  If I touch the part with my fingers afterwards I hit it with acetone.  If I used clean tongs during every step between pickling and blackening , I never used acetone before blackening.

 

Allan

 

 

 

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7 hours ago, DaveBaxt said:

Any alternative out there in the UK.

It is sodium bisulfate  (bisulphate).

Here is a quick link that I found : https://mistralni.co.uk/products/sodium-bisulphate-sodium-hydrogen-sulphate

 

It is seriously acidic, but not so potentially violent as sulfuric acid.   Concentrated sulfuric acid "wants" to combine with water.  Much energy must be used during manufacture to concentrate it.   When it recombines with water, it gives back that energy instantly,  If there is more acid than water, the heat is high enough to flash the water into steam.  Adding water to acid, this will produce a steam explosion and acid will be ejected into the air.  The effect of the acid in skin is not unlike holding a live steam nozzle right on your skin.  It will get your attention.

 

If I read it correctly, given times and exposure to oxygen, a sodium bisulfate solution will become a sulfuric acid solution. 

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This sound like some serious stuff and I am not sure I want to go to such lengths to ensure that I have sufficient blackening on my brass parts. Perhaps after due consideration I will see how I get on with acertone and possibly some wire wool. I am very grateful for your reply which may have saved me from serious injury. I wonder what warning is given on the packaging and which way round to add what to what. Best regards Dave

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Sparex is provided in granular form.  It is mixed with water - no danger unless you splash it all over.  Wear eye protection when working with Sparex - you don't want it near your eyes. 

Heating in a small crock pot is safe - it will not allow the solution to boil  - boiling of Sparex is to be avoided. 

It can be neutralized when old using baking soda then pour it down the drain. 

 

Nothing works as good as Sparex (or the chemical equivalent) so why compromise and use less effective methods of cleaning.

 

I have used it for many years - it solved my issues with blackening and plating operations.  I keep my crock pot in a glass baking dish so any spills are contained.  Have used it w/o incident for more than 10 years.

 

There are operations we do every day in our shops that are more dangerous than using Sparex.  Table saws and silver soldering to name 2.

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I've just used acetone (soak, stir, soak for maybe a total of 10 minutes) , rinse, vinegar (to add the "tooth" for about 10 minutes), rinse, and then blacken the part. I use straight tap water for the rinsing but have added a final rinse in distilled water as my current water supply is pretty hard.

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10 hours ago, kurtvd19 said:

Sparex is provided in granular form.  It is mixed with water - no danger unless you splash it all over.  Wear eye protection when working with Sparex - you don't want it near your eyes. 

Heating in a small crock pot is safe - it will not allow the solution to boil  - boiling of Sparex is to be avoided. 

It can be neutralized when old using baking soda then pour it down the drain. 

 

Nothing works as good as Sparex (or the chemical equivalent) so why compromise and use less effective methods of cleaning.

 

I have used it for many years - it solved my issues with blackening and plating operations.  I keep my crock pot in a glass baking dish so any spills are contained.  Have used it w/o incident for more than 10 years.

 

There are operations we do every day in our shops that are more dangerous than using Sparex.  Table saws and silver soldering to name 2.

Hello and thanks for your reply . It was your earlier post which gave me the Idea of using Sparex .Unfortunately I am unable to source this in the UK and ca only get it from the US which is about 4 x cost for postage. I also noticed that a small pickleing pot is also quite expensive here in the uk so I am looking for an alternative. I would just like to thank every one for helping out on this . Best regards Dave

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9 hours ago, mtaylor said:

I've just used acetone (soak, stir, soak for maybe a total of 10 minutes) , rinse, vinegar (to add the "tooth" for about 10 minutes), rinse, and then blacken the part. I use straight tap water for the rinsing but have added a final rinse in distilled water as my current water supply is pretty hard.

After due consideration of finding a safe/cheaper  alternative here in the uk I think acetone  will be the way to go. Sounds like vinegar might help do the trick so will give this a try too. Once again I thank you for your input. Best regards Dave

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Hi Dave

I found several crock pots (in the US)  for under $US20.   If it lasts 10 years like Kurt's, not a bad investment.    It was funny that in doing the search for a mini crock pot, one of them had a picture of items often purchased together with that crock pot and these were  wooden tongs and a bag of Sparex!!   I found some at the following website in the UK but they are indeed more expensive ~~20-30 pounds.   https://www.argos.co.uk/sd/small-slow-cooker/   

Allan

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4 hours ago, allanyed said:

Hi Dave

I found several crock pots (in the US)  for under $US20.   If it lasts 10 years like Kurt's, not a bad investment.    It was funny that in doing the search for a mini crock pot, one of them had a picture of items often purchased together with that crock pot and these were  wooden tongs and a bag of Sparex!!   I found some at the following website in the UK but they are indeed more expensive ~~20-30 pounds.   https://www.argos.co.uk/sd/small-slow-cooker/   

Allan

Well done Allan you have rescued me once again . Thank you for taking your time to do a search for me. Argos of all places, who would have thought haha. Just a thought but would these pots from argos not be too big for my needs?

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I have had good luck in finding used crock pots of the small size as sold by the jewelers supply houses for $4 or less.  I have a spare one under the bench in case the one I have fails and I passed on the others to fellow area modelers.  I currently have two extras that will be passed on to others once we open back up for face to face meetings.  I can't resist picking them up when I see one.

It is important that one uses copper, wooden or plastic tongs when using Sparex if plating of parts is anticipated.  The Sparex etches plain steel tongs and the material that is etched off the tongs goes into solution and will interfere with plating efforts down the road.

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19 hours ago, DaveBaxt said:

how I get on with acertone

All I do is an acetone bath followed by a distilled water rinse then into the blackening solution back in a final distilled water rinse.  I set up the them all up in a row and move the brass (with tweezers or tongs) from one to the next.

Edited by glbarlow
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On 9/15/2021 at 7:12 PM, DaveBaxt said:

What are the guys using for cleaning brass before using Brass black . I read on hear that some people are using Sparex in the US but unable to source this in the UK. Any alternative out there in the UK. I am also confused as to why some people are using sodium bicarb to neutralize the Pickling agent and then Acertone afterwards. The last bit is what confuses me , Why would you then use the acertone after the sodium bicarbonate ? Best regards Dave

Dave,

 

There is lots of info on this site about this - including stuff from me!.  Search for "blackening revisited" for example.

 

John

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4 hours ago, bartley said:

Dave,

 

There is lots of info on this site about this - including stuff from me!.  Search for "blackening revisited" for example.

 

John

Thank you  for the link john. I think that was the first thread which got me onto this Pickling before blackening idea. Best regards Dave

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1 hour ago, DaveBaxt said:

Thank you  for the link john. I think that was the first thread which got me onto this Pickling before blackening idea. Best regards Dave

 

Dave, 

A couple of extra hints.  The exact procedure you need to use depends on the state of the brass. Some is treated with lacquer and the purpose of the acetone is to remove this. Look at my post here.  On the other hand if the brass has an oxide coating (which it usually does) acetone will not remove it.  In this case you need to use metabusuphite ( Sparex).  So a safe procedure is to do both.  I use acetone first and then metabisulphite. If your brass is clean it should only take about 15 sec to blacken.  If you leave it longer it will develop a flakyness which will rub off.  You can terminate the Sparex cleaning with bicarbonate. Then wash with water.

 

In case you are interested I dealt with the chemistry here

 

John

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18 hours ago, allanyed said:

When you say plain steel do you mean carbon steel or stainless steel?   I would think SS is OK, but maybe you have found that is not the case.

Allan:

I don't really know if SS is OK to use.  All the information I have read in the instructions for plating say not to use metal tongs or baskets because they will be attacked by the Sparex just like the materials being cleaned.  As I had a bunch of plastic tongs from my former darkroom it wasn't a problem using the plastic tongs so I never went against the plating advice.  I even found plastic strainer baskets that work well and were cheap (Walmart) - the larger ones do kitchen duty.

Take care,

Kurt

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Roger:

No reason not to and most of the time I do use it before soldering.  But I always use it after soldering to remove scale and carbon from the torch - when using the torch.  If I plan to do anything other than paint the assembly I always use the Sparex to get it good and clean. 

When painting, cleaning with a good solvent, is often all that is needed. 

I have started to clean up after using a solvent by dipping the part in Isopropyl Alcohol and letting it air dry before any further work.  I happened to smell a part after cleaning in Acetone and there was still a slight smell of the Acetone so I figured the part still had a foreign substance covering it.  I figured if I could smell it there was still a residue.

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22 hours ago, bartley said:

 

Dave, 

A couple of extra hints.  The exact procedure you need to use depends on the state of the brass. Some is treated with lacquer and the purpose of the acetone is to remove this. Look at my post here.  On the other hand if the brass has an oxide coating (which it usually does) acetone will not remove it.  In this case you need to use metabusuphite ( Sparex).  So a safe procedure is to do both.  I use acetone first and then metabisulphite. If your brass is clean it should only take about 15 sec to blacken.  If you leave it longer it will develop a flakyness which will rub off.  You can terminate the Sparex cleaning with bicarbonate. Then wash with water.

 

In case you are interested I dealt with the chemistry here

 

John

Thanks for adding that John which explains a lot and why the Sparex is needed. I think the chemistry is not one of my stronger points but will take a look and see if I can digest some of it. Best regards dave

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12 hours ago, kurtvd19 said:

Roger:

No reason not to and most of the time I do use it before soldering.  But I always use it after soldering to remove scale and carbon from the torch - when using the torch.  If I plan to do anything other than paint the assembly I always use the Sparex to get it good and clean. 

When painting, cleaning with a good solvent, is often all that is needed. 

I have started to clean up after using a solvent by dipping the part in Isopropyl Alcohol and letting it air dry before any further work.  I happened to smell a part after cleaning in Acetone and there was still a slight smell of the Acetone so I figured the part still had a foreign substance covering it.  I figured if I could smell it there was still a residue.

I appreciate that soldering is another subject matter but I am assuming using Sparex before soldering helps to clean up the brass so the solder takes better. AS you have already mentioned it also helps to remove any oxides after using a torch. Am I correct in thinking that the blackening will not take to the solder?

               As I am going to try and do some soldering on my current build and listening to your good self I have decided to go down the Sparex route and have purchaced the equivilent here in the uk ( link provided on this thread) I have also purchaced a 1.8 ltr crockpot which will hopefully be suffiecient for my needs. For the record what is the percentage of mix of this stuff to water and how long does it take to pickle before soldering and blackening? Best regards Dave

Edited by DaveBaxt
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1 hour ago, DaveBaxt said:

For the record what is the percentage of mix of this stuff to water and how long does it take to pickle before soldering and blackening? Best regards Dave

Dave,

 

Use about 1 part metabisulphite (Sparex} to 7 Parts water.  It is not critical,  Add the Sparex to the water.   Mot the other way round as it can be dangerous. Operation at 60 degrees Celsius for about 10 minutes is sufficient. Don't prolong the treatment because it is actually Itching the surface.  If you want to dispose of the Sparex pour it slowly into a bicarbonate (baking soda) solution.  It will fiz so do it slowly.  You can then dispose of it down the drain,  Wear gloves and eye protection throughout. It is not really dangerous chemistry but you don't want any of these things in your eyes and the blackening solution is actually poisonous,

 

Regards,

John

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Blackening will not take on regular solder but will cover if using silver solder or a high silver content solder.  I use Stay Brite for 90% of my work and only use true silver solder for more complex pieces.  Once properly cleaned these solders can be blackened as if they were not there.

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2 hours ago, bartley said:

Dave,

 

Use about 1 part metabisulphite (Sparex} to 7 Parts water.  It is not critical,  Add the Sparex to the water.   Mot the other way round as it can be dangerous. Operation at 60 degrees Celsius for about 10 minutes is sufficient. Don't prolong the treatment because it is actually Itching the surface.  If you want to dispose of the Sparex pour it slowly into a bicarbonate (baking soda) solution.  It will fiz so do it slowly.  You can then dispose of it down the drain,  Wear gloves and eye protection throughout. It is not really dangerous chemistry but you don't want any of these things in your eyes and the blackening solution is actually poisonous,

 

Regards,

John

Got it John. Thank you for clearing that up and make sure I get it right.

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1 hour ago, kurtvd19 said:

Blackening will not take on regular solder but will cover if using silver solder or a high silver content solder.  I use Stay Brite for 90% of my work and only use true silver solder for more complex pieces.  Once properly cleaned these solders can be blackened as if they were not there.

Stay brite looks to be available here in the uk and thinking of trying it in paste form hoping it would be easier to use. Thanks once again for your help. Best regards Dave

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