Can brass be etched with vinegar?

I have heard of people using vinegar but would expect it to be pretty slow. I would use a mag wheel cleaner which works much faster. Eagle One Etching Mag Wheel Cleaner will work in a minute or two. Spray it on, rinse it off thoroughly. Also make sure these don't have a clear coat on them. 

When shopping for wheel cleaners make sure it mentions etching for rough cast aluminum. Cleaners for polished aluminum won't etch the surface for obvious reasons.

Pete

Saw this on the internet
Title Is: Best PCB Etchant in Every Kitchen . It is for copper and brass has copper int it so it should work.
I etched a lot of brass with a commercial PCB etching solution using dry transfers and scotch tape for masking and it always turned out great."You may want to try a piece of scrap brash to see how long it takes for your desired result that you are looking for.

Never tried this method but the reviews look good and it is probably the stuff that you already have a home, low cost and safer.

Copy and past the address below:

http://www.instructables.com/i...t-in-every-kitchen-/

PCB board etchant is ferric chloride. (edit, I see the bottle is indeed labeled Ferric Chloride).  It will work and is very fast. Not sure how the price compares with etching wheel cleaner though.

Might be worth it if you plan to do a lot of work with brass as I know you have Ron. I use it to remove excess solder on brass engines. Apply with a Q tip and it will remove solder  (tinned not blobs) faster than it etches the brass. 

I have a gallon of the stuff from the days when we made our own PC boards. It lasts forever so no worries about shelf life.

Pete

Pete/Ron,

Thanks for your input.  I have a bottle of PCB etchant so I'll give that a try tonight.  

Dave

Try with scrap brass first and let us know how it works out, be careful.

Are your brass hinges coated to prevent tarnishing?
If so, I wonder whether an etching solution would remove the coating.

C W Burfle posted:

Are your brass hinges coated to prevent tarnishing?
If so, I wonder whether an etching solution would remove the coating.

Great observation CW, I did not think of that.

CW is correct, maybe soak them in lacquer thinner/paint remover first and hit them with steal wool of scotch bright to remove any clear coat.

Milwaukee Road Dave posted:

Anyone have experiencing using vinegar on brass?  If so, is there a time limit on how long to expose the brass to the vinegar, i.e., overnight versus a limited number of hours?

Yes.  Several hours will not cause a problem on good heavy brass - vinegar is only about 8% acetic acid.  Use distilled white vinegar.  I routinely use 30-50% acetic acid on brass cars - 15-20 min.

Key issue is completely rinsing // neutralizing the acid before doing anything else and then totally drying.

Would not use ferric chloride for this purpose w/o some means to immediately quench and rinse completely clean and clear to remove the acid component - no idea of the actual quality of the hinges, but I'd think you'd like to have them survive the experience.

It appears only one of us has actually used ferric chloride on brass models. I usually just apply to specific areas using a Q tip. Its not like dropping it into a pure acid. You will have time to work without getting close to causing damage. For these hinges you can immerse them in the liquid. Assuming any clear coating is off, give them a minute, then wash thoroughly in clear water for a minute. It will be obvious if it has had an effect. The brass will have a pinkish hue. You can remove the oxide with a steel wire brush on a dremel.

These have been cleaned with ferric chloride.

You would have to immerse them for several hours in heated ferric chloride to dissolve them. 

Pete

I used distilled vinegar on some brass car sides for an old Walthers kit.  It worked just fine.  They paint has adhered well over the last 6 years I've had it painted.  I can't say the same for the car sides adhering though.  Need better glue to keep them in place.

Has anyone tried  liquid ammonia to clean brass ??  I know they don't like each other.

And tarnished brass....what would one use to remove tarnish from a brass model?  I understand that one has to remove the clear coat first.

I have two metal polishes on hand. Flitz and Simichrome.
I tend to use the Simichrome because its been easier for me to find, and it works wonders.
Novus polishes for plastics.

Steam Guy posted:

And tarnished brass....what would one use to remove tarnish from a brass model?  I understand that one has to remove the clear coat first.

There are products available at your local hardware store made specifically for this. Flitz is one brand. This is a liquid spray. They also make a paste polish but probably not the easiest to use around fine details. 

As for ammonia I'll leave that to the chemists.

Pete

Steam Guy posted:

And tarnished brass....what would one use to remove tarnish from a brass model?  I understand that one has to remove the clear coat first.

Brasso is what the military uses. It is available at Walmart and is very easy to use.

Steam Guy posted:

And tarnished brass....what would one use to remove tarnish from a brass model?  I understand that one has to remove the clear coat first.

The 30-50% acetic acid that I use takes care of that in about 15 min.  I also used to use hydrochloric acid (~25% conc) when I had a large cleaning bath available.  The ferric chloride solution is usually a nitric acid solution - it'll work but (1) after having nitric acid burns I tend to avoid it and (2) the acetic or hydrochloric are both single component solutions and less complications are something I prefer. 

Whatever you use, just make sure that you fully clean and neutralize, and then dry the surface prior to painting, and do that as soon as possible since that fresh clean surface is already ready to react with everything in the air.  I used to zip lock items under nitrogen or argon.....

What is the method for neutralizing?  Is it just wash well and dry or some other chemical application.

Thanks,

Ed

Thanks to all for your advice, unfortunately I got side-tracked last night and couldn't try some of the suggestions.  FWIW, the hinges are H-style doll house hinges sold under the Mayberry Street Miniatures brand.  I got them from Hobby Lobby and were selected because they have sufficient friction between the hinge barrels and pin.  I am using these to hinge drop-down bay 'gates' for a 17 bay/2-sided icing platform.  The design is based off of pictures in the Church, Thompson and Jones PFE book.  I believe the prototype was in Roseville, CA.  For my purposes I want the gates to be functional, therefore I needed them to stay in the up position without any other mechanical assistance.  Other H-style hinges I tried (another Hobby Lobby brand and some from Micro Mark) had little to no barrel/pin friction and would not stay in the up position.

I do not know if they are clear coated, but in my prototype trials when I tried adding tooth with sand paper there was a noticeable color change in the brass, so they may very well be coated.

From the various suggestions, I clearly need to be careful because I do not want the etching process to negatively affect the existing barrel/pin friction.

I will attempt using etchant with a Q-Tip followed by a good rinsing with water.  There are 64 hinges I need to prep before painting so I would prefer a faster etching process.  I have used etchant before with aluminum so I know that it is very aggressive, and if you do not rinse thoroughly will keep working even after removal from the etchant solution and subsequent rinsing if not well rinsed.

Thanks to all again, I will report back after I do some experimenting.

Dave

Milwaukee Road Dave posted:

 

I will attempt using etchant with a Q-Tip followed by a good rinsing with water.  There are 64 hinges I need to prep before painting so I would prefer a faster etching process.  I have used etchant before with aluminum so I know that it is very aggressive, and if you do not rinse thoroughly will keep working even after removal from the etchant solution and subsequent rinsing if not well rinsed.

Thanks to all again, I will report back after I do some experimenting.

Dave

Well, you could make this fast if you were sure any clear coat had been removed. You mentioned you had some ferric chloride. Place a drop on the hinge and see if you see a reaction. It should start to discolor the brass in a few seconds. If not then it has a clear coat. 

If I had 64 of these I would find a metal strainer basket and do them all at once. Since I have access to virtually all of the chemicals mentioned so far I would probably opt for the dilute acetic acid but I doubt you could find that at your local hardware store. Second choice would be the white vinegar. Dip them all in a container of liquid, let them sit for a while depending on concentration, and then rinse them off. If you happen to have an ultrasonic cleaner run them in a dish soap and water mix.  Then dry off with compressed air.

If I only had a few I would use the ferric chloride but that would involve a few more steps to rinse, then remove the oxidation. 

Pete

Ed Walsh posted:

What is the method for neutralizing?  Is it just wash well and dry or some other chemical application.

Thanks,

Ed

I will use 1 of 2 possibilities:

(1) is to use a cold water rinse cycle of the dishwasher and air dry.

(2) is to rinse (immerse) in methanol 3-4 x's, 1-2 x's in acetone, compressed "air" dry and then get primer on asap.

So  I did some experimenting last night.  Took a fresh out of the pack hinge and applied PCB etchant to the surface, which immediately beaded up.  Obviously a clear coat was in play so I rinsed and dried the hinge and then scuffed all surfaces, this time using a jeweler's flat file.  Perhaps not the best choice but a bit easier to manage than sand paper.  Re-applied the etchant and it dispersed better, but not great.  Let it set for about 45 seconds, no noticeable bubbling but I got twitchy and immediately rinsed and dried the part.  About 50% of the surfaces had etched, a good thing, BUT....there was a noticeable change in the friction between the barrels and the pin.  Not good.  I need this friction to stay intact, so I scraped the notion of etching.

However, I did find an attachment in my dremel kit, a conical bit with a very fine point, and tried using that in the dremel tool to scuff the surface.  It works fairly well not only in getting the clear coat off but also scuffing the surface.  It will take some time to do all 64 hinges, but that's ok.  A bit of patience, some good music and a good beer and I'll be able to knock this out in a reasonable time.  Besides, the whole project is a test of patience.

For those interested in what it is I am actually doing, here is a picture of the prototype gate.  The model will require 32 of these.  The other picture shows the platform at the end of the assembly stage (finishing the addition of cross braces).

Thanks for all the help.  It is greatly appreciated.

Dave

Something to consider. Paint, clear coat actually makes a good primer. Why not skip the prep and just wash them in soap and water and paint?

Pete

Pete,

Good question!  I was avoiding mentioning this because I know it is wrong, but I will be using an acrylic paint on the brass.  Plenty of modeler's rationalizations for why, but primarily because of the color.  Using hinges was not my preferred design option in the beginning because I 'thought' they would appear too large, didn't even pull one out to see.  But after many failed attempts at alternate designs, I figured what the heck, let's try a hinge.  And to my surprise it didn't appear all that large.  But I thought that if I could match the color of the hinge to the stained wood that the size would appear smaller still.  Looked at maybe a half dozen different colors of steel and settled on the Model Master acrylic steel color.  The best color by far for my purposes.  So, using an acrylic with brass means additional headaches.  I picked up my order of paint last night before running the etching experiments and my LHS guy suggested putting down a coat of lacquer primer first as it should adhere to the brass fairly well, and then put the acrylic paint coat on top of that. 

Thoughts?

Dave

That should work just fine. Try it on one and let it sit a couple of days to get an idea how durable it is. Rub it between your fingers.

FWIW I never use primer unless there are pits and have been painting brass and diecast since the '60s. Model Railroad paint is pretty durable. Craft store acrylics I can't vouch for.

Pete

Pete, 

Thanks for the input, that's what I intend to do.  The acrylic is model paint and seems as durable as any other I have used.  The flaking issue I am experiencing is due to my moving the hinges up and down.  I hope that with a bit better adherence to the brass I can overcome the flaking.  Worst case is that when all is assembled and in use, I have to go back and touch up with a brush, not a big deal.

Thanks again.

Dave