BUFFING AND POLISHING BRASS THE RIGHT WAY

How To Correctly Buff and Polish Brass

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First, let's talk about what brass is. Brass is made up of one-thirds of zinc and two- thirds of copper, making it a metal that has a gold color to it. Since it is made up of two-thirds of copper, brass can turn into a green hue after being exposed to different weather after a period of time. Along with turning a different color than its original state, brass can also darken or become lifeless. After reading this article, I can assure that you will be able to turn the lifeless brass into a shiny and new surface while also maintaining its life for longer. 

The number one thing to do when starting this buffing and polishing process is to make sure you are cleaning the brass efficiently beforehand. Brass can collect dirt, oil, and grime overtime : it is important to remove the debris first in order to get the best possible end results. To clean the brass, you can use a variety of items. If you need something fast, warm water and soap will do. However, there are many products on the market that are made specifically for these jobs. A  metal polish or an  All Purpose Cleaner will be your best friend in these instances due to the fact that they contain certain ingredients and chemicals that soap don't -- which will strip the unwanted debris perfectly. These items will work especially well if the brass you are working on is very old and starting to flake or peel. Make sure to let the cleaner soak into the surface for about a minute before wiping it off with a clean microfiber towel.

After cleaning the surface thoroughly, we can begin to sand the brass. A necessary thing to do before you start sanding is to see how damaged the brass is. You will need a lower grit of sandpaper (more rough) for more damaged pieces in order to strip the tough material. A higher grit of sandpaper is best for brass that is not as damaged and does not need much material to be stripped because higher grits are a lot finer. It is recommended to start with a 320 grit sandpaper if the surface has some damage, and make your way up to an 800 to grit. Also, wet sanding can be very helpful when sanding brass because it maintains a smooth surface and helps keep sanding debris and dust from getting out of hand. It is important to stay away from having a heavy hand while sanding -- it will cause scratches which is not the goal. If the surface you are working on is larger, a power tool can be much more efficient and easier for you in the long run. 

The next thing that will get you a beautiful finish on your brass is buffing. Airway buffing wheels will get the scratches that you couldn't get out in the previous sanding step. Along with the buffing wheel, a buffing compound is going to be needed for this process as well. Buffing compounds will ensure a  nice shine and great finish on the brass. A compound with little abrasives or even no abrasives is best to use to avoid scratching the surface this far into the process.

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A black buffing compound is best for buffing and cutting unwanted scratches or material from the surface due to it being somewhat wet and slightly sticky. After you use the black buffing compound, remove the remaining product that is just sitting on the surface with a microfiber towel. You would then want to go in with a brown tripoli compound with a looser buffing wheel -- such as the yellow or white one -- making sure to wipe it after with a microfiber towel. At this point, your brass will look shiny, however, following up with a green compound will give a mirror-like finish (continue with the yellow or white buffing wheel). 

You may be wondering how to actually use a buffing compound bar. The correct way to use it, is by spinning the airway buffing wheel against it without putting a lot of pressure on it. The reason you do not need a lot of pressure is because as the buffing wheel spins, it will create heat causing the compound bar to transfer onto it. Brass is somewhat easier to buff because you can use different compounds (depending on the outcome you are looking for) to make it new again, whereas other metals require certain compounds. 

Once you get the compound bar product onto the buffing wheel, you can start to actually buff the surface you are working on. At this step, you will want to use light pressure and a downward motion -- remember to switch to a new buffing wheel if you start to use a different compound bar to avoid unnecessary scratches. Once you have finished with the buffing stage and you have wiped the surface with a microfiber towel, it is time to properly protect the brass. 

If the brass you are working on will come in contact with a lot of individuals and their hands, it may be smart to add oil -- such as mineral oil -- to protect its life for longer. A spray lacquer can be used if you are refinishing a previously lacquered brass, which will give it a great shine

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To my eye, because the scratches look like they have a somewhat common orientation, it looks like either you have not completely removed the coarser scratches from some prior rougher grit stage during the progression. Or, sometimes if your polish applicator (cloth, paper towel, whatever) itself is somewhat abrasive, it can introduce new scratches during polishing. Or maybe you used the same polishing applicator/wheel/buff of the coarser grit on the finer grit?

A finishing technique I use is change direction with introduction of every new grit. Example, if you sanded radially with 600#, then switch to longitudinal on 800#, then radially again or completely different offset angle at #. You should only see uniform micro-striations of the finer grit with no underlying striations of the prior coarser grit. Vs. if you always do them in the same direction, then prior deeper scours which haven't been completely removed may be getting masked. This isn't always possible on all objects (especially round things where you are trying to keep dimensional conformance), but something to try & do if possible. Brass has nil porosity unless its a very weird alloy, so you should be able to get it to near mirror. Also some polishes have a wax or agent which is more like a thin gloss coating which enhances shine & tricks the eye a bit. As opposed to abrasive only polish. The wax/additive type makes the finish look better for sure, but the wax typically wears or evaporates over time. But that's a different issue.

I also know that photographing metal makes them look worse than in real life so you probably have a nice finish, just want it better.

I just finished a few pen kits & other Xmas objects myself for the first time. I was lurking on that IAP forum & got some good ideas. But I have discovered I do not like 'the brown stuff' on my metal lathe even with ways wrapped in Saran & vacuum on. So if I ever pursue this as a hobby I'd be on the lookout for something like a Taig or Sherline. A lot of guys use a wood lathes but typically not for mostly metal bodies. I don't really have the room or the desire for a separate lathe.

Lets see some more of your work, I'm interested! Thanks for all the advice, I will try Peter T's method of different directions for different grits and see if I can get a better finish. When I started out, I was making pens out of copper which finishes and polishes beautifully but is a cast-iron bitch to machine. I would have to stop and resharpen bits often, especially when drilling out the interior. Then I started using brass which machines beautifully but is harder to finish, and electroplating it with copper. That is how I will continue, if I can get the fine scratches out. Electroplating doesn't cover up the fine scratches, they show right up in the copper and by then it's too late to get rid of them.

These aren't in any particular order, just various ones that I've made .
This was the first pen I sold, probably should have gotten much better before I started selling them, but a friend overseas saw them on my Facebook and wanted to buy a few. She bought this one for herself and bought another one to give to J.K. Rowling as a birthday present (we all lived in Portugal at the same time), apparently buying presents for billionaires is a difficult thing!


Experimenting with different finishes, this was a thin layer of spray lacquer, but it didn't hold up to daily use. I want to get away from using Cyanoacrylate glue (superglue) which most pen makers use as a finish because a lot of makers develop sensitivities to the chemicals.


This is an electroplated pen, showing how the fine scratches from the brass show through into the copper.


Rejects get adapted into suncatchers and Christmas Tree ornaments.


A copper blank showing the difference between unfinished and on the way to being finished.


My first pen in copper for my wife. I hit it utterly out of the park on my first try and haven't come close to this again. This has a CA Finish which still holds up.


This is J.K. Rowling's pen.
My first two pens with CA finish. I've been using CA as an adhesive for models for +30 years but never considered as a coating system. But after seeing so many examples I just had to try out of morbid curiosity. I think there are better finishes but its the rapid buildup of glue + accelerator. Doing a regular clear coat would take much longer.

I went to polish on Green too soon. The picture looks better than real life. I can still see the rolling hilltops of the glue lines that were not blocked down to the base of valleys. But I kind of messed up the wood diameter which was already proud of the pen body diameter & was getting concerned my CA application was too thin in that area so I stopped. On brown burl I applied more coats & blocked with 600# between coats & that helped. More thickness to work with & a better surface to start sanding. The trouble with pens is if you want to sand in a different direction to the rotation axis (longitudinally), you risk making facets which is even worse. What I find works best is a foam rubber pad backing with the right amount of flex. And as mentioned above, fine grit scuff pads have a nice way of conforming to surfaces.





aluminum model rocker covers with 600# scuff pads/wheel. I actually wanted more of a matte finish, just enough to blend out the prior hand filing/sanding. Some people use the scuff pads wet with water or WD-40 id loading is an issue. I know it works on copper but the issue is almost immediate oxide layer, so there may be some tricks to specific polishes.

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I make pens in a Taig lathe, usually brass either left bright or electroplated copper. My question is about finishing and polishing brass. This is after 4 hours of using progressively finer grits of sandpaper, starting at 320 and ending at 12,000, followed by polishing with dialux yellow and blue. And I still have these fine lines. I want a mirror finish but at some point I wonder, are these lines just in the grain of the brass itself, or can I get rid of them? Any advice would be greatly appreciated!
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I have a LOT of experience polishing brass and other metals to a mirror finish by hand.

4 hours is frikken insane time to bury in trying to get a decent polish! Something is very wrong in your set-up! It's either a wrong choice in methods, or materials. Maybe both.

I would suggest among other items worth pursuing, for your needs, is a MicroMesh Kit. https://www.aircraftspruce.ca/catalog/cspages/micromeshstd.php These are used for polishing aircraft wind screens and making them optically 'near' perfect. I have found that going much past grit is a waste, on most metals, unless you are trying to produce a truly flat, perfect, mirror finish! (hint, use a very flat, solid ( I used a lot of Acrylic sheet offcuts, because I had them), backing block as you sand that mirror face!) Past grit or so, you can get a great, near perfect finish, with a clean, soft cotton cloth or a lint-free towel and some metal polish (look for Solvol Autosol! my recommendation!) Clean carefully with soapy water between grits, and wipe off carefully! Use clean soapy water to lubricate the sandpaper (a couple drops of dish soap in a 500 ml squirt bottle is good!) when sanding.

But you should be able to get a lot closer than you have, using autobody grades of sandpaper (up to - grit usually available) used wet, with a little dish soap in the water, as well as some clean soft cotton cloth and metal polish. Same rules apply! Clean between grits!

Primary effort needs to be put in to removing ALL of the previous grit's marks before moving on, and paying close attention to keep from contaminating higher grit abrasives with lower grit particles! At first, you will likely have to step back in the process to restart it at a lower grit, but if you can pay enough attention to a project to work on it for four hours and still not be happy, I figure you have it in ya to spend 35 or so minutes and pay close attention, and get great results! It's a bit Art, and a Bit Science, but these are my experiences in doing what you are trying to!

FWIW, I would work in the same linear direction through all the grit ranges. I found that I had far fewer artifacts of previous work, showing up on the finished product. I did a LOT of this work, by hand, rather than under power and spinning, which would have been MUCH quicker!

Per your later posts, I would say that your problem is one of cross contamination, rather than of a problem with the metal. Consider whether your polishing papers are embedding particles into the work, that are ruining the later efforts! Suggest light pressures, and LOTS of cleaning between wet passes, of the various grits. I know that I never had any trouble getting to a near optically perfect surface, at far less a grit than you claim to be going to!