April 30, 2011

The Strange Joys of Etching Brass

(Updated 08-15-11)
Hey everybody,

I wanted to share what I've learned recently while working with brass on my latest build for the "Transphonic Regulator". Rest assured this walk thru is a mess. Pretty much like me.

Starting into this I knew very little about etching metal besides doing home brew circuit boards. I researched a ton of different options weighing the pros and cons. In the end I settled on the toner transfer method combined with acid etching.

It's a fairly straight forward process, but it does take a little practice to get good quality results like the picture above.

To begin you'll need to figure out what your going to etch. I started small so it was easier to work with and I wouldn't be too upset if I screwed it up.

What you see in my hand is a solid brass corner protector for hobby projects. I bought this in a pack of four at my local mega hardware store. What I really liked was the fact that they are solid brass and not aluminum with a fake polished brass finish.

(Important: The quality of brass is very important. It is not easy to figure that out from just looking or handling it. This etching process can bring out the beast in poor quality brass, in the form of "red rot" or dezincification. Once it starts on a piece you're working on you might as well toss it. Because there isn't any stopping it. I got extremely lucky with the brass corners used in this walk thru. None of the ones I have etched have any red rot. But in using a solid brass kick plate for some larger pieces, every single piece from this plate has come down with it. So depending on the quality of the brass this process can become expensive. I suggest you run tests on a small sample of the brass you intend to use. It could save you a lot of heartache in the long run.)

(Point of Interest. This process will also etch other metals such as aluminum, steel, and copper. But know if you get aluminum with a brass finish the etching process will eat through the fake brass finish and expose the silvery aluminum color beneath. Which may or may not be desirable.)

Now I take measurements of the corner piece so I can design the art to etch into it. I had to take into account the fact that the corner protectors have a smooth edge on them instead of a sharp edge where they bend around. So I had to design my art away from the edges. More on this later.

I fired up The Gimp and layed out my design. I stuck to a simple black and white 2 color design, as any form of gray or half tone is undesirable. Your art is going to end up being a mask to protect the metal. Anything that's white will wind up getting etched and anything that's black will be protected. If any part ends up being anything other than white or black it wont transfer properly. So don't even attempt it. A feature I love that The Gimp has is setting the images "Print Size". This can let you print your image to very exact dimensions. So once you've got your art go ahead and do a test printing on standard paper using a laser printer. DO NOT use an inkjet printer as the "Toner" transfer method requires "Toner" to work properly. The toner that is used in laser printers contains plastics. These plastics are what will protect the metal from being etched in certain parts. Inkjet inks do not contain these plastics and will not work with this process.

I tried to fit as many copies of my design as I could on a single sheet of standard 8 1/2 x 11 paper. Waste not want not. Now go ahead and cut out one of your designs and do a test fitting on your metal piece. My design does kinda look like a triangle but it's actually meant to be a square with one corner blank so I can handle it and tape it down later. If you're satisfied with the result then it's time for the real thing.

For the real thing you're going to need some Press & Peel Blue. I have tried many other types of paper others online have mentioned as well as some they haven't and for the money  vs. quality Press & Peel Blue was worth it in my opinion. It's a little pricey but it's also so much easier to use.

Anyway go ahead and print your design on the P&P. Do not print your design on the shiny side of the P&P, print on the paper like side. Like I said before I tried to fit as many copies of my design as I could on a single sheet mainly because the P&P is expensive enough I don't want to waste any of it, and I know I'm going to mess up because I was learning.

Now cut your designs out (a few at a time if you want) try not to touch any of the toner on the P&P because the oil in your skin can be problematic later.

I found a scrap piece of wood to secure my corner piece with thumb tacks so it's a little easier to handle without having to touch the brass. Again the oil from your skin thing.

It is always a good idea at this stage to clean your metal. A lot of real brass is covered in lacquer to protect its shine, but this covering will prevent the etching process. Put some Lacquer Thinner on a rag and give it a good scrubbing where you plan on putting your design. Do this until you're sure the coating is gone. It's not necessary to remove the lacquer from the rest of the metal as it will help protect the rest of the piece from etching. After that give it a good scrub with some standard rubbing alcohol to remove any oils or residue from touching it.

After you've cleaned it sufficiently place your cut out art printed side down to the metal. Line it up to your satisfaction. On my art I left a corner free of toner so I could use some standard cello tape or paper tape (i.e. painters tape which doesn't stretch or warp under heat) to help hold it in place. It's hard to see in the pic but trust me it's there.

Now your gonna need an iron. No not the soldering kind of iron, but the clothing type. When the iron is applied it will melt the toner that is on the P&P and adhere it to the metal.

Use a plain sheet of paper between the iron and your taped down design. Just lay it on top. This will help keep your design from warping, moving, or sticking to the iron.

Using the iron is the real finicky part of this whole ordeal. I originally followed the P&P directions to the letter, but the results were less than perfect. I had bubbles and parts of the design didn't stick so I had to experiment. Now others may disagree with me on these steps, as to how it's done, but as I stated this is the way it worked best for me. Based on trial and error for the size of the corner piece I turned the iron to max heat and without pressing down set the iron on top of everything trying to balance it in the middle for exactly 1 minute. After that 1 minute I held the regular paper firmly down so it wouldn't move (it's important to not let the paper move as it could move the P&P beneath which could cause your design to shift, smear, or just look like butt) and slowly shimmied the iron sideways off to one side for another minute. Your time may vary so experiment. As I stated before I designed the art to be slightly away from the edges because of the curve the corner piece has around its sides. You never want to try and iron the P&P on a curve or bend. The design needs to be on the flattest part of the metal as possible.

(NEW INFO 07-04-11: If you are not getting consistent results due to cold spots in the iron my wife showed me a trick used by seamstresses for clothing. Get an old pillow case and use it between your iron the piece you're ironing. The cloth will help distribute the heat more evenly and allow the iron to glide easier. I obtained more consistent results using this method. I also discovered that using an iron on much larger pieces of brass is exponentially more difficult to achieve a good transfer. In this case I have found that using a thermal laminator is indispensable. As the laminator applies even pressure and heat across the entire piece. The laminator I have started using is an Apache AL13P. It is steel constructed, very sturdy, and very cheap compared to the plastic home units most people will find in stores. I can run a piece through it multiple times until the toner adheres, and get a near perfect transfer every time.)

If all goes well you should now be able to clearly see the design through the shiny plastic back of the P&P. It should have a fairly uniform black color to it. If the black looks splotchy or uneven then you may need to put it back under the iron for a little longer. In the picture above I tried to show side by side the before (lower) and after (upper) ironing look.

At this point your going to need a bowl with some cool clean water. I carefully cut the tape holding the P&P, pulled the thumb tacks, and gently dropped the entire brass piece with P&P into the water. Be carefull as the metal should still be extremely hot.

Let the metal cool for a couple minutes then remove it from the water. Don't shake it or try to dry it yet just gently and slowly pick a corner of the P&P and peel it back. I found that for me keeping the plastic bent and slowly (even painfully so) peeling it down tword the bottom of the piece gave me the best results.

If all goes well you should have something similar to what you see above. A nice smooth black mask on the metal. If something went wrong and your design doesn't look right or your missing chunks of the mask on your work, use some lacqure thinner on a rag to clean the mask off the metal and start again. Don't get discouraged if this happens multiple times, as it takes practice. Just try try again. In the picture above slightly to the right of the bottom center mounting hole, you may notice a small mistake in the mask. This is not necessarily the end of the world. Using the step below you can paint over the imperfection so you don't have to start over. If your happy with the outcome then gently dry it off with a soft rag. Try not to rub as this can remove the mask you just applied.

Now we need to protect the rest of the metal so only our design gets etched and nothing else. I borrowed some of my wifes top coat nail polish, but there are many different things you can use for this. Such as lacquer, acrylic, and sometimes even tape. I chose nail polish because it drys very quickly, and it's a small piece of metal so I won't have to use a lot. I painted all the exposed metal on both sides except for the design. I even painted inside the screw holes. Be thorough and take your time as rushing only leads to mistakes.

Now comes the fun and mildly dangerous part.

First your going to need some Muriatic Acid, which is available at just about anywhere you can get pool supplies, and Hydrogen Peroxide. I also used a small plastic cup for measuring out the chemicals. The cup is actually from a bottle of medicine, but since it has measurement lines on it it turned out to be perfect.

You're also going to need a small tub of water and, since we're using acid, some baking soda. Baking soda is used to neutralize the acid.

And the rest of my ensamble consists of nitrile gloves, plastic dish deep enough to submerge your piece to be etched, plastic or glass sealable container to store etchant after use, plastic syringe or turkey baster, large trash bag or plastic sheeting to protect your work area, and frosty beverage. This procedure is best done either outside or in a garage with plenty of ventilation as the fumes from the acid are dangerous. Seriously don't breath this stuff in it can hurt you.

Now we need to make our chemical etchant. Put on your nitrile gloves. Don't worry I'll wait till your done. Ok, did you put them on and snap them at your wrists like the doctors on TV do? I did. Anyway the etchant consists of 2 parts hydrogen peroxide to 1 part muriatic acid. For me I took my little measuring cup and filled it up twice with hydrogen peroxide first and dumped it into my bowl. Then I dried off the inside of my little cup and added 1 measuring cup of muriatic acid.

(Important Note: always add the peroxide first and the acid second. If you pour the peroxide into the acid it could pop, sizzle, or explode all over you which would not be good. Always pour acid into water, never pour water into acid.)

Now that we have our etchant mixed and in our bowl gently drop the metal on in. At first the mix will be clear but as it starts to work its magic it will turn a light green color. This is normal. The metal that is being etched will slightly change color as well. It should start looking like a lighter matte color. Every couple of minutes I would use my suringe to suck up some of the etchant and gently squirt it onto the design to remove any bubbles or gently swirl it around. If bubbles form on the metal in your design they will stop the etching process. Your mileage will vary as to how long it takes to complete the etching to the depth in the metal you want. The best way to check is to just pull out your metal, swish it around in your container of fresh water and baking soda to neutralize the acid then gently run a finger over it to see if it is deep enough. If not drop it back into your etchant and continue as before. I left these pieces in for about 30 minutes to get a nice etch. When your satisfied it's deep enough swish it around in your fresh water and dry it off.

(Important Note: the chemical etchant we have made is not meant to be disposed of. It can be used over and over again. Store it in a plastic or glass container that can be closed for its next use. You can not use a container with a metal lid as the acid can eat through it. Eventually it may turn a brown color or just start taking forever to etch. If this happens you can add a little more acid and a little more peroxide. Pour it back and forth between the bowl and storage container a few times to give it some much needed oxygen and it should turn a bright green again. Remember the etchant is a dangerous chemical and should be treated as such.)

Now grab your lacquer thinner and scrub off the mask to reveal your hard work. If you want go ahead and use it to also remove the other paint or sealant you used to help protect the rest of the metal. Pretty isn't it? Almost.
If you click on the image to make it bigger you may notice some dark splotches around the design. They are much more noticable in real life and are caused by very minor bleed through of the acid. I had this on almost all the corners I etched. It's fairly easy to take care of though. If this doesn't bother you and your happy with how it came out then skip the next couple steps. If you want to fix it then keep reading.

If you don't have either a dremel or polishing wheel then this part will be much more difficult. One of the two is highly recommended. It also helps to get some polishing compound. The one I got came in a stick form and is meant to create a high gloss shine. I used it in conjunction with a dremel and a felt buffing attachment.

I kicked on my dremel and gently ran the felt buffing wheel up against the polishing compound stick until the wheel had a green tinge (the polishing compound I used is a green color). Then with smooth steady movements I polished the entire visable surface of the corner piece. In the picture above I polished half of the piece so you could see the before and after. It truly gives it a beautiful mirror finish. Don't worry too much about polishing the inner etched surface unless you just want to. I rather prefer the contrasting look of the mirror finish and matte toned etching.

When you're done, wipe down the metal with either a rag or some paper towel to remove any residual polishing compound. Then step back and marvel at your accomplishment. I sure as hell did the first time I completed one I really liked.

Now if your happy with the way everything came out and you don't want to do anything more to your metal then get some lacquer (spray on or paint on) and give the metal a decent coat. This will protect your polish job and keep the brass from tarnishing.

But if you're like me and never satisfied (it's like a curse, right) then you may attempt to fill in the etching with some sort of black paint. With this I can't help you as I am still working on this myself. I still haven't found any decent info on what types of paints or inks are the best etc. etc. All I've found are blanket statments saying "just fill in the etch" which doesn't really help a whole lot. If anybody has any pointers I'd love to hear them.

Anyway, I hope this "clear as mud" guide helps others who are wanting to try something different.

Have fun,
Steve G.

I'm also including some pics below that show some of my early experimenting with different types of paper. Most of the different paper I tried created pitting and massive bleed through. If you are wanting to create an older/used look then this might be what your looking for.

 In the above picture I used a type of paper called Super Solvy. Which is a water soluable paper used mainly for sewing. The paper dissolves almost completely in water in about 10 seconds. The wood fibers that were impregnated in the toner allowed the acid under the mask which created pitting and other strange designs.

 In the picture above I used standard copy paper. Again it caused pitting, and is not easy to remove excess paper after ironing.

The above pic shows the use of glossy paper from a magazine. Many others love this method, but it didn't work good enough in my opinion.

(Disclaimer: This how to guide is from my experiences only. As always your outcome may vary. I can not be held responsible for any damage or injury you may incure from following these instructions. Use at your own risk. The chemicals and procedures used can be classified as dangerous. Please take proper precautions and safety measures when doing any sort of work on your own.)

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