How to etch aluminum panel labels/designs with a reusable acid mix

This tutorial will show you how to etch your own designs/labels into aluminum panels with a reusable acid mix instead of using electricity(the most common method).

It's a pretty good and cheaper alternative to profesional made panels for your home made synths, stomp boxes, etc. :)

As with any work involving dangerous materials, you'll have to be very careful and take any precautions needed if you are going to try this instructable.

If in doubt, don't do it!, and if you do it anyway and get hurt, don't blame me or this website, you have been warned ;)

WARNNG NOTES:

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Acid can burn holes into your skin, wear some protective clothing, gloves, eye protection and gas mask with the appropriate filter designed for acids before handling it!

When the acid mix reacts with the aluminum it starts to produce acid vapours that of course are dangerous to your nose and lungs so by any means, DON'T breath that!

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If you feel like this is too much for you to handle, you are probably right and is time to stop reading this and look some place else, otherwise let's move on:

Step 1: Materials

List of materials:

-Some aluminum panel/s

-A nice design for the etching

-Laser printer w/ black ink

-Some pnp-blue sheets

-Gloves

-Eye protection glasses

-Protective clothing

-Hydrochloric acid (same thing as as muriatic acid)

-Hydrogen peroxide (same thing as oxygenated water)

-A shallow plastic container to mix the peroxide with the acid (2:1 mix, depending on the peroxide concentration you may need to change the mix, I used 11vol. peroxide)

- Another container with water to rinse the panel.

-***Extremely well vented work area*** try this only if you have access to any open and well vented area, the process creates some probably dangerous, and bad smelling fumes, beware!!!
-running water(avoid any metal tool/surface... metal kitchen sink is a no-no, unless you like to spend some $ on repairs )

Comments

[Alcyon]

Hl=ello,
Does anyone know if you could do the etching with natrium hydroxide (cautic soda) ?

[iTixle]

Yes, if it is dilute.

[fudg]

you could always use asphaltum instead of the pnp-blue sheets. this way you can actually etch a hand drawn image if you wanted to. also, it would be easier to cover up mistakes with asphaltum if the pnp-blue sheets didn't work properly.

[smokehill]

Haven't heard of this stuff for years -- is it still available somewhere? Some time back I was trying to research how some early Marine Corps dogtags had the thumbprint etched on the back. My Dad's was the only one I had ever seen, from 1941. Eventually I found out that the USMC did this by painting asphaltum on the back, pushing the thumb into it, and giving it a quick acid bath. Apparently right after Pearl Harbor they cut out that step in the dogtag process to move men thru quicker, and never went back. I assumed it was some sort of petroleum product but had never run across it before (or since).

[aristide202]

Try the greasy smoke of a candle kept close to the plate, Wax will condensate against the plate surface and I think it may work in protecting metal from acid. But now I say why not try melt candle wax itself .
Anyway for home made asphalt try direcct hot boiling in some tuna can resin from any kind of pine tree. Stop boiling when it turns dark and thicker. A very interesting kind of free home made stuff mentioned in Noa's ark materials and then after.

[smokehill]

I've done a bit more research on the old acid-etched Marine dog tags.  It seems there was another intermediate step I wasn't aware of.

Actually, it was the right index finger (not thumb) that was used,  and it was rolled onto the asphaltum mix on the back of the dog tag, much like any fingerprint is taken.  However, before the tag got the acid bath it was "fixed" by heating it over an open flame, apparently cooking the print into a hardened coating.

Only then was it dipped in a (basically nitric acid) mix to etch the print into the metal. Usually the dip time varied, between 30 - 60 minutes.  The whole process can be Googled up without much difficulty, using "marine acid dog tag" or something similar.  The old Navy instructions are in several places.

[shamanwhitewolf]

A quick Google and I found some here: http://www.dickblick.com/products/asphaltum-liquid/#description I don't know this company, I'm just pointing to one possible source.

Apparently, asphaltum is also referred to as bitumen, though other reading seems to give differing definitions of the two.

I like your idea of using asphaltum (or possibly several other inexpensive paint-on products). You could print and cut out you pattern on regular paper, then use that as your painting guide.

[sineSurfer]

If you aim at more artsy stuff, you could use colored wax too, cover the whole panel with wax, remove the parts you want etched with a needle or something like that. Easy to get( any candle will do) and resists the acid bath fine, but forget about precise drawings :)

[msw100]

Cannot buy Hydrochloric acid in the UK will anything else work ?

[aristide202]

HI MSW
Well, I don't know what kind of acid you can find in UK. If you can't find anythig useful in some paint shop where art productcs are sold I suggest to try vinegar , lemon juice or some kind of cola drink. Cola is acidified with phosphoric acid instead of the usual citric acid . See phosphopric acid content in cleanining products against lime spots in steel sinks . Alluminium is not acid resistant as stainless steel and if you remove all traces of wax, oil or the like by mean of hot water and soap I guess you may reach a better result , Use cotton gloves ore some new paper towel in handling the dry aluminium panel against finger prints that contain some kind of skin grease . Make a test on a clean mirror for that. Test some piece of aluminium foil in cola or vinegar for one night and see what happens to clean metal.
I think of making a negative mask of the figure I want to etch then make a uniform heavy black spot on areas I don't I don't want to etch by mean of smoke o a candle kept close to the plate. .
Dish washing powder (very alcaline) could be interesting subject of experiments. I thik that clean aluminium does not resist to lon contact to theese acids, clean copper sure doesn't. I'll test it out this evening .

[sineSurfer]

Hi, I really don't know about a direct substitute for the Hydrochloric acid, have you tried asking for "muriatic acid" at a hardware store? that's where I get it locally.

Other option would be going with the original pcb etching method (ferric acid) look around here in the website, but ferric acid is too aggressive with aluminum, eats away the alu really fast so is not easy to control and most probably you will end with a faded etch, bot worth trying if you like a dirt/old/used/damaged look hehee.

Or go with electrolysis, see jeff-o comment.

Good luck!

[iTixle]

Sodium hydroxide sold as drano could suffice. It would have to be a dilute solution so it would eat through it like butter, but it would work.

[Imgunabeatu]

Hi,

Thanks for taking the time to put together this tutorial.

I'm looking into acid etching a prop weapon i'm currently making at uni specifically the blade which is made of aliminium.

There's a couple of things I want to clarifty:

Is the black area the etched design?
What kind of tape did you use to protect the rest of the ali?

[sineSurfer]

Hi Imgunabeatu, let's see:


Is the black area the etched design?

In the php sheet, whatever is not covered with toner (black) will be etched

In the panel, I painted with black spray paint the etched parts, without paint the etched aluminum looks dark gray and matte, if you like that look you can skip the paint.

What kind of tape did you use to protect the rest of the ali?

I went with 3M scotch magic tape as it sticks very well but is easy to remove afterwards, maybe packing tape can work too.

Try with a small alu piece before commiting with the blade so you can figure out the acid mix strength and etching times and get a better etching in your blade.

Good luck with the blade and don't forget to post a picture please ;)

[Imgunabeatu]

Hey Sine,

Thanks very much for the reply.

I've just got hold of the materials. Hopefully have a crack at some testers this week.

Will do man. I'll let you know how it goes and get some photos up when I've got it done.

Cheers again man. Been a great help.

[diegoeldeleon]

You can save some money using photo paper in the place of the PNP. but not any brand works. Best paper y have found for this (and for the PCBs too)
is "Apli Everyday" 180 grs/m or "Apli "Best price" 140 grs/m:
http://www.mayfairstationers.co.uk/apli-best-price-glossy-paper-p-12911.html

Some HP papers glossy are also good.

Sometimes if your print have a lot of ink area you'll need to put the panels in warm water during some minutes to remove al the paper.

[siamonsez]

Did you do anything to protect the bare metal after the whole etching process is done?

[sineSurfer]

Hi siamonsez, not really as I like the matte look, but fingerprints show up right away. You can try with clear lacquer spray, or maybe aluminum anodizing, check this link:

http://www.thefintels.com/aer/homealuminumanodizing.htm

[lumpee]

ehmbee,you might try "ring the doorbell,the dog needs the exercise"

[ryukyu]

I commonly do etching on PCBs which has the outcome of useable traces. What is the benefit or etching the metal to paint it? Is it simply to protect the paint itself?

[sineSurfer]

Hi ryukyu, "Is it simply to protect the paint itself?" sort of...

In this case, at least for me the final retro/industrial look matters too, have you seen a really old power tool or elevator? I bet they have lettering made using similar methods.

But yes, it does protect the paint from getting stripped from the panel, but you can do it if you are willing to :)

The point is... unless you have the proper stuff and supplies for screen printing which is how most of modern panel labeling is made nowadays, this is a quick and cheap alternative to create your own lasting labels and designs in anything made of metal.

[josh1324]

Is that for an atari punk console? Because I made one about a year ago, it was my first actual electronic project.

[sineSurfer]

hi josh1234, yes it is, great little project and now in a diy wood case :)

[josh1324]

thats awesome! Lol I have mine in a peoples jewelery case.

[josh1324]

btw, I later changed the shity speaker to just a male audio jack.

[trueblackdragon]

Danger! most aluminum etchants produce hydrogen in copious amounts! so no smoking or open flames please!!!

Remember the Hindenberg folks!

[lazemaple]

I have 3% peroxide which is sold in drug stores and 35% peroxide which I think may be too concentrated? Also, do you add the peroxide to the acid or the acid to the peroxide?

[sineSurfer]

Hi lazemaple: I'd go with 35% peroxide as it should work faster, giving more oxygen to the mix to work with... maybe you want to try with a scrap alu piece first to test the etching speed And you must add acid to the peroxide, never the other way, the explanation: A large amount of heat is released when strong acids are mixed with water. Adding more acid releases more heat. If you add water to acid, you form an extremely concentrated solution of acid initially. So much heat is released that the solution may boil very violently, splashing concentrated acid out of the container! If you add acid to water, the solution that forms is very dilute and the small amount of heat released is not enough to vaporize and spatter it. So Always Add Acid to water, and never the reverse. extracted from here: http://antoine.frostburg.edu/chem/senese/101/safety/faq/always-add-acid.shtml

[exlxaxd]

One thing I don't understand: What's the purpose of printing on regular paper and taping the PNP to it? Can't you just print the design directly to the PNP Blue sheet without the pre-printing and taping? Great instructable, by the way.

[sineSurfer]

 Hi, is just to save on the pnp sheet, so you can see where the final print will be and use only enough pnp for the job,  no point on wasting it,  of course you can print just a small square or marks as a guide  and then stick the pnp to the paper ;)

[airfoil]

would a photocopy machine work the same on pnp paper instead of a laser printer?

[flyingpumpkin]

www.techniks.com/information.htm
According to the PNP website you can use a laser printer or photocopier (as long as it uses dry toner which is most of them).  You cannot use an inkjet.

"An image is printed or photocopied onto this film, using a laser printer or photocopier (dry toner based), and subsequently ironed or pressed onto a cleaned copper clad board. "

 

[sineSurfer]

It should work, just be sure to use a photocopier with high quality setting, you want enough toner on the pnp to make the transfer easier ;)

[dr.Maligno]

hi from spain, did you used peroxide vol.11 or vol.110??
thanks

[sineSurfer]

 hola dr. Maligno!, I used vol. 11 as that's all I can get over here, a friend from Tenerife uses vol. 30 for pcb etching, he gets the pcb's etched in 25 seconds! you may want to try with 30 too :)

I'd do some tests on spare aluminum to see how fast the etching goes, as it can be to agressive and ruin your design.

[dr.Maligno]

after doing some prove expreiments, i did try vol.10,vol25 and 30, but its too slow process. At last, i buy peroxide 110.vol and then the pedal become etched.

[sineSurfer]

 that's weird, but good to know it worked at last, post a picture when your pedal gets finished ;)

[dr.Maligno]

last day i upload some photo but i dont know wath happend and finally not load. sending photo......

[elabz]

Guys, I'm missing the important bit of info: what's a "pnp blue"? Is it a transfer paper of sorts?

[ColorfulNumbers]

That refers to "Press-N-Peel Blue," a product for transferring a resist onto metal. It's used for making circuit boards

It comes in sheets. You print your design onto the Press-N-Peel using a laser printer or copier (but not an inkjet), then transfer your pattern from the Press-N-Peel to the metal using a clothes iron. If you place the metal into acid, any surface not covered by the resist gets etched away, but the protected metal remains.

Details on the manufacturer's website here.