Etching on Any Surface Cheaply and Without the Use of Chemicals

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Introduction: Etching on Any Surface Cheaply and Without the Use of Chemicals

About: I'm the kind of person who's mind doesn't stop. Literally, I take medication to fix that just so I can sleep at night. I have an unhealthy obsession with making things and believe, firmly, in sharing what I ...

This is another of my proprietary processes that, up until now, I've pretty much kept to myself. I've used the Paasche air eraser for many years, and with most people using chemicals, I've turned it into a bit of a small business. I'll add a bit of an overview video at the end of this instructable so you can see the process.

**Due to interest, and folks mentioning that they're having trouble finding these tools, I've created another instructable on how to fabricate one at home. I did try and keep it as simple as possible and resource friendly for those that don't have a well stocked workshop. You can find it here;
https://www.instructables.com/id/Making-A-70-Glass-Etching-Tool-For-Less-Than-10-Co/


One of the biggest advantages to using the air eraser, over chemicals is the variety of materials you can etch on. With chemical etch, you are pretty much limited to glass, and even then, it's difficult, if not impossible to create anything decent on tempered glass. I've successfully etched on glass, plastic, brass, chrome etc. Basically anything with a gloss surface will take an etch. Now, there's also the issue of pollution, waste and many other issues that arise from using chemical etch. Suffice it to say, with the air eraser, there's far less cleanup, and far less impact on the environment.

Secondly, is the cost. Sure, the initial expense of buying the eraser and compressor can be a bit much, however, once you realize that your etching compound can be sifted and recycled over and over again, you're looking at next to zero overhead, other than purchasing masking material (which can be acquired from the dollar store) and the power to run your equipment.

Now this process is far different than sand blasting that uses silica. The air eraser uses a fine aluminum oxide powder that leaves a very shallow, almost untextured etch. Whereas sand blasting can leave a rough porous finish, and can even weaken the glass, the air eraser etch is smooth, very clear and doesn't create small crannies where dirt can build up and ruin your work.

An obligatory caveat:  The etching compound is not terribly good for your health, and although it doesn't leave any chemical film behind on your work, it should not be breathed in. It is aluminum after all.  I highly recommend you build an etching box, (which I may make an instructable for later on), or at the very least, wear a mask and goggles while you work. A big advantage of having a box is containing the powder for reclamation and sifting later on so it actually works in your favor to play safe.

Step 1: Tools and Equipment

Tools:
Paasche Air Eraser - can be purchased most places that sell airbrush equipment
Silent compressor - If you can't find or afford one, check out my other instructable on how to make one
Etching box -  Great way to reclaim your compound, and keep your work area dust free
Ladies Nylons - The powder is very fine and will pass easily through a double layer of nylon material and leave dirt behind when filtered.

Equipment:
Frisket/Masking material - Spend $10 a roll at the art store, or grab clear shelf liner from the dollar store. They're exactly the same.
Aluminum Oxide Compound - There are different grades but fast cutting works fine.

Step 2: Making Your Stencil

Any stencil will work, provided you can fit if over your project. An advantage of using the air eraser is that the stencil doesn't have to fit perfectly because the flow is in one direction, so if it is lifted on one part, you don't have to worry about overspray. And since it's not a liquid, you don't have to worry about it bleeding underneath.

I find that I prefer custom stencils, and for that, you'll need a printer. Ink jet works the best, but you can use a laser like I demo in the vid. You just need to attach a sheet of paper to the plastic side to prevent it melting against the roller. You can make your own stencil from scratch, if you have the photoshop skills, however, a quick search online will usually turn up exactly what you're looking for.

An important thing to remember: You'll be printing on the paper side of the stencil, not the plastic, so you'll need to invert the image before printing, otherwise it'll end up backwards. Another point is to leave small bars connecting 'islands' in the stencil. They can be removed later, when the stencil is attached to it's surface. This will make it easier to keep things nice and lined up.

Step 3: Setting Your Stencil

Having a nice secure place to set your work is crucial. What I'm using is some old packing cardboard to hold my glasses in place, but you can make your own custom jig.
Now, when you're working with curved surfaces, you'll find it easier to set your stencils by hand. You can lift and reset anything that doesn't stick down properly, but you can expect to have bubbles and wrinkles. That's alright. Remember, the powder doesn't bleed, so as long as you don't spray at an angle, it shouldn't get underneath. If you're working on a smooth, flat surfact, you can add a transfer layer to your mask. This is done, simply, by putting a layer of masking tape over the top of the frisket to ensure that it goes down nice and evenly. Once it's in place, you remove the tape leaving the frisket stuck to your surface.

Step 4: Setting Your Air Eraser/Compressor

Compressor:
Having the right pressure on your compressor is crucial. I've found the optimum operating pressure is between 45 and 50 psi. Setting it higher could damage your eraser. I like to double regulate my pressure, setting the first at around 60psi, then setting a second regulator, with moisture collector at 45psi. This gives a nice even flow, while preventing moisture from getting into your tool, and gumming up the lot. There is also a second moisture trap on the line that comes with the air eraser. You should definitely use this line as even the smallest amount of water can cause some serious annoyances.

Air Eraser:
Setting your air eraser can be a bit trickier and is more of a personal thing. The finger trigger is threaded to allow restriction of air flow while there is a second screw on the bowl to limit the flow of compound. For my own use, and because I reclaim over 99% of the powder, I set both to maximum flow. Unless I'm working on finer detail like shading or highlights, there's no need to limit the tool.

Nozzle Clogs:
It doesn't happen often, but it does happen. Usually due to moisture, or pieces of dirt that have mysteriously found their way into your bottle of compound. Keep a needle nearby to help clear out any small clogs. It'll keep you from having to disassemble the tip every time. For bigger clogs, you will have to take it apart, so keep your micro wrench handy.

Step 5: Creating Your Etch

There's really no trick here other than to take your time and make sure you get everything. Now it's a good idea to mask off areas all around the etch. I can't count the number of times I've forgotten to take my finger off the trigger when pulling away from the piece, and almost ruined it with over spray. Suffice it to say, plan ahead.
The etch will only go so deep, so you don't have to worry about overspraying any one area. Keep the nozzle about 3-4 inches away, (unless you're shading where distance is better) and fill in every area. A nice bright daylight bulb, in your box will go a long way to showing areas you may have missed. Just make sure your light source is sealed because the compound is conductive and you don't want to start a fire with it.

Step 6: Cleaning Up

Once you've finished spraying, you can remove your masking and wash up. Simple soap and water will do the trick. There's no special care requirements, other than don't put them in the dishwasher if you don't want them to get ruined or worn.

For the powder you've used, I've found that if you take a pair of ladies nylons and double them up around a mesh strainer, you can clean and reclaim as much as 99%. This means a low overhead cost, but more importantly, less environmental impact than you'd get from the use of chemicals.

Step 7: Finishing Up

That's all there is to it. Here's a short video on my process so you can see how it's done.

I hope you enjoyed the instructable. Thanks for following.


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62 Discussions

0
user
RuthQ1

3 days ago

i'm just starting to set one of these up using a plastic tub as the cabinet type set up. do you need to have a vacuum system operating to keep the air clear with the eraser or just an air filter would do??

0
user
LizG36

9 months ago

How do you adjust the air flow on the air eraser? You state "The finger trigger is threaded to allow restriction of air flow" but I don't know what that means in terms of actually adjusting the air flow. I'd like to increase the air flow on mine and just can't figure out how. Great instructable by the way :-)

1 reply

Overall the air is controlled by the regulator on your compressor, which shouldn't be set higher than 60psi. However, you can set your comp to max (60psi), and adjust down via the trigger. It simply adjusts the 'stop point' when the trigger is depressed, kind of like a governor on a car engine. The screw on the cap of the reservoir limits flow of powder, as well as air flow which can also be adjusted. Wide open, it'll empty the reservoir in seconds, while restricted, you'll get a longer spray time, but the etching will be much slower.

What size air compressor is needed to do this?

The air eraser only surface etches, and isn't as abrasive as a sand or bead blaster. It may work if there's a polish on the stone but I doubt it'd be very visible. Best to use rotary tool etching on stone.

Okay, thank you for the info. I was a little skeptical that it would do the job.

0
user
KimN29

2 years ago

The hopper is way too small on the air eraser. I bought a blast cabinet but the gun a nozzles that came with it seem way too big for the fine aluminum oxide. I can't seem to find a product a step up from the air eraser that doesn't have the tiny hopper problem.

1 reply

The big mistake many people make is to open the flow up 100%, which will drain the reservoir in seconds. I do a small class and teach the etching as part of it. When I instruct people, I generally recommend choking it down to between 25-40% max. That ends up being roughly 1-2 minutes of straight spraying.

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user
gluvit

4 years ago

Awsome

love the doctor who glasses! I'd make some but I don't have any kind of etching tools :/ good instructible though!

1 reply

I created an instructable on how to build a simple etching tool, if you're interested. You can find a link, to it, in the intro. It was designed to be as simple as possible since I, literally, built it in my kitchen, in under an hour, from parts I had laying around in my junk drawer. If you can't find aluminum oxide, I've tried a few alternative powders for etching with, as per suggestions in the comments, and found that baking soda, icing sugar and corn starch all seemed to work pretty well. Hope that helps.

Nicely Done.

My wife uses the same aluminum oxide in her sandblasting...

You version is a scaled-down version... I like the use of the eraser for this function... why use the big blasting cabinet for a smaller job right? But I also wanted to point out that you can use the photo-resist to get more detailed artwork... you just need the UV developer, or you could use sunlight.

2 replies

Really interesting take on the masking process with the photo resist. If I understand her process correctly it's kind of like using one art image to create another art image then destroying the first to leave a high quality finish. Big cost in time, I think, but definitely worth it.

Glass blowers call it "white lung" which not that dissembler to black lung that afflicts coal miners. The lesson is ventilate ventilate ventilate!

Hey, I found it! In basment I bought one at a yard sale! for ten buck. but I didn't know what it was. I thought it was an airbrush.

They can be pretty hard to find since they aren't a common, or popular tool for most. If you need compound or parts, check with airbrush suppliers.