Tuesday, July 1, 2014

My Method for Image Transfer for Metal Etching (Tutorial with Photos!)


When I set out to learn to work with imagery on metal, I found a wealth of online resources out there - blog posts and articles and tutorials and videos, some of better quality and usefulness than others.  Everyone had their own favored methods, materials and techniques for various things. 
One of the most varied processes was getting an image transferred to metal, to act as a resist to an etching acid, therefor creating a 3-dimensional design on the metal.
This process is used in jewelry making and other metalwork such as knife making and gunsmithing.  It is also used to make circuit boards.
I searched forums, videos and websites relating to all of these industries, and discovered that getting a good image transfer is tricky - hence the many different ways that folks have devised and tried to do it, involving irons and torches and films and different paper types and solvents and whatnot.
I tried them all, and most of them didn't work very well.  It was frustrating - as many who had come before me had mentioned.
But after weeks of research and experimentation and failing and tweaking techniques and figuring out what actually needed to happen and how I might be able to accomplish that, I finally figured out a way that works for me.
I now add myself to this list of generous Do-It-Yourselfers who are willing to share their secrets on the web.  Below is MY method for transferring an image to non-ferrous metal (ie: copper and brass) for etching with ferric chloride.

First Off: this method involves a LASER printer.  Inkjet won’t work.  Laser toner is actually a kind of plastic powder that is melted onto the paper to create the printed image.   
This transfer method involves printing the toner onto paper, then using heat and pressure to transfer the toner to the metal.

The kind of paper matters.  After trying many different suggestions (including expensive films made especially for this process, which didn’t work very well for me) the one that worked best for me was glossy magazine paper.  This kind of paper is coated with a thin layer of clay compound that effects its sheen, absorbancy, etc.  What makes it good for our purposes is that the coating keeps the laser toner from soaking too much into the paper fibers, which allows it to release from the paper and stick to the metal when re-heated.

The cheaper kinds of glossy magazine, catalog or junk mail paper is best because it is thin and dissolves easily, which is also important.  My best results (and the paper used in this tutorial) has been with Westways magazine – the free membership mag from the Auto Club of America.  I’ve used other kinds of magazines and catalogs as well with good results.
Bonus for being a material that most of us get delivered free to our mailbox every day (even though most of us don’t really want most of it!)!

Find a page that’s mostly white with text (it shouldn’t effect the transfer too much, but it’s easier to see what you’re  doing if it’s a mostly white page) and carefully tear the page out at the crease.

Some folks mention some ways to prevent the mag page from getting jammed in the printer, since most of them aren’t the standard copy paper size.  I haven’t had any trouble with running them through my printer just by setting the mag sheet in the paper tray on top of a small stack of regular copy paper. Make sure it's centered and flush against the top edge of the tray.

I lay out my designs on the computer in Illustrator to fit onto the pieces of sheet metal I’m using. 
So if I have a 3” x 6” piece, I’ll make a 3” x 6” rectangle in my print file, and arrange my designs to fit comfortably within that space, leaving room to cut around each separate design and some space around the edges.
Print Sheet layout example
Remember that your images must be in negative - black parts will protect the metal and leave a raised area (the bright metal surface), while the white parts will be exposed to the acid and will be eaten away to form darker recessed areas.

I can usually fit the image prints for 3 pieces of metal on a single mag sheet.  Also – since the mag sheets are smaller than regular copy paper, keep your images near the center of the sheet, so they don’t print off the edge.

A nice, dark and dense print is what you want, so fiddle with your printer settings to get the highest-density printing you can.

Put your mag paper in your printer and print your image on it.  It will come out with your images printed over the text and stuff on the mag page.

 At this point I cut out my rectangles that are the same size as my metal pieces, and snip off a little bit of two opposing corners.  Ill be using these to secure my paper to the metal in a moment.

CLEAN and SCUFF your metal.  I use a combo of a dab of Dawn dishsoap and a dash of Barkeepers Friend (a powdered metal cleanser/polish) and a piece of brown Scotchbrite to scrub and rough up the metal surface.  Make sure you scrub in different directions and get all the edges – transfer problems seem to happen most often around the edges for whatever reason.
Another note - the edges of the sheet metal I get are often very slightly curled where it was cut.  Use a rawhide mallet to hammer out any curled edges - you want your metal as flat as possible to make even contact with the hot skillet. Yes, I use a skillet instead of an iron - and it has saved my sanity!

When you rinse your metal, the water should sheet off, not bead up.  Make sure any powder residue is gone.  Dry with a clean paper towel.  Now it’s time for paper to get intimate with metal!

Here’s my setup:
Scotch Tape, Cotton Balls, Acetone, Scissors, Pliers, Burnisher, Clean flat skillet, Dish of warm water (I nuke mine for 30 seconds just before I start), Clean metal, Mag paper prints with corners snipped.  Also, you’ll need a sink and a stove.

The only special equipment I use for this is a burnisher my husband built for me out of a scrap of aluminum and a piece of Teflon he ordered.  It has a nice long handle, is heat-resistant and has a curved as well as “sharp” edge on it.  I most often use the curved edge, as it rides more smoothly. 
Ugly, but FUNCTIONAL!!!

You can probably use any kind of heat-resistant burnisher, such as the bone burnishers they make for paper folding, or the wooden ones made for sewing, like This One.

Just be sure it has a flat area on it so you have a nice wide, flat surface to smooth with.  A longer handle also helps, as that skillet gets hot!
The first burnisher I used was made of plastic and started to melt and get sticky and tear the paper. Not good.

Take a cotton ball and squirt some acetone on it and wipe down your metal surface until the cotton ball comes away clean.  Once the acetone has dried (in like 1 second!), place your image print FACE DOWN on the metal.  Use the scissors to cut tiny triangles of Scotch tape and stick those in those snipped corners to tape the paper to the metal.  Try to keep the tape pieces small and not overlapping imagery that needs to be transferred, as this can interfere with the burnishing.

Place your skillet over medium-high heat, set your metal piece PAPER SIDE UP in the center.  Let it sit for about 2 minutes.  The heat will start to curl the free corners of the paper.

After a couple of minutes, use your burnisher to start to smooth the paper down against the metal.  Start at the center where there is contact and smooth out to the curled corners, so you don’t get buckles and folds, or shift the paper across the surface.  The tape should keep it somewhat steady, but the heat will melt the adhesive after awhile.  Use a light touch – you don’t want to press hard, just firmly smooth the paper onto the metal.  You can use your pliers to steady the metal, but make sure you aren’t touching an area with toner under it, or you can scratch it.

At first, your corners will probably curl back up, but eventually, the toner will start to melt and get tacky and your paper will start sticking to the metal.  Once this happens, take your pliers and carefully lift a corner and check to see if the toner is transferring to the metal.
Once you see some of the black sticking to the metal, you know you’re in business.  Continue to burnish over the whole surface, making sure to get those edges, for maybe another minute and a half.  There’s no exact timing on this, but be aware that if things get too hot, the toner can melt too much and blur.  I use a gas stove – no idea about timing for electric or induction stoves.  You’ll have to experiment.

Not yet!
THERE it is!
Carefully grip an empty corner (I have to use the handle end of my burnisher to slide the metal toward the edge of the pan to get it to lift enough to get my pliers in there) and lift your metal (be sure you have a firm grip on it – it’s hot!) and take it to the sink.
Hit the BACKSIDE – the bare metal side – with a shot of cold water from the tap.  Then drop your piece into the dish of warm water, paper side up.

You’ll notice that the paper becomes translucent and starts to puff around the images.  Let it sit for a few minutes to soften up and release.  Then grab a loose corner or edge and gently peel back the paper.  Some papers come off in layers.  Westways seems to peel off beautifully, leaving little behind.  If you're using a thicker paper with layers, peel off a layer and let it soak a bit longer, then peel off some more. 
Eventually you’ll get down to some fibers that are stuck to the toner.  Rub with your thumbs to remove the pulpy stuff – under a running tap can help. 
You don’t have to get all of the fibers off.  Some tiny fibers will remain stuck to the toner, and that’s okay.  As long as your bare metal parts are shiny and fiber-free, it shouldn’t interfere with your etching.

When it dries, you’ll see the fibers as a whitish fuzz on the toner.

At this point you can inspect for flaws.  There are almost always flaws, which can often be corrected.  If it’s really bad, just use your cotton balls and acetone to clean off the toner, wash your metal again and start over.  You’ve only lost a sheet of magazine paper and a few minutes of time – which is good, because it may take you a few tries to get that hang of this. There are a lot of little things that can go wrong to mess it up - but the metal won't get ruined and you can always try again!

Corrections can be made with a Sharpie marker, acrylic paints, or special stuff they make for etch resists.  I like black acrylic paint because I can use a fine brush and correct even intricate parts of a design that have been marred. 
The consistency of acrylics can leave brushstrokes, which can result in an uneven coverage, so I usually do one coat, let it dry and do a second coat to make sure it’s covered.
Another thing I’ve noticed with acrylics is that if I do an etch longer than an hour and a half, the paint begins to dissolve, which can result in shallow patches of etching where you don't want it.  Most of the time it’s shallow enough that it can be sanded out, but be aware that the paint is not quite as durable in the acid bath as the toner is.

For areas where there is toner and there shouldn't be, I use a needle-point tool to gently scratch away the offending bits.

I correct any flaws in the toner coverage that show bare metal, and I also go over any areas where the layer of fibers hasn’t stuck.  These are areas where the toner hasn’t melted quite as much as the rest of it and there’s just a smear of toner on the metal.  I like to reinforce these thin areas with paint as well.
If you’re fixing an edge that’s going to be cut, you can err a bit beyond your cutting line as you’re going to be trimming and finishing those edges anyway.

Once your corrections are dry, cover the back of your metal sheet with some packing tape and you’re ready to etch!

Here's another example, and a quick review:
Oh - a quick note here - if you're doing more than one piece of metal, let the skillet cool between them.  Starting with a hot skillet can cause overheating and melting and blurring and burning and metal discoloration.
So:
Laser print on magazine paper, clean and scuff metal, swipe with acetone, tape paper image-side down onto metal with tape in snipped corners.  Place on cold skillet, heat for 2 minutes over medium-high heat. Edges will curl.
 
Burnish until toner gets sticky, burnish some more. 
Check a corner. If toner is sticking to metal, burnish for another minute-minute and a half.
Hit the backside with cold water (not shown here) and drop it into warm water to soak.
 Peel and rub loose paper off.
As you can see in this example there are some major flaws in this transfer.  I managed to salvage the two earring designs at lower left, cut them out of the sheet, and cleaned the toner off the rest of the metal, which I can use later.

I hope this tutorial is helpful to other self-educators and makers out there!  I want to give special thanks to my husband Dore for taking pictures of this for me, as timing is critical once you get going!  And for making me a custom burnisher that works perfectly. He's the BEST!!!

I also want thank all the bloggers and artisans and YouTubers out there in InternetLand who have shared their knowledge, with special mention for Nancy Hamilton, who has a bunch of videos on YouTube on jewelry making; tools, materials, equipment and projects.  I kind of love her.  :)  Check out her videos here:
In The Studio with Nancy Hamilton

That's all for now!

1 comment:

  1. Thank you! Love the tutorial and your work!

    ReplyDelete

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