138: Enameling Experiments

Project I made 2 years ago – check out Project 114 to see how well that turned out!  (Spoiler, the end product didn’t quite look like this)

Two years ago, I took an enameling class at Water Street Studios in Batavia, IL.  I used that class for Project 114: Enamel Stencils and explored using  laser cut stencils to design unique enameled copper pendants.   I loved it, bought a bunch of lovely enamel and cool MAP gas torch…and didn’t do a lot with them.  Fast forward two years, and something made me wonder: could I use the laser to fuse enamel powder?  When enameling, you basically melt and adhere glass particles to metal (more info on that process in Project 114).  Is it possible that the laser could get hot enough to fuse glass to metal?  A quick Google search seemed to say no, but I was curious if I couldn’t make something work.

 I set up three trials : 

  1. Fusing enamel powder to a copper piece that already had a layer of enamel on it.
  2. Using Cermark, a product designed to laser mark metals, on copper to impart a design, then top with translucent enamel
  3. Use Cermark on a piece of copper that already has a solid base layer of enamel to impart a design

Start point of the trial, 1,2 and 3, from left to right

Materials used:

Trial 1: Fusing enamel with the laser

A little bit of science for you: Medium Temperature enamels fuse at  1,400°-1,500°F.  And an important part of the fusing process is heating the whole piece, so the enamel can flow.  I had doubts that the laser could get the surface that hot, and a laser beam would not be heating the whole surface evenly.  Perhaps the laser could get hot enough to get the enamel to the “sugar coat” phase – which is the first sage of firing, just starting to melt. The sugar coat stage is brittle (think: rock candy like) and adheres better when there is a base coat of enamel beneath it rather than straight metal.  (This tidbit of wisdom is from Linda Darby in the book The Art of Enameling.) 

Fully stuck on enamel powder (ignore that this is grey – I changed my mind and used black after the photos were taken!)

With that in mind, I fully fused two coats of willow colored enamel onto the test copper first.  Loose enamel flies around if you happen to breathe wrong, so I couldn’t sift it on to the piece and then stick in in the laser with the ventilation system on.  To get it to stick, I first brushed on a thick coat of Klyr Fire and then sifted the black enamel powder on top.  This wet the enamel enough to hold it together.

My theory was that that the laser wouldn’t get hot enough to even fuse it.  In an effort to give it the best possible chance, we set the laser to 100% power, 2 % speed.  This gives the laser beam a little more time to heat up the surface before.  “Engraving” the enamel was a little flashy as it hit the glass particles, but nothing too out of hand.  The design looked great laying flat…but the test to see if anything stuck would come with washing.

Flashes of light from the glass particles in the enamel powder.

Looking good(ish) after the engraving

I expected the powder would just wash away, leaving the fused enamel but no…some places it stuck, getting to the sugar coat stage.  Shockingly, though, other places where the laser hit, it completely removed the 2 coats of willow enamel.  It left perfectly pristine copper.  I couldn’t believe it.  Times like this I wish I had a microscope and could see what happened, but I’m guessing the laser just micro-fractured the glass layer to smithereens.  It would be worth exploring if this enamel removal can be repeated in a more predictable manner, and if speeding up the laser a little bit would keep more of the black intact.

Washing away the fused enamel, you know, like you shouldn’t be able to do easily…

Because I didn’t want to leave the bare copper to tarnish, I did put a layer of transparent enamel over top.  Even through the clear enamel fused, the black “sugar coat” layer did not, not really; perhaps the grains were to sparse to melt together, or perhaps they were burnt somehow.

Post clean up, but prior to finishing it with transparent enamel. See the side by side at the end for the finished piece.

Trial 2: Cermark on Copper, topped with clear enamel

Our CO2 laser can’t mark metal by itself, so we use the Cermark (also branded as Thermark) to help.  We first used Thermark  for Project 23: Personalized Collar Stays.  We purchased a bottle of Cermark paste for our studio after that project, and it’s what we used.  Rather than a spray, it’s a paste to brush on.  Apparently, this stuff only has a shelf life of 6 months (who knew!) so it was a little gloppy looking.  (I learned later it mixes really well with denatured alcohol and it’s much easier to paint with then)

Applying the Cermark.

Cermark contains inks, ceramic heat absorbers and low temp glass frit (frit is crushed glass).  The absorbers keep in the heat to melt the glass which protects and adheres the inks to the surface. (Further nerdy detail here.)   So, it’s a kindred spirit to enamel!  

Washed off Cermark 🙁

We knew the Cermark would mark copper; what we didn’t realize was how hard copper made you work for it.  We fired up the laser at 100% power, 10% speed.  What resulted was a very faint marking that actually came off with a little elbow grease.  So we cleaned it up, reapplied and then set the laser to 100% power, 2% speed.  That did the trick.

From there, it was just a simple matter to topping it with clear enamel.  I was curious if the design would stay laser crisp during the torch firing for the transparent enamel.  The glass frit used in Cermark is a low temperature glass, designed to melt at a much lower temperature than regular glass.  I couldn’t get exact numbers, but I have to assume it would less than the 1,400 degrees needed to fuse medium temp enamel.  

Good, permanent, Cermark marking, pre firing

Cermark blurred after adding a transparent coating.

As you can see from the photo, the lines of the Cermark did get a little blurry, but it’s not terrible.  It added a little haze.  More interesting, I think is that the heavily marked areas turned the transparent enamel reddish.  I only put on one layer of enamel (a second one would even out the enamel coating).  I would be concerned the “haze” would spread and the reddish color get deeper if I tried to torch fire another layer.  But perhaps that’s worth testing another day.

Trial 3: Cermak on  enameled copper

We initially engraved all the Cermark coated pieces at the same time, which was silly because trial 2, on left, was on bare metal and trial 3, middle, was on enamel (basically glass.) The round piece I threw in prepped with the trial 3 method, because I was pretty confident that it would work.

Cermark works on metal, ceramic, and key to this trial, glass.  Fused enamel is basically thin glass.  We ran the laser at 100% power, 10% speed, and it fused the Cermark to the enamel.  It actually worked a little too well – it did cut a little into the enamel, recessing the dark lines.  The finished product looked great, but it was a “sandpapery” feeling.  I took the torch to it, in an attempt to soften the sharp edges of the glass, and perhaps give the Cermark a little shine.  Hopefully this fused any microfractures, if there were any from the lasering.   

That extra piece I threw in came in handy – you can see the black is less shiny than on the piece to the right, which got a finishing fire. The difference is more noticeable by feel.

Things that I might try if/when I do this experiment again: 1) Try it at a faster speed.  It should still work,and maybe it wouldn’t cut into the enamel as much.  2) Use the formula specific for glass. Cermark doesn’t offer this, but Thermark does – in fancy colors, even!   

Wrap up

Finished pieces, looking like a motley crew.

I think that there is a lot of untapped potential for using the laser to create precise designs on enameled work.  I’d like to have an expert take a look at the finished pieces, to help me determine if they are structurally sound.  The third trial – using the Cermark as a surface design over enamel – seems the most promising (especially with the potential of colors!)

One thought on “138: Enameling Experiments

  1. alainb1 says:

    Another informative post, thanks for trying this out.

    I wonder what would happen if you pre-heated the copper before you stuck it in the laser, basically hit it with a torch, dust it with enamel, set it on the bed and run the laser. That way the copper wouldn’t act as much as a heat sink since it was already red hot


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