Enamel Cross Project (part 4)

Enamel Cross Project (part 4)

This is the fourth part of my enamel cross project, for the previous part see here.

I've just finished the lower section of the cross, here's how it looks now (above):

 

I'm so pleased I didn't mess this stage up! I took plenty of photos along the way, so see below if you'd like to read on.

Starting the bottom section I'd engraved in the previous part I, first, cleaned and degreased it. Then I added some washed opaque powdered enamel to the differnent sections of the piece by wet laying. I started with the blue (Milton Bridge Lapis Blue O128)

applying enamel to the bottom section of the enamel cross

 

first coat of blue enamel applied

The blue's all done, now apply the red around the border

red border enamel applied

Now the flower, I need to have a mix of white, red and pink for the petals so I've started here with the white to build up the sections. The background for the flower is opaque black.

rose flower colour applied

The six fluer-de-lis and it's ready for it's first firing - all the surface area in the recesses is covered with enamel.

fluer de lis colour applied

Here's how it looks after the first firing, and cooled for a bit. The exposed gilding metal has oxidised in the kiln and will need to be cleaned.

after the first firing

The piece is pickled in a hot bath of sulphric acid and, in this case, cleaned with an abrasive to reveal the yellow gilding metal. I used the abrasive to bring back the metal colour so I could select the enamel colours appropriately as I go. With some firings I won't use the abrasive as it's not necessary once I know what colours I'm using. So here's how it looks at this stage:

after the second firing

I did a check to see if the piece still fits with the next section, it does! So far so good!

check if it still fits

Here's after the next layer of enamel

bottom section next layer of enamel

Fired and check again, still OK!

check if it still fits again!

Grind back again as I still need to see the colour of the metal to get the overall feeling for the colour scheme. I set the piece into to plastic-wax to protect the edges from getting a radius during this procedure.

bottom section grinding flat

After a few more firings this is how it looks after it comes out kiln and then out of the acid bath. Pretty manky! Ughh. The red is probably copper oxide. The sulphuric acid takes a long time to disolve the red copper oxides. The black copper oxides are dissolved pretty quickly. It should look fine once it's all ground back again - errr hopefully anyhow!

bottom section after a few more layers of enamel

Before grinding back, however, I noticed the piece was bowing. I was surprised since I'm using 4mm thick gilding metal so I thought this would be enough to resist the forces the enamel exerts. However I had engraved quite a lot of metal off the top so reducing the thickness. Anyway, whatever the reason, I counter enamelled the back of the piece to try and balance the forces. For this I use my pot of random bits of enamel powder which, at the moment, comes out in battleship grey:

bottom section counter enamel

Back to cleaning up the piece

grinding back and preserving the edges

This is cleaned up enough to see the design, I haven't completely ground the metal back to yellow as you can see some of the gilding metal is red. This, I believe, is due to a reduction gilding of the metal. The zinc in the metal is more volatile than the copper and so escapes from the surface of the metal during firing. This leaves a layer of copper on the surface of the gilding metal. I may be quite wrong mind you!

All the enamel, built up in the recesses, are nearly flush with the surface of the metal so almost there.

bottom section showing matt enamel

Here's after the final firing. Before firing I'd made sure all the enamel is flush with the surface and ground back to clean up all the enamel-metal interfaces.

bottom section last firing

I set the piece into plastic-wax again and polished with wet pumice on a slow felt wheel. This gives the metal a satin finish.

bottom section after pumice polish

I also polished a bit more with jeweler's rouge. I could do more here but I think it's adequate for now, when all the pieces are done I'll need to polish them all at the same time to make them all coincide with each other. The gilding metal tarnishes over time and the whole finished piece needs to be consistent.

bottom section after polishing with jeweller's rouge

After cleaning off the excess rouge I come to this, my first finished piece!

the finished bottom section

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