Monday, July 15, 2013

It's All in How You See It

Light affects everything we do. In our personal lives too much or too little can affect our mood, our physical health and of course the way we see. In our metal clay lives it greatly affects the way our work is perceived.

Amusingly, when I Googled 'unpolished
metal clay' this photo appeared in the first 5 images.
Those are my fingers! Forgive the dirty nail.
First and foremost, there's that 'white coating' that appears on freshly fired silver metal clay which needs to be 'brushed off' before the silver surface of the metal is revealed. WRONG! That surface is a natural function of the way the light spectrum is affected by the coarse topography of unpolished silver metal. Notice I said 'metal', not 'metal clay'. The white coloration also appears on cast silver, and sheet/wire sterling silver that has been heated to the point where the fine silver has been brought to the surface (called depletion gilding).

To clarify this phenomenon with metal clay, think of the fired surface as a jagged mountain range. When light strikes the uneven surface it scatters and only reflects the white part of the light spectrum. In order for metal clay to develop the silver color we've grown to love, we need to flatten those microscopic peaks and cliffs. A wire brush will transform a Himalaya-like surface into gently rolling hills, providing a soft 'brushed' silver gleam. When the wire brush is inserted into a motor tool (Foredom or Dremmel), more force is being applied than when using a hand tool, and the surface is flattened even more, making the brushed finish slightly brighter.

To achieve a brilliant silver shine, more polishing is required (tumbling or burnishing) to compress the silvery rolling hills down to a neatly clipped golf tee. Get it? Giant Himalayas to Julie Andrew's musical rolling hills, to a flat, smooth golf tee. Okay. Enough with the geographical references. But you understand my point now, right? We could also think of it as Bart Simpson's spikey hair as opposed to Shaquille O'Neal's bald pate.

Wire Brushed vs. Highly Polished
Next let's talk about that smooth surface we've just developed. Silver has the most reflective surface of all the metals. Which means that when the aforementioned light strikes it, it sends back gobs of silvery goodness back into your eyes. So if there is texture on a highly polished silver surface (which is the best thing about metal clay, right? The ability to easily impress texture into your work?), rays of light are striking every surface and plane and reflecting those surfaces. Which sounds good at first, but what that actually means is that our eyes can't distinguish the details of our textures. Which is why metal clayers generally like to use patina. Patina creates light and dark contrast which accentuates the design we've worked so hard to create. I find that even when I apply a black patina and then polish it all away, there is still enough contrast to highlight my texture.

Wire brushed texture, no patina.
Hard to see the texture isn't it?

As long as we're talking about light and it's properties, let's think about why patina colors change if we apply a sealer of some kind. When light moves through two transparent mediums, say air and sealant, the rays are slowed down and refracted or bent to reflect different colors than we expected. So why do some sealants (like Nikolas Spray) protect and retain the original patina colors? I don't know that much. ;) I just like to believe in magic sometimes. I still think the TV and airplanes are magic too. It's all about the wave. Light waves, air waves, sound waves...




So now that you know more about it, let's stop thinking about the white surface of unfired silver metal clay as something to be 'gotten rid of' and start thinking of it as part of the process.


Posted by Lora Hart

Artistic Advisor

3 comments:

Janet Alexander said...

Thanks Lora! It's a great explanation of what we are seeing!

Lora Hart said...

Glad you thought so Janet. I think the 'white powdery surface' is one of those things that many metal clay users don't really understand. Hope this helps some folk.

CT said...

Very nice! I figure if your fingernails are dirty, you have been doing something fun, like creating!!!