FastFire BRONZclay Success!

After feeling a bit "burned" by base metal clays a few months ago, I went ahead and tried a new brand on the recommendation of jewelry artist Evelyn Pelati.  I went with FastFire BRONZclay by Metal Adventure and was happy with the results for a variety of reasons.  Here are a few...

To begin with the obvious, it fires fast.  It takes an hour to ramp and an hour to fire.  It is a one phase fire, so set the kiln and forget it.  I was looking for a base metal clay to use with multiple classes, so I do not always have the luxury of being able to run a multi-phase firing during my teaching schedule.  This allows me to not have to return to run a firing on my own time. 

There is the other obvious of the price, with bronze clays being around 30 cents a gram and silver clays being more than $2 a gram, it is the most economical, especially for introducing it to a large class.

The firing directions are clear and easy, particularly if this is your first attempt at base metal clays.  The descriptions of what you will find out of the kiln and what that means for your firing temperatures are also clear.  I was able to figure out my firing schedule after just two test fires, though I have had to make adjustments based on running a whole class worth of pieces at a time.

I have also been able to successfully fire in a ceramic firing vessel.  Since I am flip-flopping between silver and bronze, depending on the class, I am running multiple firings a day.  When you fire in a steel pan there is a black flake sort of fire scale that needs to be vacuumed from the kiln after your firings.  With a ceramic vessel, there is no evidence of the base metal firing.

Last, the workability of the clay has been great.  It has a silky flexibility that makes it great for draping and forgiving for students just learning to work with it.  When it dries, it is easy to reconstitute and continue working.

These were a couple of quick test pieces where the clay was rolled into scratch foam designs and run through the firing.  The bronze has a warm gold hue and nice weight once fully sintered.  

White Bronze Continued

 For those of you keeping track, this is my fourth test fire with White Bronze.  Those first three trials can be seen in last week's post.  After contacting the manufacturer, I took their specific notes on my previous firing trials and began by elevating the firing vessel even higher.  I increased it's height by adding another set of stilts so that its rim sat just below the top of the kiln.  This was recommended since even in my small counter top kiln the difference in temperature from floor to lid can be 300 degrees.  My next step was to do both phases of the firing with the pieces buried in the coconut carbon, it was stressed that White Bronze MUST be buried even for the binder burn off phase with the lid off the vessel.  Since both phases are being done buried in the carbon in the kiln, there was no need to cool in between, so I took the recommendation of the following schedule:

RA1: Full 

PF1:1000F 

HOLD:2hrs

RA2: Full 

PF2: 1250F 

HOLD:2hrs

RA3: 000

START

The above image on the left shows the char on top of the carbon after the completed firing had cooled.  This time I definitely smelled more of a "campfire" smell from the kiln than the previous firings, so I do believe it got significantly hotter.   On the right you can see the test pieces out of the kiln, they already appeared stronger.  There were no cracks and they handled well, so I had hope that the firing had been successful.  I took some 220grit sandpaper to the test pieces and removed enough fire scale to reveal a metallic interior.  As I had found out last week, the water drop test does not apply to White Bronze and the way to check is to sand with 220 grit to reveal the bronze, without small particles coming off.  I was really excited and gave the pieces a wiggle with my fingers, at which point they each snapped in the middle.  

Grrrrrrrrrr!  

So back to the drawing board.  What I do know is that the carbon burned hotter this time and the binder appeared to successfully burn out.  What I don't know is whether the White Bronze was at its full firing strength.  The other thing I learned last week was that even when fired properly, it is very fragile and should really never be used alone.  It was recommended that it be used in combination with other materials for strength.  If it is used alone and fired successfully, customers need to be warned that it is a very fragile material and does not have the traditional strength expected from metals meaning the introduction of other tools such as hammers or pliers would result in it breaking, as well as if it is dropped on a hard surface.  My question still remains as to whether or not I should be able to break it with my fingers.  I plan to email these results to the manufacturer to see if this really is the brittle level of this material or if I should slowly bump the second phase firing by 10 degrees.   I will keep you posted...