Round 4 of Test Firing Bronze Metal Clay

Round 4…

The set-up…
Media: bronze and copper separately and together, both pieces 6 cards thick
Kiln: top loading brick
Firing Container: round fiber firing container, no lid (phase 2)
Charcoal: coconut shell carbon, acid washed
Phase 1 Firing: Shortened Phase 1 was 25 minutes on a camping stove with a lid (see details below)
Phase 2 Firing: full ramp to 1340 external pyrometer reading (kiln setting 1250), hold for 1 hour

So here we are again, bound and determined.

I decided to try phase one with Hadar’s shortened recommendation (aka “Pre-Firing Phase 1”). Hadar does have a video instruction of this on youtube. There is also a blog entry from her site with instructions/description.

One difference I found (which may have more to do with the fiber box I was using instead of a steel container) is that the instructions/video state it takes 3-5 minutes for the carbon to heat up, at which point you will see smoke (from the binder burning off). It took my set-up 15 minutes before the presence of smoke.

But when the smoke was done (another 5-7 minutes), I checked and my pieces were indeed dark, so I figured I had completed phase 1 (and if this works, it’s WAY better than firing up the kiln, having it on for 2-3 hours, then waiting for it to cool before moving on to phase 2).

And if nothing else, I’ve learned how to use a camping stove. :-P

I decided to do my phase 2 hold time for only 1 hour rather than 2. I have two dinky little people of testing material.

I just wanted to mention, the fiber box lid had a fuzzy side and a non-fuzzy side and I had no way of knowing which way was supposed to face in toward the bowl. Hmph! I probably used the thing upside-down and ruined it, but oh well.

This time my two test pieces are one copper in bronze, the other just bronze, both 6 cards thick.

Here’s what Phase 1 looks like in action.



The pieces are supposed to look dark (but not fire-scale dark) when they are done.



So out of the kiln after phase two, I have two pieces that look seriously less damaged than any of my previous test subjects.



Again, after brushing I did some intense sanding (dremel grinding) and the pieces appear fully sintered… but where did my copper go?

According to Hadar’s instructions (and I hope my interpretations are correct), the fact that the copper/bronze piece is domed (started off level) as well as the fact that my copper disappeared means I’m still over-firing. The pitting is my third clue.

Although the instructions state to lower the temp by 10 degrees for each test, I’ve been lowering the temp by A LOT more than that and am still over-firing so I’ll do like The Price is Right until I get it pretty close.

I haven’t had a test piece yet with indications of under-firing (I’ve had pieces like that so I have a basis for comparison), so I’ll keep lowering for now and keep my fingers crossed.

I *am* happy that the new super fast phase one firing seems to be a thumbs up. Yay!

Anyway, that’s it for now. Will do more testing tomorrow or Satruday.

The last of my toys has arrived (ultralite beehive kiln). After this, the only thing I can/should order for awhile is supplies.



This has been making the rounds on the internet.



I don’t know where it came from or what the story is behind it but isn’t it awesome? If anyone knows the backstory, please let me know. I’d love to find out who the original artist is.

Here is the orchid I was talking about on Facebook



I’m a confessed plant-killer, yet this thing survived (as a stick) through winter and began blooming a couple weeks ago. Yay! I hope I can continue to keep it alive.

More Bronze Metal Clay Firing Experiments and Kiln Testings

Second test batch still over-fired. (But I just found something online to possibly explain this… argh!)

At first I thought my copper hadn’t sintered (which REALLY confused me… if one can over-fire and one can under-fire at the same time???), but then I realized my impromptu sintering test was dumb.

As you can see in the “before” photo (the rectangle piece that is copper outside, bronze inside), I decided to apply pressure to that ripped corner (after firing, I mean) and sure enough I managed to break it off. I assumed this meant the copper hadn’t sintered, but then I read back on some of Hadar’s blogs and see that:
1) It is VERY possible to break fully-sintered metal clay pieces by hand or with pliers (jewelry doesn’t need to be indestructible… just healthy enough to serve its purpose as jewelry)
2) Sometimes the inside of fully-sintered pieces still looks powdery

Besides, I took that copper piece and used my grinding tool on it and it was copper all the way through without any patches of powder. So in my book, fully-sintered.

The set-up…
Media: bronze and copper separately and together, all pieces 6 cards thick
Kiln: top loading brick
Firing Container: round fiber firing container, no lid
Charcoal: coconut shell carbon, acid washed
Phase 1 Firing: full ramp to 1000 external pyrometer reading (kiln setting 870), hold for 2 hours (then opened the kiln and removed the bowl to cool)
Phase 2 Firing: full ramp to 1450 external pyrometer reading (kiln setting 1340) (although this is debatable), hold for 2 hours (did not open the kiln directly after firing)

I did notice, however, that my charcoal seems to be retaining its heat for a long time after the kiln is off. I didn’t hear the kiln beep (signaling the end of phase 2), but I went out about 2 hours after it was probably finished and when I lifted the lid saw that the charcoal was still bright (bright!) orange with extreme heat.

I’m suspecting that the over-firing has something to do with switching from a steel container to a fiber container.

And sure enough, I just found this on a website: “The manufacturer of the Fiber Container recommends an alternative firing method of firing without the lid and 25° F cooler than specified for the clay type. Container should be removed from the kiln immediately upon completion of the firing cycle. “

Here are the before firing, after firing and steel brushing photos.



It turns out I can sand the blisters and pitting down on the bronze (which also revealed that it was fully sintered), but that’s not an ideal situation as not all shapes of jewelry lend themselves to vigorous sanding.

I’m also spending a huge amount of time going back over Hadar’s blog… like practically from the beginning, because I have questions that I don’t know the answers to.

When Hadar introduced her Quick Fire bronze and copper clays, it was only a one-phase firing. But in the latest instructions, I see nothing that has a one-phase firing. I’ll continue reading the blog (in chronological order) to see if things changed along the way.

Round 3…

The set-up…
Media: bronze and copper separately and together, all pieces 6 cards thick
Kiln: top loading brick
Firing Container: round fiber firing container, no lid
Charcoal: coconut shell carbon, acid washed
Phase 1 Firing: full ramp to 950 external pyrometer reading (kiln setting 875)*, hold for 2 hours (then opened the kiln and removed the bowl to cool)
Phase 2 Firing: full ramp to 1380 external pyrometer reading (kiln setting 1300), hold for 2 hours (did open the kiln directly after firing)

(* Yesterday, when I fired at 870, I had an external pyrometer reading of 1000. Today, firing at 875 gives me an external pyrometer reading of 950 degrees. I wonder if it’s because the ambient temperature of the day is about 30 degrees cooler.)

I also raised the box about a half inch and put the pieces back to horizontal layout per Hadar’s online instructions.



Still mega pitting (and shrinkage). Still looks like over-firing, right? And yet phase one was at 950 (even accounting for the fiber box would only suggest I fire at 970, so still well below the worry zone). And phase two was 1380 which is way below 1470 (1440 adjusting for the fiber container).

This next photo shows you how I know my pieces ARE being sintered (which is one relief, at least). I’ve sanded down (you can tell how far down because in the bronze circle, I’ve sanded past the pitting!) and everything is still intact. All signs point to proper sintering.



The circle with bronze in the middle and copper around it looks different because I added Baldwin’s patina so you can see the difference more strongly between the copper and the bronze.

I think I’m going to try Hadar’s stove-top method for phase 1. Then I won’t have as many kiln factors to contend with. Kiln will only be for phase 2.

So I picked up a camp stove burner for $9 at K-Mart. May try this later today.

So my latest questions are:

1) How fast (or slowly) do I cool my items after phase 2? Do I open the kiln lid as soon as the holding time is up? I feel like I should because these fiber containers seem to stay hot for so long. But I don’t want to risk the integrity of the pieces.

2) To fire phase 1 on a stove-top, I’m supposed to put a hole in the lid of my fiber box. I can’t see where you can buy replacement lids for these so I’m hesitant to do that. The box is $26. But now I can’t remember what else I’d be using it for, so if I’ll always only be using it for base metal clay and I need a hole in the lid… I guess I’ll put a hole in the lid.

More failed experimenting with base metal clay and my kiln

Did my first bronze/copper kiln test yesterday. For the most part, I followed Hadar’s way of testing (copper pieces, bronze pieces, copper in bronze pieces, bronze in copper pieces).

It was also the first time I used my new fiber firing bowl. I can’t tell you how FABULOUS it is to not have to vacuum out the inside of my kiln after each firing. (That black dust all over the kiln after firing base metal clay isn’t charcoal dust… it’s ash or firescale from the steel firing pan.)

The bad news, however, is that my bronze/copper pieces came out of the kiln seriously mess up.

If I’d known they were going to be that unrecognizable after the firing, I would have taken a photo of the pieces in their green state.

The bronze parts are all pitted, blistered, and misshapen. The copper looks best, but was only fired at 1470 external pyrometer reading (kiln setting 1370) so I’ll have to test them further to see if they’re fully sintered.

Aside from adjusting my kiln temperatures (see below), the only other changed factors were: new charcoal and a different firing bowl.

I placed ½ inch of carbon on the bottom of the firing pan, added my pieces, then covered them with 1½ inches of additional carbon. I did note that about ¾ an inch of the carbon had burned away during the second firing.

It is possible that things stayed hot for longer due to the new firing conditions, but I wouldn’t think maintaining the optimal temp could produce the effects of over-firing so severely.

Here was my set-up…
Media: bronze and copper separately and together, most pieces about 2mm thick
Kiln: top loading brick
Firing Container: round fiber firing container, no lid
Charcoal: coconut shell carbon, acid washed
Phase 1 Firing: full ramp to 1000 external pyrometer reading (kiln setting 870), hold for 1 hour (then opened the kiln and removed the bowl to cool)
Phase 2 Firing: full ramp to 1470 external pyrometer reading (kiln setting 1370), hold for 2 hours (did not open the kiln directly after firing)



The pitting makes me feel like I should place my coin-shaped pieces vertically rather than horizontally next time, but all the bronze pieces still look over-fired regardless.

So then I took one of the all copper pieces and started grinding it down, looking for signs of non-sintering.

The thing was sintered.

Extreme puzzlement.

Directions: copper and bronze both sinter at 1000, copper densifies at 1700 and bronze densifies at 1470.

Some of you know that I already suspected my kiln was running hot, so I recently purchased an external pyrometer (thermometer) and have been testing things out.

At lower temperatures (like 500 F), there is a 200 degree difference. At higher temperatures (like 1470) there is a 125 degree difference. This fluctuates, of course.

I will continue my tests, but if all else fails, I will swap out my kiln’s thermocouple and see if that makes a difference.

Here’s what bums me out (or confuses me, take your pick): The previous piece I fired was at a much hotter temp than yesterday’s test pieces.

It was in a stainless steel container and it was a much larger piece, but still… it was not fully sintered and had to be repaired and refired.

This was before I adjusted for my kiln’s over-firing, so it was being fired at much higher temperatures than my test pieces.

Can thinness/thickness have that much to do with temps? Can steel vs fiber container have that much to do with temps?

Okay, later today I’ll mix up some more text clay and see how it goes in round 2.

Stay tuned…

Ah yes... my previous life

In trying to gather bead-related info from some very old blog posts of mine, I ran across this entry... totally not bead-related, but sure brought back memories.  This was actually pretty close to a typical day in the life (for 12 years)...

Tuesday, 01-03-06

Got up at 4:30 'cause DH was snoring.

Drank coffee in 3-second intervals 'cause one of the cats was having a puke-fest and the game was for me to find it before anyone steps in it.

Had to drag the dog outside for a pee (he's afraid of the rain) but I couldn't find any appropriate shoes so stood out there (in the rain) with white ankle socks and high-heeled dress shoes until the dog "performed".

Remade one of the lunches 'cause while I was outside with the dog one of the cats stole Gabe's lunch sandwich (I'm sure I'll find the remains of that within the week).

Got ready for my "relaxing time" in front of the computer (since I'd gotten up so early, surely I deserved some DOWN time) but instead found ants all over the keyboard and computer desk so spent 20 minutes removing everything from there and wiping it down then explaining to them that rain or no rain, this is MY house not theirs.

But the spray I used on the ants made me sneeze and my sneeze scared the cats and when the cats get scared they jump up in any direction, and apparently one of them wasn't too graceful and in his panic to escape my sneeze he knocked over a box of beads and jewelry.

I had to leave that mess for later 'cause it was getting to be time to get the kids up.

Oh great, they both suddenly REMEMBERED they both have homework due today.

It was agreed that I'd do Monica's typing if she'd do the recycling 'cause I type faster than she does and I could already hear the garbage truck on the next street over.

Then Gabe couldn't get his pen to work, but it HAD to be THAT pen 'cause that's what he started his homework with and he'd get a lower grade if he switched pens in the middle (sometimes I feel I should get confirmation of the stories I hear).

So I showed Gabe how to disassemble the pen and tap it to get the ink going, and then he cried 'cause when he went to re-assemble the pen he couldn't find one of the pieces and admitted he was using his sister's pen when she had specifically forbade him and now she was going to kill him.

Before I could come up with a wise and comforting response, I remembered I'm suppose to feed these kids before school so I alternated the appliances between the one electric socket they all share, reminding Gabe that if he got syrup on my beads ONE MORE TIME we'd have discipline issues to discuss.

Then I realized I'd better not leave the house without eating something myself, so I opened a can of tuna and grabbed a plastic fork.

Dang we were supposed to leave 10 mins ago and NO ONE eats in the new car so I carry my tuna upstairs and eat while combing my hair.

But while I'm in the bathroom I notice that the bottom of the bathtub is black which reminded me what I was supposed to remember last night, which was that I was supposed to clean the tub after it drained after my shower 'cause I dyed my hair but the tub takes 60 minutes to drain and I guess for some BIZARRE reason I got sidetracked last night (can you imagine??? Me, getting sidetracked?) so I'll try to remember to get some bleach on the way home so I can y'know... return the bathtub to it's normal color... sigh...

I continued combing my hair and doing my best to make sure the hairs falling copiously out of my head land closer to the garbage than to my can of tuna...

Somehow we make it into the car with only 3 return trips into the house for things the kids forgot.

I back down the driveway and Gabe says, "Blackie was under our tires."

Luckily, I see that the feral is faster at avoiding being run over than Gabe is at telling me about cats under my car and scooted out of the way; I reminded Gabe to next time tell me BEFORE I back down the driveway.

"You both got your gym clothes?" I ask, but the words were barely out of my mouth before I reprimanded myself for asking. After all, was I willing to go back? No. Then why even ask? Why set myself up for the grief…er, I mean knowledge that my kids were going to get a P.E. cut for not having their gym clothes today. I mean, it's not like they had two weeks to think about what they'd need to take to school with them on January 3rd. Oh wait… that's precisely what it's like. D'oh!

Mon thinks she doesn't have her shorts with her. Crap!

But wait, Gabe has an extra pair in his backpack. "You don't mind if they're dirty, do you?"

Mon responds, "Of course not."

I'm wondering if I get a vote in that.

Halfway to school Gabe does his usual, "Oh shoot!" (The definition for that is: I think I forgot something really important that I'll need today at school.)

He then spends the rest of the 15-minute drive taking EVERYTHING out of his backpack (which seems at this point like the bottomless pit of scribbled-on scraps of paper).

He finds "it"… whatever "it" was… a few seconds after pulling into the school driveway. "Mom, you needed to sign this before winter break," he says while handing me a pen.

He then asks how I can sign my name while staring straight at him.

Kissy kissy and reminders of tonight's schedule.

Now it's just me and my car, heading to the office.

And people wonder why I sometimes LIKE to go to work.

More enameling experiments

This week I experimented with soldering and more torch enameling. Here are my efforts (some are for sale, some aren’t… click a photo to find out which ones are for sale).