Wotcha,

I have had a read of lots of other posts regarding this and they are directing me to similar info and posts, so I know I'm being a bit impatient by posting a new post about it - but its my 1st ever post and its an emergency!!

I am proficient with metal clays - the silvers - and have had bronzeclay knocking about for a while but not used it yet. Aanyway, a project at uni needed me to make a master of something I've designed and to do it quite fast. Since I don't yet have good wax working/control I opted to turn to my old familiar, metalclay. But because I'm poor as a church mouse at the moment decided to try the bronze.

I spent hours and hours laboring over my model and getting it perfect - a bit daft considering I have never fired or used this different clay!!lol.

Anyway, after firing its split and ruined to hell. I followed so much guidance and advice over firing, and was meticulous about everything. All the comments to other firing "problems" I did. Yet it still cracked up. It took a beautiful patina and has come out strong and bronze - but split, as if it had a core material causing it to stretch (it didn't)

I wondered if the carbon got into the holes of the piece and acted like a core? but I thought I had to eliminate as much "space" as poss?

I demand perfection and a clean and professional look from most of my pieces (allowing sometimes the process of naturalities) but in the main I don't want them to look homemade, I want them to look fabricated and modelled/structured. So, I ask you - am I not really suited to bronzeclay? should I persist? can it be controlled?

I don't mind the complex firing, but it does make me want it to turn out right 1st time! because its so long!! I was gutted this morning when i saw that I've been set back a whole project!! Panic set in and I blamed the bronze! lol. I'm sorry bronzey, but i did do all that was required, so what gives?

I'm going to have to do this again in silverclay and bear the expense, but I really want to know more about this bronze and how to master it - for future ref.

what a wonderful community we artists share here with each other eh?

questions, answers, comments and product lust!! lol.

thanks to any with guidance and patience to read my rant. (O:

Gia. x

1. Did you prefire the carbon?

2. Was it ABSOLUTLEY dry (it can take forEVER to dry)?

3. Did you use a slow ramp up?

4. Was the piece completely covered in carbon? Was it at least 1/2" from the sides of the sink?

5. If you have many pieces put together with paste/slip, were they completely secure before they went into the carbon?

Yes, you should persist. The first few firings can be ... interesting ... especially if you don't KNOW that your kiln is firing at the right temperatures. Lots of problems seem to be caused by ramping too rapidly (and not completely drying). Make sure you're going slow. Bronz is a great medium, but it IS a new product and still has new product issues.

Hi, Thanks for reply....

I did pre fire the carbon - just to be on the safe side.

It was absolutely dry, as I had bored out the centre of rounded shapes..

I did slow ramp up - I followed instructions to slow ramp pieces thicker than 3cards - I also adjusted my pan and pre tested my kiln for hot spots and temperature accuraccy..

It was completely covered in carbon, but not right to the top of the pan - I covered the 2 1/2" pan with about 1" or so, then laid the pieces on (3 pieces only, quite small) and then covered with about another 1" of carbon.. Followed all instructions I have found online and here to avoid probs..the pan was mostly full - with about 1/2" - 3/4" space btween carbon and lid.

I had joined 4 hollowed out pieces together with slip I made using the various recipies of lavender oil/distilled water..making it as thick as possible and using as little diluent as poss so as not to compromise its structural integrety. But - the fact you have brought this up is interesting because it is on the joins that most of the carnage has happened.. Some splitting has happened on the piece itself - the components, and these areas look like they have split around a core (like I said before, there was no core, but the carbon was filling the spaces - maybe too tight??) it split on the rounded formed pieces where they were thinnest.

I thought the pasted areas were secure as I had done a lot of filing and grinding around those areas to tidy up and they remained firmly intact and dusty!

Its good to hear someone vocalise the kiln and firing problems commonly encountered because I suppose one of my tendencies in creative things is to assume its me, that I'm just rubbish at something!! lol.

Really appreciate your advice and any further suggestions as to how I find the correct temp for my kiln..? I've read that too hot, not good, too cool, not good - too fast not good, too slow, not good! lol.

So how does one find the balance seeing as most kilns vary in thier even distribution of heat and, even, in how hot they actually get and if its being accurately read by the thermocouple!

I've got the weekend to continue this - I am still going to turn to silverclay for my master project, but this bronze just looks too good and has too many wonderful possibilities. It helps me to have some facts and advice and "general concensus" to go on.  (O:

thanx again. Gia. x   

 Tonya Davidson (wholelottawhimsy.com) posted this on her blog. It really helped me:

You are going to want to fire it in a stainless steel container. Stainless steel is a good conducter of heat. There are some that believe that the thinner the stainless the better. Also the more you can pack the charcoal the better. Air pockets are not good, thus you can imagine why you haven't seen any hollow forms being made. ... Layering the firing seems to be an issue. The middle layer doesn't seem to fire as well as it should. So if you can put more containers in a load, in a bigger kiln, that's going to be ideal. Also putting posts underneath the container is helpful. This way the heat can penetrate the container.

[THIS FIRING REALLY HELPED ME] ... Programming your kiln for full speed, as the rate, to 1190/1200F with zero hold time is a recommended first ramp. Then firing 250 per hour, as the rate, to 1490F (kiln brick kiln)/1516F (fiber muffle wall kiln) with 2-3 hour hold ramp, for the second ramp. The recommended temperature is 1550 however Celie Fago found that the metal was getting pock-marked and if she lowered the temp to 1516F, those pock marks were lessened. This firing will take 6 hours. It's just extra insurance to fire the whole thing slower, but probably not necessary.

Now remember that everyone's kiln is different. If your thermocouple is older, then your kiln is firing hotter than it reads. So experimenting with your kiln will also be important. I recommend keeping good notes on firing methods and results. Large kilns have a more difficult time firing. There are more hot spots and cold spots in the kiln. ... Many are looking to upgrade their kiln selections to a X14E or a similar kiln in the Xpress line in order to accomodate the Bronze Clay and still do enameling. These are still front loading kilns, but are kiln brick. They are also larger in their capacity. ... There have also been reports of muffle kilns developing cracks because of these firings. More results from testing will be forthcoming. I thought you'd like to know what kinds of things you might expect.

The entire blog post can be found here:

http://www.tonyadavidson.com/musings_and_mullings/2008/07/bronze-clay.html

I found that making slip for joints it really need to be thick. Very, very little water. I roll 'n thin 5mm sausage, let it lay in a little bit of water (half the depth of the sausage) en then mushing (if there is a word like that) with a small spatula as I go along and use that very thick mushing slip for the joints. Also if you do it in two firings - one without the carbon, then do the repairs there are (there always seems to be some) and then do the proper firing in the carbon, there is almost no repairs then.

Try using the powdered form of Metal Mania Bronze Clay. You mix it as you need it, and there is less oxidation. It is also significantly more supple than the pre-mixed "wet" form. Thickness is still an issue... no more than 3/16th of an inch in thickness should be attempted in each firing. Slow ramping on your temps will add to your success, as well as choice of interior material for support.....  cork clay will burn out in a timely manner, as the piece shrinks, and should not cause the clay to tear before it sinters. You can use something as  simple as a wet, wadded up paper towel or napkin to build a piece around, then build up the features.   If you want thick features to your work, you can make something like a small mask,,,,,  roll out the clay and drape it over a high relief mold or into a low relief mold, and allow to dry. The fire. When cooled, you can add more features, up to 3/16th of an inch thick, attach with slip and dry then fire again, you can re-fire as many times as you like, each time adding thickness up to 3/16th of an inch.     The thickness rule applies only to unfired Bronze Clay. (Or copper)

 We have successfully fired many pieces with cork clay interiors. If you do not make a 3 dimensional hollow object, then make sure to support all areas of your piece with the charcoal. snugging it under all nooks and crannies of the piece, as well as against any protruding portions on the top of the piece.  We made a dragonfly, and had to place it diagonally and sideways in the Stainless Steel pan to get it to fit into our kiln. We were very careful how we placed the charcoal around it, so as to lend support to all areas that could slump or bend. 

The powder form of Bronze and Copper clay is available on ebay and from two of the manufacturer's websites . A google search of glass clay or metal mania metal clay should guide you to the sites. All products are available for international shipment.