FIRING - a full answer + questions

[Metalman]

From Joysan
"I am brand new to all of this and have to confess a little bit intimidated by it all!!
I intend to order books/videos to help me, but could you please explain what kind of "torch" you are talking about, and where it can be purchased.  Will it adequetly take the place of a kiln until I'm able to get one?!?  I will be starting out with smaller pieces, I'm sure.
Told you I was brand new!!  And confused!! "
Metalman
The torch I use is a small butane unit sometimes called a 'Broule' torch. You can usually find on at the hardware store or a good kitchen supply.  Any sort of torch will work,  it is a question of delicate heat control. That being said, some of the lampworking torches may be too hot.

[Metalman]

Before firing make sure your Art Clay Silver project is completely dried.  You can use a dehydrator for this or just leave it out for a bit until it is dry. The time on this will vary dependent on your work methods and your local humidity. Your piece must be completely dry, if it is not you will have significant problems when you fire it.

TORCH – I use a small butane filled hand held torch, very portable, reasonably priced and easy to transport to workshops and demos. FIRING You start heating your piece(s) with the torch. Shortly after you start, at around 450°F or so, the organic binders will smoke and flame off. At this point I back off with the torch and let this happen.  Now you can take the piece up to firing temperature, you judge this by the middle red color of the piece – if you get too hot, the piece will melt into a blob. One indicator of getting too hot is if the surface starts to look wet or liquid shiny – time to back off a bit with the torch. You can torch fire up to about 25 gms of Art Clay Silver.  25 grams makes a pretty good size piece. If you have Cubic Zirconium stones, they can be fired directly into the clay with the torch. [ take it a little cautious on the heating up stones.] If you get some fine silver bezel wire, you can make bezels and fire them right into the clay.  If you use ACS 650 you can use sterling silver wire and fittings. TORCHESThere are a lot of torches out there but the heat or temperature of your piece is based on your control of the torch --- sooooo....  If you are careful and have a good balanced control of your torch, you can use many  of the other torches.  The important feature for a torch to use for firing Art Clay is to have a large enough flame cone to bath your piece in the heat.  A really small flame tip that is very hot will be hard to use and get the entire piece up to an even controlled heat.

STOVETOP – You will need a stainless steel net or screen and a small cover cage. [DO NOT use aluminum with ART CLAY] Place the Stainless screen on your stovetop gas burner and let it heat up.  You will see red hot areas; remember where these are and let it cool down. Place your pieces on the hot spots, cover with the cage, and turn it up again.  Let this fire for 5 minutes or so, after it stops smoking and begins to glow [that's the organic bindier burning off]. Time is dependent on the size/thickness of the piece.  Let it cool for about 20 minutes, then proceed with your cleaning and finish work. Also, with some of the  "newfangled" gas stoves, the grate is too high for the clay to ever come to an orange glow without removing the grate and putting the stainless mesh directly on the burner.

BarBQue – Using a gas fired BarBeQue is basically the same as stovetop firing
 
KILN - The kiln we are referring to here would be a programmable computer-controlled kiln, basically designed to fire metal clay products. There are several on the open market at this time. ACS fires at 1472F for 30 minutes; 1560F for 20 minutes or 1600F for 10 minutes. This holds for all ACS products except for ACS 650.  650 fires at 1200F for 30 minutes.  If you are firing other metal clay products, make sure to read the manufacturer’s instructions – they are all different.

Note: You will need to kiln fire pieces that use cork clay armatures, large or thick pieces, large pieces of organic material and/or most stones and glass inclusions.

Regarding stones: If you have natural stones, you can test fire them in a kiln [1472F - 30 min] - this puts them at risk, but if they survive, you can build them right into a piece and fire them in.
Your First Torch Firing
So you have your torch and you are ready to get started firing some pieces but you never did it before.  This little test firing or experiment will help you out. First make up two small beads of Art Clay. Make sure they are dry, then set up your firing supplies. You will fire both pieces together for the 1 1/2 minutes.  Now - take one of the 2 items you just fired and push it aside with your tweezers and start heating the remaining one up again. Go  slow but just keep heating.  You want to completely melt this one, but do it slowly so you can observe all of the stages[color/heat effects] and effects of the piece melting.  This will give you a good idea of what to watch for when a piece is melting so that you don't over fire and melt one of your good pieces.

Last note: There are a lot of experimental things to be done. These are new materials. I will tell you all I can but some of the time you are going to go into the experimentiverse.

[Metalman]

Below will be collected firing questions and answers

Metalfairy  A classmate wants to use a MAPP/oxygen gas mis to torch her metal clay.  I told her it is to hot to use. Is that right?  

Metalman     That would be a fairly hot torch but if you are torch firing, the temperature of your piece is based on your control of the torch --- sooooo....  If you are careful and have good balanced control of your torch, you should be okay.  The main feature for a torch to use for firing Art Clay is to have a large enough flame cone to bath your piece in the heat.  A really small flame tip that is very hot will be hard to use and get the entire piece up to an even controlled heat.

Deana  I can not hold the torch for very long or long enought to completely fire a project.  I know that the top of my gas range/BBQ can be used.  What I need help with is the firing times. Can item bigger/thicker than items normally torched, be stove top fired?  Does time differ thicker to thinner?  Hope this makes sense.

Metalman  In general thicker and/or larger pieces need to fire longer - the upper limit here is around 25 grams of material.  If your pieces are larger than this, I would recommend kiln firing.  Another factor will be that the gas range/BBQ may not get as hot as your torch. Because of this, if your pieces are smaller, don't automatically assume that you can fire them for a shorter time.  You probably can do them for a shorter time, but you will need to experiment to find the temperature balance.

Another method here might be to rig up a holster for your torch which aims the torch at your fire brick surface. You could use a vise or a third hand to develop the saddle/holster setup. Then you would set up your pieces; light your torch; settle it in to the 'saddle'; fire and turn it off.

[lexs_creations]

Quote (Metalman @ June 18 2003,2:26)

KILN - The kiln we are referring to here would be a programmable computer-controlled kiln, basically designed to fire metal clay products. There are several on the open market at this time. ACS fires at 1472F for 30 minutes; 1560F for 20 minutes or 1600F for 10 minutes. This holds for all ACS products except for ACS 650.  650 fires at 1200F for 30 minutes.  If you are firing other metal clay products, make sure to read the manufacturer’s instructions – they are all different.

Does this mean that I can't just use a regular kiln like potters use?  (I know nothing about kilns to begin with, so...different kinds?  I had no idea.)  Because in that case I'd have to buy my own, as opposed to sharing one at a public facility, which would be much more feasible for me.

[Metalman]

Basically -YES
If you have an accuratet temperature read out - you could 'babysit' firings but you have to watch out with standard ceramic kilns because the tolerances are wider then you will want for  Art Clay. Check with the manufacturer regarding the temperature range on their pyrometers

[adeptmagic]

I just finished firing a piece of ACS 650.  It was about 8 cards thick, so not thick, but not terribly thin, either.  During the polishing, it broke, and the break inside is white, as if it hadn't been fired.  I fired it at 1200 for 35 minutes.  Is the whiteness and easy breaking indicative that the object is not completely fired?

Thanks!

--Laura

[Metalman]

Laura/Adeptmagic,
I regularily fire ACS 650 at 1200°F for 30 minutes with good and completely fired results. You can fire it at higher temperatures when you fire as long as you don't have any other reason to fire at 1200°. This higher firing works fine and you can run it a bit faster in terms of time. The Art Clay is that silver white color so when you say that the inside of the piece looked that way when it broke does not surprise me. Without handling the piece it is hard to say about the state of the firing.  If you use one of your dental tools or a scalpel, you could scrap at your piece - if you scrapping makes small shiny curls or flakes or shines up the piece, I would say that the firing was complete. If the scrappings are dull and powdery, than the firing was not complete.  The '8 card' thickness should be good although I have noticed that flat designs are frequently delicate if there are deep lines or impressions [like from a rubber stamp] that go all the way across the piece.  2 other thoughts are: I have occasionally kneadded and folded my art clay incompletely and left a crease or unconnected line though the piece - it will come apart there.  Also - I work with both the regular ACS clay and the 650 ACS clay, I could see getting my materials mixed up and trying to fire regular clay at 650 temperatures.
The good news is that the Oil Paste ACS works great for this type of repair. Use a small amount and make sure its dry before you fire. If you have not done any finish work, you can also try a thin layer of ACS 650 overlay paste to start the join and then fill with a bit of clay or syringe material and refire.
Hope this helps.

[adeptmagic]

Thanks, I didn't know that about the curling bits vs the powdery bits...I will check it out!  I have been having some trouble with my kiln, so underfiring is a possibility, but since, as you point out, I can't "overfire" it, I may try longer/higher combos in the future for safety.

[Metalman]

We didn't talk about kilns - I use a Paragon SC-2  THe temp range on these is tight as far as I can tell.  Some kilns have a wide range because the temperature control is not as critical.  Galss and Metal Clay kilns probably have the most specific temp control.  Ceramic kilns can be a bit looser in their range.  Hope this helps.

[ardenb]

'> I am just getting started and don't have a kiln. I saw a demonstration at an art clay booth where they fired with a 1600 degree torch. They said that you could do this for small pieces. How long do you fire a piece with a torch? and what phases does it go through (appearence) until done?
 

[Russ Nobbs]

We've got some general information about firing in one of the other threads here. Look at This Thread

Kurt may answer this in more detail when he's next on line. In the mean time read thru the other thread and see if there are specific questions you can ask him. One of the best ways to learn how it looks and acts as you torch fire it is to take a class so you have hands-on experience while an instructor looks on and guides you.

[Metalman]

Russ is correct on both accounts.  The hands-on instruction helps because the firing temp. with the torch we describe as a color, hard to pin point in words.
25gms is the outer limit on torch firing size - small pieces,1 to 5 gms, you should fire for about 1 1/2 minutes; mediums, 5 to 15gms for 2 1/2 minutes; large, 15 to 25 gms, for 4 minutes.
The piece needs to come up to a good cherry red glow and hold there for the time. Timing does not start until the heat level has been reached.
Any torch will work - it is a question of temperature control - with a hotter burning torch this control can be more difficult.
If you are just starting, and don't have class access - you may want to make a test piece which you will plan on melting - then fire it taking it up through the color ranges until it starts to get really shiny and liquid. This way you will have a visual sense of the heat ranges. As to timing- longer is better as long as the piece doesn't get too hot.

[mursepees]

can anyone give me some tips on torch firing acs 650 using a propane torch?  I melted some and would like to avoid that in the future ;-)  

I am doing little pieces, charms for my nieces and small rings. I have a little experience silver soldering with a torch, but I think that this stuff melts pretty fast.

~becky

[Metalman]

I am copying this here from the Tips thread, it should help you. You will find other helps and tips at
http://www.rings-things.com/cgi-bin....99;st=0
Just a note: because the clay is fine silver, it melts at around 1761°F; sterling silver melts at 1640°F; and your silver solders range from 1490°F down to 1270°F.

Tip for 7/12/05
So you have your torch and you are ready to get started with firing some pieces but you never did it before.  A small experiment to do would be to make a roll or worm of ACS about an inch or so long.  Cut it in half and dry both pieces.  Then set up your firing supplies and fire both pieces together for the appropriate timing.  If you hate the idea of just using the clay for this, make 2 small matching beads.
Now - take one of the 2 items you just fired and push it aside and start heating the remaining one up again. Go  slow but just keep heating, You want to melt this one, but do it slowly so you can observe all of the stages and effects of the piece melting.  This will give you a good sense of what to watch for so that you don't over fire and melt one of your good pieces.
also check this forum thread on firing in general
http://www.rings-things.com/cgi-bin....8;t=323

[jennroar]

Hi I hope this helps... '>  Well I have encountered that same thing and it is good to see how it does melt but I work in a dimly lit area and if you notice the orange will turn VERY bright and then get redish and then that why you have appied too much heat so just back off from your piece a little and not focus on that area. Also, I have just moved to Portland, OR from Honolulu, HI and was wonder if there are other acs users in this area it seems hard to find someone!
*Jen*