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New To Kiln Firing And Need Help


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#1 Daleen

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Posted 27 July 2013 - 12:25 AM

Morning good friends, its 6 am in South Africa. A few months ago i bought a few moulds and a very old kiln second hand but never got around using it as i was busy opening a craft shop. That was November last year, wow time flies. Anyway, about 3 weeks ago i decided to go out and get started with this. Problem is i seem to be the only one in my area doing it and help is scares. I found some ceramic slip, underglazes, tools etc and casted my first few items, unmoulded, let it dry, cleaned and then tried to fire. Problem is i had no idea how the kiln worked and the cone sitter was non existing, kiln came on red hot after switching on, but i placed my things in the oven and first it sounded like pop corn, i immediately opened the kiln to found some of my new masterpieces were popping and breaking, so i assumed the heat was just too hot and it needed graduate heat adjustment, but with now switches in working condition i propped open the lid and peep holes, let it heat up for an hour, then closed the lid halfway for an hour, then closed completely, then peep holes etc till it was closed and then fired for an hour. All took about 5 hours, its not a big kiln. Let it cool and it came out not bad, but was not white, more than a off white color, so i assume its slightly over fired. But then disaster struck, i heard a pop and the kiln did not want to came on again, looked inside and the elements snapped. Because its so old and tired looking hubby decided its not worth fixing, as i already spend quite a bit of money on tools, underglazes and sit with moulds,i decided to venture out and find another kiln, got -again a second hand one and over 400 used moulds,which i am so happy with - the molds it is, the kiln, i decided i am not going the second hand route again, but the lady wanted to get rid of it so i made a offer of R1000 more or less $90, and got it. This one also got a cone sitter and looks better than the previous one, but again no manual with it, some non working parts, i don't know where to start with it and don't want a repeat of the last one. Hubby surprised me with a brand new even bigger one, paragon, automatic, so now this newby sit with all the toys but to scared to start it and don't know where to start. Especially the new one i don't want to make mistakes on. I will take photos of all 3 if anybody can assist me in getting started. I know so little, heard of kiln wash etc, viewed over a hundred videos but more confused after every one, plz help

#2 Marcia Selsor

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Posted 27 July 2013 - 07:47 AM

Paragon is a good kiln maker. We even have a rep on the forum Howard Arnold. Since it is new, you should have the manual.
Kiln wash is simple there are several recipes. 50 silica and 50 ball clay and if you want to dress it up add 5% alumina.
You probably wouldn't need that if you are firing low temperatures.

Make sure you have the proper wiring as described in the manual. Every else should be fine.What temperature is the slip you are firing?
Get cones for that temperature. You should have a little plate to set the kiln setter. It may be on the kiln setter possibly for stability during shipping. Nice hubby!


Marcia

#3 Pugaboo

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Posted 27 July 2013 - 07:58 AM

I too am a newbie to firing and am not sure if I can help much. You say you have a brand new Paragon kiln yes? Did it come with manuals on how to use it? If not go to the Paragon website and find your model and see if you can download the manual for it and if you have an electronic controller find its manual as well. These should give you a good idea on what to do to get started with firing your kiln and this is what I would do. Also do you have a library near you? You might find out if they have any books on ceramics to help you as well.

As for the other older mystery kilns... Do you have any idea as to their names and model and model numbers? I think that knowing that might help the more knowledgable here help you with them. If they don't have a cone sitter or controller I would get some cones and place them where you can see them through the peep holes so you can see them and when they bend to the right degree you will know you have reached the correct temperature. There is also something called a pyrometer that you can get that you slip through the peep hole again to measure the temperature inside.

As for your previous disasters I know it's disappointing and makes going forward even scarier for you. With your first attempt it sounds like you started heating up the kiln and then put your pots inside, is this correct? If so they all blew up because you shocked them going from cold to hot too quickly. Think of bisque ware as frogs, if you place a frog in boiling what it will jump out but if you put it in cold water and slowly ramp up the heat it will sit there and boil to death because it does not realize it is getting hot. So next time put your pots in when the kiln is cold and then slowly ramp up the heat so they don't know they are getting hot. This will also give them time to burn off any remaining water they might have inside as well as burn out any impurities. Bisque ware needs to be done slowly especially until you learn what your clay can handle heat wise. For bisque you can prop open the top for awhile then close it. You can also leave the peep holes open until when you place a mirror in front of it it no longer steams up that lets you know all the remaining moisture has burned off and it's safe to close up the peep holes. My kiln is very small 18x23 inches and a bisque cycle takes around 15 hours to do including a 2 hour candling (its been very wet here and I am having humidity issues) so maybe you went too hot too fast the first time and then the second time maybe not long enough? It's really hard to tell since you don't know what temperature you went to. The popping and cracking after you removed them from the kiln is most likely dunting which is caused by thermal stress, you can look it up online and there are much better descriptions as to what causes this and how to prevent it.

I really think you would benefit from getting a couple basic books on ceramics they would fill in so many of the holes in your knowledge and I think make you more confident in what you are doing. I'm not sure if I helped at all but hopefully I haven't confused you even more! The real pros here I am sure will chime in with better answers.

Don't give up pottery is amazing and when you open your kiln for the first time and have fired a load successfully you will forget all about the trials and tribulations that got you there.

Terry
The world is but a canvas to the imagination - Henry David Thoreau

#4 Daleen

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Posted 28 July 2013 - 12:15 AM

Thanks for all the advice, i did a test fire in the new kiln yesterday, manual said to take it to 1100 C and soak there for a hour, but manual did not say what increments to use, i decided to take it slow up with 200 c/ hour to 1100. All went well. But it was too hot to open last night, i will open this morning, but i only had the kiln shelves in which i used kiln wash on, think i did that wrong. The medium oven i did a test fire on as well the cone sitter is broken and the dial i am not even sure what it does, i switched it on and within about 30 min it was already glowing red hot, i put in a 04 cone on the shelve so i can see when it will bend, that oven too was too hot to open but looking through the hole i can no longer see the cone, so not sure if it melt away totally, but no matter how i turned the dial on that mystery kiln it just went hotter, finally after about 3 hours i just switched it off at the plug so it can start to cool. I think this oven needs some type of temp control system. Going to the factory this morning i will take some photos and try get the name off the mystery kiln. Lol i think we just named this little kiln, her official name is Mystery now on kiln wash, i got a packet of kiln wash which i need to mix with water and then paint on, but how thick do one paint it on, its leaving a kind of powdery look to my shelves, do i whipe off this powdery susbstance or leave it on. And do i also put kiln wash on the bottom of my kiln floor?

#5 Pugaboo

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Posted 28 July 2013 - 08:14 AM

Congrats on running the test firing of your kiln. Doing it with shelves in was exactly what my book said to do so I think you did fine.

Kiln wash, I asked this question just a little while back and got lots of helpful answers. You can do a search for kiln wash here on the forum and I it should show up. A quick overview of what i was told and did is:
Mix your dry kiln wash with water to a chocolate milk consistency. Lay your shelves out face up. Use a large flat brush to brush on the wash. It will soak in very quickly and you have to kind of try different things to get it to go on as evenly as possible. Some people said they liked to use a roller so you might want to try different rollers or brushes to see which you like. I ended up using my biggest Japanese flat brush.
You do NOT put any on the sides or bottoms of your shelves and if you get any on those locations use a clean wet sponge to wipe it off before it dries completely since its easier to do so. On the inside floor of you kiln you can carefully brush on a coat of wash. Do NOT get any on your elements ( the metal wires in the walls and possible floor of you kiln) as this will make them burn out. I put a coat on the floor of my kiln and I also keep a whole shelf on 1/2 inch posts sitting in the bottom of my kiln. Doing this helps to protect the floor of your kiln. Do NOT put any wash on the walls or lid of your kiln.
Yes your shelves will have a powdery look to them and if you rub them the wash will come off, or at least mine do. I think this is normal so that if you have glaze get on them you can easily remove the glaze spots. Once you have run all the shelves through the kiln, this kind of seems to fix it on better, you can store them by placing them face to face. This protects the wash and keeps it from getting on the bottoms of the other shelves.

Good luck on finding out the mystery kilns name.

Terry
The world is but a canvas to the imagination - Henry David Thoreau

#6 oldlady

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Posted 28 July 2013 - 09:52 AM

hey, everybody else!!!    look what asking a few questions last month did for pugaboo!   aren't we all proud of what she has learned and is sharing.  keep it up, terry.


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