I would make it decorative, not structural, no matter what type of clay you use. You could design it to cover a structural member. Use construction adhesive to mount it. A groggy body would be most forgiving, or paperclay.
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Posted by neilestrick on 24 June 2016 - 10:50 AM
You can do the same test by adding the silica and kaolin to a specific amount of wet glaze, then calculate it out for the big batch. I would take a pint of wet glaze and test increments of 5g each silica and kaolin up to 25 grams each. That will likely fix this batch, but you'll need to run new tests with dry material for the next batch.
Posted by neilestrick on 23 June 2016 - 08:07 PM
I would try adding equal parts silica and kaolin in 2% (each) increments until the crazing stops. To do this: take 200g of dry glaze and add 4g each of the silica and kaolin, add water and mix well with a stick blender, then dip a tile in it. Then add another 4g of each, blend and dip a tile. Continue until you get up to 10% (20g total each) of each. Fire them all off and see where the crazing stops. You could do this by just adding silica, but it will alter the silica to alumina ratio. By using both silica and kaolin, the ratio should stay pretty close to the original. Without knowing the formula of the glaze, there's not much else that can be done.
Is the crazing big spaced out cracks or little close together cracks?
Posted by neilestrick on 21 June 2016 - 02:26 PM
Leather hard would be best, but it also depends on how you're applying it. Spraying or brushing you could do either way. Dipping should be leather hard. Be aware that your glazes will not go on the same, drying time will be really long on leather hard, and some glazes just won't like it. It's probably going to take a fair bit of practice to figure it out. Personally, I would just fire the second load a little emptier and not risk ruining some perfectly good pots with a process you're not familiar with. Electric kilns are cheap to fire, so you're not wasting much energy by not having it totally full.
Posted by neilestrick on 16 June 2016 - 12:28 PM
The K26 will probably be less crumbly. Although they can withstand the higher temps, they don't insulate quite as well, although probably not enough to make a big difference. I would go ahead and use them because you'll get less shrinkage of the hot face, which means the arch will last longer.
As for cutting, any power saw can do it very easily, however it will destroy the blade and make a ton of dust. The dust can get into the motor of your saw and ruin it. If you've got an old chop saw I would use that rather than risk your table saw. They also cut very easily with a hand saw, and setting up a jig would be easy.
Posted by neilestrick on 13 June 2016 - 02:00 PM
If both elements are in the same ring, then you probably have a dead relay. There is no right side up or upside down in thermocouples. You just have to make sure you have the wires connected properly.
But don't the new thermocouples have one of the prongs with a red mark on it so it is matched with the red wire??
Yes, exactly. But it doesn't matter which direction it's facing as long as all the connections are correct. Just make sure red is negative and yellow is positive. If your thermocouple doesn't have a red mark for some reason, you can identify the negative (red) side because it is magnetic.
Posted by neilestrick on 13 June 2016 - 10:51 AM
To test % increases- take 200g of the base glaze plus the lowest % of colorant, mix with water and blend with a stick blender. Dip a tile. Add the amount of colorant to get to the next %, blend and dip a tile. Repeat until done. The last tiles will be slightly off from the exact percentage, but it's more than accurate enough for a first round of tests. For the second round I'll run exact percentage tests for my target tile plus 1% above and below. It only takes a couple minutes to do a full blend from 2-10% in 2% increments.
Posted by neilestrick on 09 June 2016 - 01:15 PM
Suppose it takes 5 minutes to sharpen a trimming tool, which is pretty quick if you're planning to do a good job. In reality I would probably spend closer to 10 minutes to get it done right, so it cuts without leaving lines. But let's stick with 5 minutes for this argument. In that amount of time I can throw 3 mugs or 3 tumblers or 2 bud vases, or 1 medium vase, etc, which comes out to about $22 worth of production done in the amount of time it takes to sharpen a $5 tool. Even for a $14 Dolan it's not worth the time. Throw it away and buy a new one. Support another business.
Posted by neilestrick on 08 June 2016 - 08:51 PM
90% of businesses fail in the first year because they don't have enough cash to keep them open while the business grows.
Don't forget the cost of having the electrical work done for the kiln. That can range from $100 to $1500 depending on your setup. Get lots of quotes.
Also check with your municipality on the rules about home businesses. In the 'burbs where I live there are a lot of rules, like the business can't take up more than 25% of square footage of the level of the house that it's on. Lots of rules about roof and wall penetrations, signage, and customers coming to the house, too. Basically, they don't want the business to impact the neighbors in any way.
Also check with your insurance company regarding your kiln and the business in general. If it's truly an official business, then you should have business insurance. Your homeowners policy may not cover anything business related. I would set up the business as an LLC- it's cheap and easy to do in most states. Business liability insurance is also pretty cheap in the big picture.
Posted by neilestrick on 08 June 2016 - 09:16 AM
Definitely check out the cost of having them printed for you. Depending on the volume you need, it may be more cost and time effective to not do them in house. The price per decal can be quite low when buying in quantity, and you won't have to deal with the maintenance and upkeep of the machine, and the time it will take to learn how to use it and get everything to work properly.
A good resource: http://rothshank.com...ecal-resources/
Posted by neilestrick on 07 June 2016 - 04:24 PM
You can overlap just about any two glazes and get something interesting. Amaco has been nice enough to do the testing for you. Some glazes don't play nice together, but most will. As for what they will do, it depends entirely on the formulas of the two glazes. In general, the combination will be more fluid than the original glazes, though, so you have to leave room for them to run. As you can see from the samples, color theory does not really apply, because we're dealing with chemical reactions, not pigment mixing. Also, glaze A on top of glaze B will not necessarily look the same as B on A. I have a board in my studio that shows all the double dipping combinations for all 14 class glazes, so 196 tiles.
Posted by neilestrick on 24 May 2016 - 01:15 PM
Ceramics= pretty much anything made of clay materials. Technically, anything made from aluminosilicates.
Pottery is ceramic. Little figurines are ceramic. The porcelain parts of spark plugs are ceramic. Knife blades can be ceramic. Toilets and sinks are ceramic. Tiles are ceramic. The slip cast figurine branch of ceramics has taken the term to mean what they do, and call things made with moist clay 'pottery'. People who work in figurine ceramics are the only ones who use the term 'ceramics' they way they do. Everyone else uses the much broader definition of the word. If you read the magazine 'Ceramics Monthly', there are no slip cast figurines in there. It is all potters and sculptors. Some of the work may be slip cast or made in molds, but they create their own molds from scratch.
It can all be fired the same way. There's a lot of mis-information in the figurine ceramics world about what potters do, simply because figurine 'ceramics' folks don't make pottery.
Posted by neilestrick on 20 May 2016 - 12:03 PM
Go ahead and do zone control. It's not much more money and very worth it. Don't try to put everything in the sitter box. Use a vented external box so everything stays cool. I think the easiest way to do it would be to put a box on the wall and run jumper cords to the box, like an L&L DaVinci. The cords can be hard wired at each end. For the control box connection put in a terminal strip so it's easy to unhook them when you need to do maintenance.
Use SEOOW type cords from McMaster, and put heat resistant sleeving on the wires at the kiln hookup. You can get that at McMaster, too. Get the abrasion resistant stuff or some sort of coated sleeving. All the other stuff frays really badly.
Use cable clamps at all penetrations.
The thermocouple wires can all be external.
Use a 1/2 amp fuse for the control panel.
No need to put a switch between the transformer and controller, but it's nice (and cheap).
Posted by neilestrick on 17 May 2016 - 10:46 PM
Sounds like maybe the glaze wasn't thick enough. Most commercial glazes need 3 coats, sometimes 4. You can glaze over them again and re-fire them. Fire slowly, as some clay bodies don't like to be re-fired.
I assume your mention of air bubbles has to do with thinking they will cause pieces to blow up? Not true. Think about adding handles or other attachments to pots- we score the clay, which makes tons of little air pockets which don't blow up. Steam is what causes things to blow up in the kiln. Air only expands about 1.5 times when heated up to firing temps. That's not enough to blow apart the clay. However water turning to steam expands 1,700 times. That is enough to blow clay apart. Bone dry pots have some water in them. It's impossible to have 0% moisture in the clay when it's in a room that's 30-80% humidity. So that water must evaporate at the start of the firing before it turns to steam. Pots that are thin have no problem drying completely at the start of a firing. Thick pots take longer to dry, so at typical firing speed a thick piece may not get totally dry before the kiln gets hot enough to turn the remaining water to steam, and BOOM! Kids pots tend to be thick, so they are more likely to blow up if the teacher doesn't slow down the firing or give them a good preheat in the kiln.
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