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Warm glass can be a daunting craft for beginners. Glass kilns can be expensive, their firing schedules are more complicated than basic bisque and glaze firing, and even though you can do a lot with basic tools, more advanced techniques require specialized tools. So what are some basic glass projects you can do in a ceramic kiln?
Firing Glass with Pottery
The easiest glass project may also be one of the most popular and best looking. Take any ceramic vessel such as a plate, bowl, or cup - anything that can hold liquid – place colored glass in the bottom and fire as you would normally (cone 6 is recommended). Any glass will work, but glass made for fusing is more likely to retain its color (reds will almost all turn brown regardless). Glass will expand as it is heated and some glasses will start to bubble or foam in the kiln, so start with one or two pieces and then experiment with more as you grow more comfortable with the technique.
Remember, melted glass will always seek the lowest point, so patterns carved into the bottom of your vessel will fill with glass first, which can make for a very attractive effect.
Glass can be used on the clay body or with glaze. Each combination of glaze and glass will produce a different result. One great way to experiment is to make a lot of candle holders. Either dishes or bowls just big enough for a votive candle can be made by the dozens and will fit nicely in the odd spaces in the kiln. Just be sure to take notes of the glass/glaze combinations and number each piece before firing because the results may be unexpected.
Note: Melted glass in pottery has surface-level cracks that can collect dust, bacteria or mold and is therefore not considered food safe.
Slumped Bottles are some of the most popular fused glass products. They are cheap and easy to make even in a manual ceramic kiln, just be sure to position the bottle somewhere visible through the peephole and keep a close eye on it, otherwise you risk going beyond slumping and you end up with a glass puddle. Be sure to read our tips on bottle slumping to get the firing profiles.
It’s no doubt that gold is super “in” right now. I’ve seen a huge influx of orders for pieces with gold accents. People love the shiny finish! Admittedly, I’m a sucker for it too. I’ve experimented with different types of glazes to get this effect – high fire, low fire, non-fire. The trick is consistency with the finish as well as making sure the pieces are food safe. You can go the traditional gold leaf route, but who wants to spend that kind of time?
I’ve found that the Duncan Precious Metals Overglaze is an awesome product and can be used in a variety of ways to get that shiny gold everyone is swooning over. This overglaze is applied as a third firing. So, you bisque your piece, glaze fire it and then apply the luster to the piece. The first step is to decide if you want a shiny finish or a matte finish for your gold or silver accent. For a shiny finish, make sure you glaze your piece with a very shiny, high-gloss glaze. The gold will be super shiny, almost like a piece of real 24 k gold. For a matte finish, glaze with a matte finish glaze. The gold comes out more of a bronze when you do this.
Applying overglaze is fun but tricky. I find myself praying a lot to both the Glaze Gods and the Kiln Gods when I am working with it on my pieces. I’ve had a lot of blunders, but through it all have found a few tried-and-true tips to make sure the end product comes out beautifully 90% of the time (as we all know, nothing is ever 100% guaranteed when you are working with glazes and ceramics).
Overglaze Tip 1
Prep the area where you want to apply the overglaze with rubbing alcohol and let it dry completely before applying. Do not touch the area after prepping as adding any oil or other elements from your skin could corrupt the area.
Overglaze Tip 2
Use a very clean brush for application – and pick a brush that will only be used for applying the luster overglaze. I like Duncan brushes. You don’t want to contaminate the brush with other chemicals and elements from other glazes. This is a sure fire way to ruin the piece. When you are done with this overglazing session, be sure to clean your brush thoroughly with Duncan Essence Overglaze Cleaner. It’s a lifesaver!
Overglaze Tip 3
Apply only one coat of the overglaze if you can. If you need to go back over an area, do so immediately when the glaze is still wet. Once it dries, it will clump up or rub off, creating holes in the finish. I’ve also found that it turns to a dusty matte finish if you do this. Single, uniform strokes are best to achieve the opaque and shiny finish. Too little glaze will produce a purple finish, and too much will chip off or crack. It’s an art and a science and you need to play around a bit to get it just right. Test, test, test!
Fall is in full swing, and we've been receiving a lot of questions about whether or not leaves could be used to make impressions in clay. Leaves are used in pottery all the time, but we have a few tips that might make the process easier.
Thick leaves with deep veins make the best patterns. Otherwise you don't get much texture and it just gets filled in by the glaze.
Some people find artificial leaves actually make better impressions because they are thicker, and sturdy so they can be used again and again.
If you use live ones, it works best if they are still green (not dry), so they don't crumble. Soak them in water overnight to make them more pliable.
A couple ways to save leaves for later use:
- Paint both sides with shellac.
- Place them flat in airtight plastic bags and put in the refrigerator or freezer.
If you have trouble getting the leaf out of the clay once you've pressed it in, use a pin or needle tool to pry up a side. Or you can actually leave (no pun intended) them in and they'll just burn out in the kiln.
If you get a pattern that isn't very deep and you want it to be more noticeable, there are a couple things you can do with glaze to make the pattern more noticeable.
- Use a transparent glaze so it pools thicker where your impression is, and it will be darker where it pools.
- Brush on a stain or oxide, then wipe off the top surface, leaving it only in the impression. Then cover with a transparent glaze.
- Brush some texturizer onto the leaf impression. Wipe off the high surfaces, leaving the texturizer only in the impressed portions. Dip the whole piece in glaze. You will get a different texture where the leaf pattern was.
You can also use leaves as masking, painting underglaze or glaze around the leaf.
- On leather-hard ware, we've found it works best to soak the leaf in water, then stick it on. Paint around it with slip or underglaze.
- On bisque it is difficult to get the leaf to stick well so you can paint a good edge. You can apply the leaf with a thin layer of glue; sticky spray adhesive works well. Then carefully stick it to the bisque and paint. The leaf and the adhesive will burn away in the kiln. Be sure to have good ventilation for this.
Potters use clay in many forms. We have a huge selection of pugged clay and slip, but sometimes commercially available clays don't offer features that a potter may be looking for such as being locally sourced, or a certain plasticity, glaze fit, or strength. Mixing your own clay body takes a little experimentation and some trial and error, but has the potential to yield high rewards.
Clay Basics – Local Clay
Pure clay is also known as hydrous aluminum silicate (Al2O3-2SiO2-2H2O) and makes up nearly 75% of the Earth's crust. Because it is so common, the most basic clays can usually be found within walking distance of your studio. The easiest places to find clay are by the sides of rivers and streams (look in the outside bends where the water has eroded the topsoil) or 5 feet below the surface of the ground (especially under soil that is sticky).
Once you hit clay, you can do some basic tests to determine if it is usable. First: try to roll a coil. The more plastic (flexible) the clay, the thinner the coil. Second: rub the clay between your fingers. If it feels smooth and round, it will throw easily. If it feels sharp and gritty it will be more difficult (but may have some desirable properties when fired).
After you dig up your clay, cut it into 1-2 inch pieces and put it in a bucket of water for 3 days (or until the clay is fully slaked). Mix the clay and then pass it through a 30-50 mesh screen to remove unwanted pebbles, sand, and other materials. Then pass it through an 80-100 mesh screen to remove finer grit. After drying to the desired wetness, the clay will be ready to use.
You will need to experiment in the kiln to find the right bisque and maturation temperatures, as well as shrinkage and glaze fit, and you will most likely have to add additional clay and chemicals to achieve the desired final properties.
Here are some basic troubleshooting tips to help: if your wet clay doesn't hold its form enough, add ball clay. If your clay is too plastic, or too sticky to work with, add fireclay. If your clay is too dark, matures at too low a temperature, is brittle when fired or shrinks too much, add kaolin.
Below is a tried and true earthenware recipe for use with local clays.
You’ve probably heard of oxides, but you're probably wondering how they are used.
Well you've come to the right place! Here are the top 10 ways to experiment with oxides.
- Brush oxides on greenware, bisque and/or glaze.
- Make some slip and add some oxides to create colors. To get more uniform colors mix well. To get more random, blotchy colors, don’t mix too well.
- Brush oxide wash over an unfired glaze, then fire. Be very careful when handling as you may smudge the oxide.
- Brush oxides on, then apply glaze. Best to dip or spray to avoid brushing the oxide off (and if dipping, best to put some glaze aside so oxide doesn’t contaminate your whole batch of glaze). Generally, the stronger the oxide wash, the more it will bleed through the glaze.
- Mix ball clay with your oxide/water. This gives a better consistency and tones down the color.
- Brush a couple different oxides on, overlapping in areas.
- Sgraffito. Brush on oxide. When dry, scratch with a sharp tool through the oxide to show the clay underneath. Cover with transparent or translucent glaze. Or do the same thing with oxide over unfired glaze.
- Spatter wax on the surface, and paint the oxide wash over that.
- Use other masking techniques, such as torn, wet newspaper, and paint an oxide wash over it.
- Sprinkle a variety of different oxides on a newspaper. Place leather-hard objects onto the oxide mixture (for example, a piece of tile). Or use a piece of Styrofoam or a sponge to pick up the oxide and transfer it to your piece. Keep the pattern as it lands, or smear it around. In this case if you’re once firing you can add glazes. Otherwise bisque and apply glazes; the oxides will still interact with the glazes when fired together.
Keep in mind, Oxides are strong colorants, so a little bit goes a long way. In a solution you will probably only want about 2-8% or you will end up with black.
Be sure to use a respirator or mask when handling the dry oxides and remember that using oxides like this will provide unpredictable, but sometimes beautiful results. Test and take notes!
We here at Big Ceramic Store love pottery just as much as you do, so when our customers send us some of their spectacular creations, we get very excited!
Check out these two inspiring pieces from our friends over at Chrysalis Pottery:
Have a piece of your own you'd like to share? Leave a link here in the comments!