Finishing up the Knobs...

Here are the blank knobs that were thrown at the wheel last week, with a little bit of incising added. I will probably make most of my knobs from low fire clay, especially those I need for my kitchen that will match my tile work there. I am sure that some of the knobs will find their way into the salt kiln, however.

These were thrown from my regular stoneware clay, but it really doesn't matter since all of these will perish in the press-mold making process.

Here is the freshly cast press mold, with 8 cavities for different knobs. The clay originals removed from the mold are scrap, and need to be dumped - not reclaimed - since they are contaminated with plaster scrapings. I will let the press mold dry for a day, and then clean it by vacuuming, and also by discarding the first knobs that might have plaster scraps in them.

I have found that the easiest way to get a consistently sized knob is to extrude 1" coil, and then cut it to specific lengths to get the size ball I want. I have also extruded 1/2" coil to use for the knob shanks, and have carefully cut it to 1/2" lengths. It's firming up as I press the sized balls into the mold cavities. I am going to throw a little tool to press the ball into the mold and mark the center of the knob blank. My clay (Georgie's Cannon Beach 10) joins to itself really well, so I just score the shank bit with a serrated rib and center it on the back of the blank knob. After the shaft is joined to the knob, I wait about 5 minutes and they can be lifted out with the shaft. Cool!

Here's a finished knob made from the first press mold. Since I have been just pressing sized balls into the mold, the deeper cavities of the first mold haven't been a problem. I'll probably touch it up a little bit with plastic steel wool or sandpaper, depending on what the surfaces are like coming out of the molding process.

When the knob has dried a bit, I use a drill bit to make a hole in the center of the shank. I am going to experiment a bit with this - perhaps using one of those angled hole cutters that are used to make teapot holes. The 1/2" shank bit would have to be dried to use a tool like that - we'll see.....

I have used a 5/16" drill bit to make the holes... I think that should be big enough after shrinkage.

Here's the finished knob that Ted Juve gave me with his first instructions. You can see how the brass sleeve sits in the drilled hole. Ted says that it is very important that the knob be placed right side up after adhesive is placed in the hole, and the brass sleeve is inserted. That way, the sleeve will be flush with the bottom edge of the drilled hole, and will not vanish into the knob if the hole is deeper than the brass bit. I believe he suggested that the gluing be done on waxed paper - that will allow the paper to be peeled away leaving a tidy knob, and no knobs stuck to the worktable.

The brass gizmos and their screws come from Aftosa.

Knobs, Continued.....

Here's a nice little trim chuck for trimming the knobs I made the other day. It has a broad surface to support the knobs, and adhere to them while they are trimmed.

It will make a pleasing small vase after it does service as a chuck.

I threw it on a bat, but did not cut under it with a wire. It's essential that chucks be perfectly centered so that you can make the most regular knob possible. I like for the clay to still be wet enough to still be slightly sticky when the chuck is used. That way, the object being trimmed stays put on the chuck, but it also means that it is really easy to ding up the top of the chuck. But if it is that soft, it can easily be touched up with a moist sponge after the trimming. Anyway, it's just a chuck.

I like little trim tools for operating on knobs, lids, or other small pieces. There's not much to cut away, and I feel like I have more control while trimming.

Here are my knobs, ready for some additional decoration. I'll do that tonight, and then cast them in plaster tomorrow.

You can see that all of them have had their sides angled in slightly to make for easy casting. I don't think that will detract from their finished appearance.

Making Handmade Ceramic Knobs

As many of you know, I have been making tile for my kitchen as part of a home remodel. Most of the tile is complete, and some is installed. In my dining area, there are beautiful new oak cabinets that will have a tile counter top and back splash. I want to make ceramic knobs for these cabinets. I first saw handmade ceramic knobs at the home of my potter friend Ted Juve, in Enterprise, Oregon. Ted explained to me exactly how to make them, and gave me a small bag of the threaded brass inserts that complete the knobs.

I made my first knobs about a month ago, and cast them in plaster to make a press mold, so that I could make as many as I needed. The first knobs I made were too deep, and had to be hand cut after forming. I decided to make a new batch to carve and cast in plaster, and include this fun process in my blog.

I started out to throw some new knob blanks off the hump with my regular stoneware clay. I brought up a narrow column of clay, and formed a small knob with my fingers that was about 2 inches across. I added a little dimension to it, based on which of the first knobs I liked. The idea is that these new knobs will be just about the size that I want the finished knobs to be, accounting for shrinkage, so that I can just cut the knob to the finished size with a wire while it is in the press mold. I plan to shape the sides of the knob blanks when I trim the knobs in a tiny chuck later in the process. This will eliminate any undercut that might complicate the plaster process.

You can see that I am cutting the the small knob off the hump of clay with a thread tool. This is a small bamboo knife - about 5 inches long - with a hole drilled in the rounded end. Then, a piece of stout linen thread (buttonhole twist from the fabric store also works....) is threaded through the hole and tied. I like about 6" of thread.

I use the bamboo clay knife to place the knob blank on a board to dry a bit for trimming.

These knobs are finished by adding a 1/2 inch plug of clay at the back, and drilling a hole about about 1/2 inch deep into the extension to make a shaft to receive a threaded brass sleeve after firing. This permits the knob to be attached to the cabinet door just like you attach those boring (and expensive!) knobs from the hardware store.

When these knobs have dried a bit, I will trim them and carve a little extra pattern into them. After that, I will join a section of extruded coil to the back to form the shaft. I am going to glaze these with the green lowfire glaze that I have used for my tile project, but also plan to finish some in the salt kiln.

Hmmmm........ that will be fun.

Tile Making for My Home

For the next month or so, I will be creating tile for my own home. I'm going to be making a door surround for my front door - a 12"-14" border that will wrap both sides and the top of the door. I will also be making decorative tiles, back cove, and bullnose molding for a kitchen tile installation. I made most of the field tile about six years ago - about 80 square feet. A big new kitchen window and some new cabinets in my kitchen are a serious incentive to complete the project.

I have a slab roller, extruder, and glaze spray booth, all of which will be used to complete the tile. Because my pugmill is filled with the high-fire clay that I use for my production salt-fired pottery, I will not have the luxury of recycling the tile clay with the pugmill. I'll be working hard to keep waste clay to a minimum in my process.

Here's a picture of my slab roller and it's attached table, with work in progress. I like to roll my tile out on Slab Mat, a paper product made for the use of potters. I used to use canvas, but always wanted to take the canvas texture off the tile. The Slab Mat also reduces clay dust in the studio, which is good for me and my dog.

You can see lots of boards around the table... there are 12" x 24" drywall boards for separating and preliminary drying of the tile. There are also 24" x 24" boards which I use for moving tile around and for final drying.

I've been making tile for about 15 years, but continue to learn. My process is pretty much based around the equipment I own, and I know that there are many ways to make beautiful and functional tile. Years ago, I attended a tile making workshop presented by Frank Georgini, and I still consider his tile-making book to be one of the best available.

The first step in making tile, for me, is to get the bagged clay to the right stage of dryness. I check the bag of clay, and if there is any sheen of visible moisture, I open the bag and allow the clay to dry a bit right in the bag.

I will be using a low-fire talc body for my tile project; one with which I have had lots of experience. Because I have used Seattle Pottery Supply's LF-06 for a number of projects, I have several glazes that fit it very well. I have found the tile that I have made with it in the past to be durable. And, because winter temperatures are mild here in western Oregon, and since my new front door is tucked back under a covered porch and will not be exposed to the weather, I think that the low-fire tile will be fine for an outdoor installation. I will bisque and glaze fire both to Cone 04.

I use a large clay cutter to divide the block of clay into 3 even slices. Here, you can see two bags of clay cut and set on edge to dry. I like to work with clay that is as dry as possible. The drier your clay is when you roll and cut it, the fewer "dings" that there will be on your tile to remove later. The clay should be much, much drier than any clay that you would throw on the wheel.

It's a good idea to keep track of how you divide your bag of clay. When making tile, a potter should work toward forming slabs that have the smallest amount of waste possible. The stiff tile-making clay is simply no fun to wedge for reuse.

I cut my block into thirds, then stretch the stiffened blocks to exactly 15" long. When the 15" block is turned crosswise in the slab roller, and thinned to 1/4", I get 6 tiles that are 7.5" square with less than 1/2" of waste on each side. I worked all this out after making over 500 tiles of the same size for a mural installation at a local school. Right now, I am just making about 100 tiles for accent use. The main tiles for my kitchen job are 4" square.

In my next post, I will go into some of the techniques I use to make flat, regular, tiles. I know that sounds deadly dull, but it makes the tiles more beautiful and serviceable, and much easier to install.

Making a Handbuilt Spout

First, a template is used to cut conditioned clay into a conic spout-shaped form. The clay is softer than what I use for most handbuilding - this will permit the spout to be curved without any cracking of the clay. The clay should be just a tiny bit over 1/8" thick. When a wheel-thrown spout is made, the wall section naturally tapers from the bottom to the top. To replicate this thinning of the spout wall, I use a dowel to roll a small taper into the entire spout, thinning the top 1/3 of the spout just a bit. After this secondary thinning, I again trim the spout blank with the template.

This will help to make a more refined pouring tip possible later in the process. The template has been made by trial and error - rolling my wooden mandrel on the sheet PVC I use for patterns - and then using the side of the mandrel as a straightedge. I do make the attachment end of the spout a bit wider than the natural size of the mandrel. The template is about 10"long. The best mandrel I have was made of oak by a potter in Eugene, Dan Schmidt. I believe he went away to ceramics grad school.... correct me here, Eugene blog-followers. The Big Ceramic Store on line sells a mandrel but the proportion isn't right. I have had some made by a local woodturner that I use for my workshops.

Using the brayer, I thin and bevel both long sides of the spout blank. This allows a neat, thin join to be made. It's good to thin and bevel in several passes, working in opposite directions and making an effort not to distort the spout blank. I like to work on a thick pad of newspaper, since I don't want any canvas texture imparted to the pieces.

I also thin the tip of the spout a bit more with the brayer.

Now, I score and moisten the top edge of the spout blank on the paper in front of me, taking care to not cut or damage the thinned edge with my serrated rib. When the top edge is prepared, I turn the spout blank over on its' long axis so the other long edge is at the top. I score and moisten that edge as well, so that and inside and an outside edge is prepared.

In this image you can see each edge prepared for joining.

I lay the mandrel onto the prepared spout and begin to shape the spout to the mandrel. It must be done carefully to prevent marking the spout blank with your fingers.

With one side conformed to the mandrel, the spout blank can now be wrapped around the mandrel, taking care to match the pouring end nicely. This takes a little practice. It's okay if your mandrel doesn't extend all the way to the tip, you can use your fingers to press the tip into a neat join. Do not cut the tip at this point or try to shape it. That can be done much more easily quite a bit later, even after the spout is placed on the teapot.

Here's a pic of a stage in spout making where proper alignment of top and bottom edges can be seen. I don't apply any lengthwise pressure to the joint - I just sort of press with fingertips to mate the two edges.

Here's the spout with sides all joined up. The spout can be very gently twisted to straighten the line of join. The line can be "erased" with a finger tip, but a bit dryer stage. I have always preferred to leave the line be, or even make it part of my overall design. Textured clay can also be used for spout making. In that instance, trying to remove the join line will obliterate the impressed pattern.

In the case of this spout, I use my brass dot-roller to decorate the join.

When you are decorating your spout, or looking at the join line, it's important that the joined edge end up on the upper surface of the spout. This is because the bottom of the spout will extend out further than the upper edge, and needs to be stronger and have the internal integrity of "whole clay." I sometimes even moisten and "pull" the bottom edge of the spout a tiny bit to create better pouring properties, and a traditional look.

Now, holding the spout in both hands, carefully impart a graceful curve to the finished spout. What you see in the image is about right for the teapot bodies I will be making. You will have to experiment with your own forms. I usually make spouts the day before I make teapots, and allow them stiffen slowly. I like to put them in a plastic shoe box, cushioned in dry cleaner plastic, with the lid on tight. It is possible to join a pretty soft slab to a teapot body, but I can get a neater look with a spout that has "rested" a while.

When the teapot body is ready, the spout will be cut with a single long stroke and joined to the body. That will be next.

Just a note about the mandrel and it's use.... most potters actually pull a hollow spout over the mandrel by twisting a cone of solid clay onto the form and pulling a hollow spout down the tapered tool. I tried about three times to do this with appalling results, gave up, and started handbuilding spouts with the mandrel as an aid. At that point in my clay career, I couldn't pull a handle either, so maybe I should try again.

I have seen Steven Hill pull a spout on a pool cue sprayed with WD-40. Pretty impressive!

State of the Reliquary and Notes from the Workshop

Here are some cups and teapots made by potters at the workshop in my studio this past Saturday. White earthenware clay - LF06 from Seattle Pottery Supply - was used to build these pieces. Participants worked with conditioned clay slab, stamps, rollers, and texture mats to form and decorate their pieces, and all pulled handles on their teapots after practicing handles on their cups. We all decided to call the process "handle smoothing" instead of "handle pulling".

I'll be posting the whole teapot making sequence on the blog in the next week or so. In the meantime, here's the low-fire glaze recipe that we talked about during the workshop and saw on pieces in the studio. This is an extremely well behaved, paintable Gerstley Borate glaze that comes from Gail Kendall. It should be thick and goopy - about the consistency of yogurt, and is easy to paint on pieces. I like to use one of those cheapie disposable brushes from Home Depot, but any wide flat brush with coarse bristles is fine.

You can paint this glaze inside a cup fairly easily, but it is a problem to get it inside teapots or tall pieces, or very small pieces. I use Georgie's lowfire base glaze for pouring inside pieces. I am not sure if this glaze is still available, but every pottery supply house offers a dry lowfire clear. These glazes are often hard to dip on smoothly, and sometimes have unpleasant opaque areas where the glaze is too thick. The Georgie's base glaze is very nice sprayed on the outside of pieces, but I could never get a good surface by dipping or pouring. But it makes a great liner glaze, and is completely compatible with Kendall glaze. Over or under, the two glazes melt together smoothly. Here's the recipe:

Kendall Paintable 04 Glaze

55% Gerstley Borate

30% EPK

15% Silica

Rich Green - 8% Copper Carbonate

Cobalt Blue - 2.5% Cobalt Oxide

Inky Blue - 6% Copper Carbonate + 1.5% Cobalt Oxide

Rich Yellow - 6% Rutile

Cream - 3% Rutile

Warm Clear - 1.5% Rutile

Ochre - 7% Umber

Medium Blue - 2.5% Cobalt Carbonate

Mason Stains - 4% typical, more required for all pink, purple, red

The "Cream - 3% Rutile" variant is what was used on the pieces seen in my studio.

This glaze should be thick! If you try to thin it enough to pour, it will not yield a satisfactory surface. I paint three thin, even coats on each piece, taking special care under handles and around details. It will crawl if it is too thick. Let each coat dry before applying the next.

The slab for the reliquary is bisque fired and ready for the mat to be made. I will be doing that later today, and will also be testing three different seal/release products.

It was a very close fit going into the kiln.... but I wanted the largest slab possible. I have tried standing the slabs on edge for firing, but they bowed in firing. I was still able to make useful mats from those slabs, however.

Some other handbuilt pottery....

Here are some really big jars that are handbuilt. The shoulder and lids for these are thrown and added later.