Tuesday, September 21, 2010

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.

Saturday, March 6, 2010

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!

Tuesday, March 2, 2010

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.

Saturday, February 27, 2010

Some other handbuilt pottery....

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

Tuesday, February 23, 2010

Making a Reliquary, Part 1

This week, I am beginning an interesting new ceramic piece. I am making a latex texture mat, which has text and imagery that will be incorporated into a funereal reliquary. The reliquary will be used for the ashes of two much-loved and exceptional people, husband and wife, who requested that their remains be joined after their deaths and interred at a wild and beautiful spot on the Oregon coast. These two individuals were Floyd George Steele, and Dorothy Jane Petersen Steele, my father-in-law and mother-in-law.

The design of the imagery records their shared, lifelong appreciation of music, and F. G.'s passion for mathematics. D.J. loved plants and flowers, and enjoyed having them in her home. The names of their six children are part of the design.

The imagery will be incised into a 1/2" thick slab of white, grogless, low-fire clay. I like Seattle Pottery Supply's LF06 for this use. Like all talc bodies, it is a pain to recycle, but has many other fine properties. The slab was cut to the largest dimension that will fit into my Skutt 1227 kiln. Once the imagery is complete, the slab will be carefully dried before bisque firing to Cone 04. After firing, a 2-part latex mixture will be applied in three coats, and a mat will be lifted. This mat will be used to texture a slab for the body of a reliquary, and can then be used to create keepsake pieces for family members.

In the image at the top of the page, you can see a quilter's oval template laid out to align with a center mark on the clay. I will use this oval to define the text area, and also to inscribe consistent and correct lines in the clay.

Lettering with stamps must be done well before carving can take place. For the letter stamps to work, the clay should be fairly soft. Carving can be most easily accomplished when the clay is harder than a brick of cheese.

I'm controlling the drying of the rest of the slab while the central lettering is taking place with plastic. These letters are available at Georgies, and are made of plastic. I prefer the metal letter stamps that are available from Tandy Leather, but I did not have the correct size for this project. I might have been able to get a better impression at a dryer clay state, but I wanted to get this project started since the drying of the slab can take a week or more. I have about three weeks to complete this project before the scheduled memorial service.

Lettering of the central oval is complete. Now, I will dry the slab on a piece of plywood in the open air for about four hours, until it is dry enough to begin the rest of the imagery.

I use a commonly available wire-tipped tool to incise imagery into the prepared clay. I'll take a picture of the tool I use and post it on the blog.

The floral imagery I use is part wild rose, part dogwood, and part magnolia. My own mother used a similar generic flower in her textile painting and other handcrafts, which I loved to observe in process as a child.

Here's the slab after three or four hours of pattern application. All this imagery will be refined again at a drier state. From here to bisque firing, I will cure the slab in such a way that both sides loose moisture evenly and equally. This will prevent warping during the drying process.

The finished slab is ready to be dried between layers of gypsum board. Every day, I will uncover it and have a look at it, and rework lines and letters until I am satisfied with the surface. When the slab begins to change color, I will dry it on a wire shelf so air can reach each side simultaneously. Subsequent blog posts will show the making of the mat, and the creation of the funerary vessel.

Thursday, February 18, 2010

Step 9 - Finishing the Handle

Here's where we left off in the last post, just having gently pressed the new, soft handle onto the scored spot that was prepared before the handle pulling started. The handle is very tender at this point, and it's easy to deform it with a careless gesture.

You can see the handle extending past the bottom of the cup. I let the handle form a bond to the cup while I do a little refining with a small sponge at the top attachment.

I have pinched off all but about an inch of the extra clay at the bottom of the handle. This will be enough to make the little bunp that I like at the base of my handles.

I form the little bump by folding one side of the the extra handle stock to the middle, and then folding the other side over it. I fiddle around with my finger until I get it like I want it.

This cup handle is related to handles that I have seen on early American pewter cups and pitchers. I feel that the little bump at the bottom balances out the volume of the curve at the top of the handle, and makes visual sense to me.

I dry these cups right side up. If you invert the cup, the handle will dry faster than the cup and be in danger of cracking off. In summer, I cover them with plastic for a couple of days so handle and cup can slowly dry together.

Step 8 - Pulling the Handle

Here, I am holding the cup with its' handle stub attached perpendicular to the floor. What you can't see is that my right hand is in a container of water. First, I use my wet thumb to refine the join area at what will be the top of the handle. Then, I dip my hand in water, and then begin to stroke and smooth the handle blank. I am not pulling it downward- that will happen as the blank is wetted and smoothed. The hand doesn't want to make a symmetrical handle - it isn't a symmetrical apparatus itself - so differential pressure will have to be used to each surface of the handle. I really don't know how to describe that... you will have to experiment. This does take practice - I started really understanding how to do it after a long workshop with Ellen Shankin, where many, many handles were attached. Before beginning to work the handle, I wet and scored an area at the base of the cup where the handle tail will be attached. I did this to create a target for placement, as well as to strengthen the eventual join there.

Now, you can see that how the handle has lengthened and thinned as I have smoothed and shaped it with my wet hand. At this point, you can add a groove with your thumb if you like that look. Don't be afraid to experiment! I almost always have an inch or two of clay to pinch off at the end. If you should need to reattach a new handle stub, scrape the top of the cup smooth and set it aside for a little while. The cup clay with be softened from the first attachment, and it will need to stiffen a bit. If the handle stub has been properly prepared, this shouldn't happen.

Here's the cup and handle ready to finish. You can see the nice taper that has been created by the wetting and smoothing process. There is also a taper in the other plane, but I didn't think to take a picture of it. Please note that the cup has been held parallel to the floor throughout this entire process. I find that this makes a smooth and attractive attachment point much easier to make.

Hold of the tail of your handle and give it a small tug to pull the handle down to the point of attachment. I score the bottom of the cup where the attachment will be made before I begin to wet and smooth the handle. Take special care that your handle is attached straight down - parallel to the long axis of the cup. I still have to really concentrate on this to make it right. The handle is pretty wet and weak at this point, and cannot be taken loose and moved, unless there is a lot of clay still in it that can be pulled down in a second effort.

Press the soft tail of the handle carefully onto the scored clay at the point of attachment. Finishing the handle will continue in the next post.

Friday, February 12, 2010

Step 7 - Attaching the Handle

I can hear the groans about pulled handles resounding through cyberspace. Potters, this can be learned easily with practice.
Start with some nice, fresh clay - not reclaim. Roll out a fat coil about 1.25" in diameter for these big mugs. If your clay starts to flatten out, twist each end in opposite directions and it will roll round again.

Now, working from both sides, firmly pat the coil into a flattened elipse. You can see the section that we want in this image... this is the general shape of the cup handle that I want on a mug like the ones we have been making.

With the serrated rib, score deeply into an area about 1" x 1-3/4" just to the right of the vertical join. You don't want it sloppy wet - just scraped up a bit. If your cup, or any piece upon which that you wish to pull a handle, has begun to dry at the top and is changing color, do not attempt to pull a handle. You will have cracking! The cup will have already begun to shrink, and when the handle starts to shrink as it dries, it will pop right off. Be especially careful in summer....

Take your handle blank in your left hand (sorry, Lefties, you'll have to reverse a lot of this) and working from the center out with short strokes, score the handle attachment plane. A nice bead of worked clay will extend over each edge if you do it right.I have just pushed the handles onto the cup bodies in the picture below. Handles WANT to stick to the cup! I can't emphasize enough how important it is to have both cup and handle at similar stages of drying is for this process to work right.

Use the tip of your finger to smooth the join where the handle meets the cup. The extra goo that was scuffed up with the rib makes it really easy. I like to set cups aside for at least 5-8 minutes so the attachment can develop.

The handles appear to be too large, but we want a nice, large base of attachement.

Here's the handle all ready to be pulled into it's final form.

Thursday, February 11, 2010

Step 6 - Measuring and Attaching the Bottom

I have a set of nifty little round cutters - Ateco brand - that I purchased at a cookware store in Portland. I'm sure you could get them on the net.... I pick out a likely one and check it against the diameter of the cup, and then cut a clay bottom for my cylinder with it.

Before I had the cutters, I had a small collection of round things that I used as templates; mostly jar lids and lids from plastic containers. You can easily size slab for a specific template diameter by measuring around the circular object with a tape measure. The measurement is usually about 1/4" longer than the slab needs to be. A little patience with the trial and error process will yield a nice fit, just be sure to jot down what slab size is required for a particular circular template.

Now, moisten and score both the bottom of the cylinder and edges of the circular bottom with a serrated rib. It's good to have a close fit, but if the bottom is a bit large be sure that the cylinder is centered on it. After the bottom begins to adhere, flip the cylinder, which I guess is now a cup, over. You can gently move the cup around as needed to center, or adjust the edges. It will slide on the film of water for a few minutes after it is set on the bottom.

I usually attach the bottom with the cup upside down. You can see the neatly fitting bottom ready to become part of the cup below. Just a little smoothing with the finger, and perhaps a careful sponging with a little piece of sponge is all that is needed to finish the bottom.

Just a swipe with the finger
is enough to seal the seam.

A tool can be used to firm the
vertical join.

Now, the finished cup can be set aside to stiffen in preparation for pulling a handle. If the top rim is firm and level, the cup can be turned upside down. If it is soft, cover the cup with plastic so the mug can firm up slowly. I often pull handles on hand-built mugs the day after I form them.

Step 5 - Making a Cylinder from the Cup Blank

I use a section of paper mailing tube to "train" the cup blank to be round. I don't wrap the blank around the mailing tube, I drape it over the tube in a horizontal position. I support the tube with my left hand, and with my right hand press the slab to conform to the curve of the tube. It's important that each of the sides is pressed into the form of the tube.

When you have curved the entire piece, set the tube and curved blank down on what will be the bottom edge of the cup. The top will have a nice rounded rim, while the bottom will still have square edges. Slip the tube out of the cylinder and set it aside. Position the left side of the cup blank, which has scoring on its' outer edge under the right side of the cup blank, which has scoring on its' inner surface. The cylinder should be sitting level, and the tops of each side should be level, or close to it. Gently press them together, and let the clay surfaces adhere for a few minutes before smoothing the join further. Just your finger will do at this point, a tool can be used to finish the join more completely when the piece is at a dryer state. The tube can be reinserted into the cylinder and used to resist pressure from your fingers, or the brayer. Be gentle and don't deform the join - the clay has a will to stick to itself....

Step 4 - Preparing the Edges of the Slab Blank

Using a serrated rib dipped in just enough water so it can be seen wetting the surface, carefully score the left edge of your cup blank. Be careful not to distort or thin the edge of the slab - we just want to give it some tooth so it will grab onto the other side of the lap joint. I don't use slip to join clay. If the slab is at the correct stage of dryness, it will easily join to itself with water only. I do use defloculated water to join porcelain in the summer months, but don't really know if it is necessary.
Now, turn the slab over and score and wet the back side of the right edge, take care not to stretch the edge. The edges should each have approximately the same taper.