Greenbarn Potter's Supply Ltd.

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Normal Hours of Operation

Open Mo-Fr 8:30-5PM, closed Sat, Sun and long weekends.

Next closure for stat holiday is for Victoria Day, closed on May 20, and re-open on May 21.





Ordering Information


Plainsman Products


  Low Temperature Clays
  Medium Temperature Clays
  High Temperature Clays
  Other Clays
  Native Clays
  Casting Slips


  Dry Materials
  Encapsulated Stains


  Spectrum Opaque Gloss Low Fire Glazes
  Spectrum Semi-Transparent Low Fire Glazes
  Spectrum Satin Matte Low Fire Glazes
  Spectrum Crackle Glazes
  Spectrum Metallic Glazes
  Spectrum Raku Glazes
  Plainsman Dry Glazes
  Potter's Choice Cone 5/6 Glazes
  Celadon Cone 5/6 Glazes
  Moroccan Sand Glazes
  Spectrum Hi Fire Cone 6 Glazes
  Spectrum Shino Glazes Cone 6
  Spectrum Celadon Glazes Cone 6
  Liquid Brights


  Spectrum 500 Underglazes
  Underglaze Tools
  Amaco Velvet Underglazes


  Enamelling Supplies
  Enamelling Tools


  Electric Pottery Kilns
  Electric Glass Kilns
  Kiln Furniture
  Kiln Parts, Accessories
  Exhaust Systems
  Potter's Wheels
  Slab Rollers
  Hand Extruders
  Banding Wheels
  Air Brushes


  Throwing Tools
  Trimming, Turning, Cutting Tools
  Wood/Bamboo Tools
  Wire and Wood Tools
  Decorating Tools
  Glazing Tools
  Ribs & Scrapers
  Ribbon/Wire Tools
  Knives, Needle Tools, Cutters
  Sculpture Tools
  Tool Kits


  Miscellaneous Accesories
  Cork Pads
  Oil Lamp Accessories
  Dispenser Pumps
  Teapot Handles
  Bisque Tiles

Western Canada's largest distributor of pottery materials and supplies. Clays, raw materials, tools, wheels, kilns, slabrollers, books & much more.

Our continuing goal is to supply artists, potters and crafts people with great quality products, knowledge and customer service. Our staff is familiar with all the items we stock and can help you through the selection and ordering process. We will also see that your order is shipped according to your directions, or put together for pick up at our retail store in Surrey, BC.

Kilns for Sale at 60% off - oddballs need good homes!

The following two kilns are in stock, brand new in the box, and are now discounted until each are sold!

1. Skutt Scarab, Flameworking Glass Kiln, 27x16x12" inside, 240volt/1phase. $8335 reg.

- now on sale at 60% less. $3334 + tax

2. Skutt Scarab Mini, Flameworking Glass Kiln, 12x16x12" inside, 240volt/1phase. $6055 reg.

- now on sale at 60% less. $2422 + tax

Sculpture Materials on Sale!

The following items are now discounted while stock remains!

1. Roma Plastilina, Grey/Green, oil based clay, offered in soft/med/firm

- now at 25% discount. Sale priced at $19.19/2Lb block + tax

2. Armature Wire (not intended for firing within a kiln):

- 1/16" by 32' roll: now at 25% discount. Sale priced at $6.19/roll + tax

- 3/16" by 10' roll: now at 25% discount. Sale priced at $11.49/roll + tax

- 3/8" by 10' roll: now at 25% discount. Sale priced at $17.89/roll + tax

Technical Tips Blog

A black engobe transforms the floating blue glaze over it

Floating blue over black engobe

This is M340 stoneware glaze fired to cone 6 using the C6DHSC schedule. The L3954B engobe fires deep black (it has 10% Mason 6600 black stain). The engobe was applied by pouring and dipping at leather hard stage (inside and partway down the outside). After bisque firing the piece was glazed inside using the base GA6-B Alberta Slip amber base. The outside glaze is Alberta Slip Rutile Blue GA6-C (you are seeing it on the bare buff body near the bottoms and over the black clay surface on the uppers).

Context: L3954B, GR6-M, G2826R, FLB

Sunday 26th May 2024

See the magic of thixotropy as I mix a 20kg batch of G2926B glaze

In this video, I mix 20kg of glaze powder into 20kg of water using our powerful propeller mixer. The resulting slurry is like water, absolutely unusable. Yet on measuring the specific gravity (using a hydrometer because it floats freely) I find that it is too high, I actually have to add more water! How is that even possible? Instead, I add Epsom salts and mix again and the slurry gels and hangs on in a perfectly even layer when I dip the spatula. This is a thixotropic gel, it will apply evenly to bisque ware yet not go on too thickly. We normally recommend a specific gravity of 1.44 for this glaze, but in this case, it seemed watery enough at 1.46 (on use, it will become clear if 1.46 is OK e.g. if it goes onto the ware too thick). If that happens I'll just add water to 1.44 (and more Epson salts if needed). At the time of writing, based on online pricing at this time, coverage is 650-5000% cheaper than buying jars of transparent brushing glaze (I am considering both the total powder weight and the specific gravity difference between this and commercial glazes we use).

Context: G2926B, Thixotropy

Thursday 23rd May 2024

What should the consistency of CMC gum solution be?

Gum solution consistency

This is CMC gum 35g/liter gum solution after it has been thoroughly hot-mixed and cooled to about 30C. As it cools further and sits it thins. Gum solutions can have a higher CMC content, up to double this, but they are more difficult to use.

Most often, gum solution is intended to augment the water when batching a recipe. If added to an already-mixed glaze it thins it - so an equal amount or more water should first be removed. For example, consider converting a dipping glaze to a brushing glaze: Adding 1.5% CMC gum, via gum solution, to a gallon of glaze would also add almost a liter of water (it would become useless and settle out). This being said, a gelling agent like VeeGum can also be added to create a low specific gravity slurry, like many commercial bottled glazes. This enables fine control of thickness since multiple layers must be applied.

Context: CMC Gum, Control gel using Veegum..

Tuesday 21st May 2024

Ravenscrag floating blue color affected by cooling speed

Two floating blue mugs

Ravenscrag Slip really shines in its ability to produce a good floating blue glaze at cone 6, this is the GR6-M recipe. The speed of cooling in the kiln affects the appearance. The mug on the left was cooled faster, using our drop-and-soak PLC6DS firing schedule. The other one was slow-cooled using the C6DHSC schedule. The latter schedule is preferable for these because the G3914A black has a much smoother surface. The blue could be recovered by adding more cobalt.

Context: GR6-M, FLB

Friday 17th May 2024

This amazing difference 45 micron silica can make

A glaze stops crazing with 45 micron silica

The only difference between these two cone 6 glazes is the silica. Both are the G2926B recipe, both were thickly applied and fired in the same kiln. The left one employs the 90 micron (or 200 mesh) grade silica and the right one uses 45 micron (or 325 mesh). These test tiles are about 6 months old. There was no crazing out of the kiln. The porcelain recipe is 25% silica, 25% nepheline and the remainder kaolin and bentonite. It appears the finer particle size silica is dissolving in the melt much better, this narrows the difference between calculated and actual behavior, especially relating to coefficient of thermal expansion. While this grade is better in glazes it is not better in bodies, they most often depend on the thermal expansion increasing effects of the larger particles in the 200 mesh grade.

A reader noted that it is also a matter of the reaction between glaze and body. The original glaze having coarser silica would have smelt and reacted with the body more, the extra dissolution sourcing Na2O - thus increasing the COE of the glaze. Conversely, when the finer silica dissolves it increases melt viscosity thus reducing reaction with the body.

Context: Silica, We thought we were.., The difference between Silica.., Body glaze Interface

Thursday 16th May 2024

An impossible spout is possible by 3D printing

3D printed mold spout

This mold is for a Medalta Potteries ball pitcher having a closed top with a teardrop-shaped spout (lower right). This plaster mould does not need a spare - 3D printing makes it possible to create a pour spout that inserts perfectly into the angled hole. The size of the pour spout reservoir and the degree of insert can tuned so that when the level drops to the bottom it is ready to pour and the hole is perfectly formed.

Context: Pour Spout

Wednesday 15th May 2024

Why are rutile blue glazes susceptible to this blistering problem?

Rutile glaze has blistered

This blistering problem is common in rutile blue glazes, especially high-temperature - this is not saleable. The reason relates to what it takes to create this kind of vibrant variegated aesthetic: Melting the crap out of the glaze and cooling it just right. This particular one is being fired to cone 11 down to get enough melt fluidity to make it crystallize and phase separate. It seems logical that if the glaze is melting so well it should be able to heal any bubbles that form and break (these are more than usual because the body is being overfired and generating gases). However, the fluidity comes with surface tension that can hold the bubbles intact. Each of these holes in the glaze is a product of that - plus another factor: Cooldown is rapid enough that the melt is not sufficiently fluid to heal after bubble breakage. The potter has been using this glaze for many years with success, but a small change in process or materials has occurred to push it past a tipping point. Solutions? A drop and hold firing. Add a flux (e.g. a little lithium or a frit) to make it melt fluid at cone 10R (where the body generates less gasses of decomposition). Replace any high LOI materials in the glaze itself with other materials to source the same oxides.

Context: Rutile Blue Glazes, Glaze Blisters

Tuesday 14th May 2024

Why 3D design and printing is a better way to make slip casting molds

3D printed plaster mold master

I have not made slip casting molds for years because I dread the process, the mess, all the supplies and tools. I am not a mold-making expert either, but I found a way to do it that is fun, rewarding and effective.
-I am wasting less plaster (it is not a green material). And PLA filament is corn starch or sugar cane. And I am not using rubber.
-I spend most time on design, pouring the plaster takes minutes.
-Many fewer tools are needed, the process is less messy.
-No natches make sanding of flat mating faces possible (for better seams than I've ever had).
-No spare is needed, the 3D-printed pour spouts works better.
-More shapes are possible.
-My molds aren't right until at least version 3. 3D makes do-overs or changes in design as easy as a reprint and plaster pour. I can make a mold just to test an idea!

Context: Beer Bottle Master Mold..

Sunday 5th May 2024

Glaze cracks on slip cast ware but not thrown pieces

Glaze going on too thick

Casting clays are much more absorbent, when bisque-fired, than thrown ones, thus the same glaze that goes on the right thickness on a thrown piece can go on twice as thick on a cast one. Here are some measures to take to get it on thinner:
-Bisque higher to reduce porosity.
-Add more water and a gelling agent to create a thixotropic slurry (proceed with caution, at some point it won’t gel).
-Dip more quickly, much more quickly. One way is the use of dipping tongs, this enables dipping and extracting very quickly.
-Prewetting the ware might help on thinner-walled pieces (on thick-walled ones the glaze will still go on too thick).
-Add CMC gum to the glaze, but be careful, that can bring other issues (e.g. drip, drip, drip, drip). Perhaps just enough to create a first coat dipping glaze.

Monday 29th April 2024

How to make a clear dipping glaze work over solid underglazes

Dipping glaze fails to cover underglaze

This is what typically happens when applying a dipping glaze over an underglazed bisque-fired piece - it does not stick. Commercial underglazes impede the absorptive powder of the bisque but it still might be possible to make it work. Here are some options:
- Bisque the under-glazed ware to a low temperature (e.g. cone 010 or lower) and apply dipping glaze to that.
- Make your own underglaze for dipping, leaving out the CMC gum.
- Make your glaze thixotropic - because it is gelled it may hang on in an even layer over the underglaze.
- Make a brushing glaze and paint that over the underglaze. 1%-1.5% CMC gum will make it paintable. 1% additional Veegum will gel it enough that it can tolerate more water and go on thinner, this enables applying multiple coats and gives good control of the final thickness.

Context: Why dipping transparent glazes.., Underglaze

Thursday 25th April 2024

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Greenbarn Potter's Supply Ltd., 9548 - 192nd Street, SURREY, BC V4N 3R9
Phone: 604-888-3411, FAX: 604-888-4247, Email: