Slip to Plastic Clay - De-Watering with Vacuum Bag

The following video clips illustrate my vacuum bag process for removing excess water from my slip mixed clay body tests. This is a reasonably simple approach to achieve maximum plasticity for a clay body test, without the need for maturing the clay over a long period of time.  Using this method a small shop clay worker can easily go from wet slip to fully plastic clay in a single week. Hand mixing clay tests without the slip wetting step will not produce a body test with anywhere near its full plastic potential. If clay tests are not fully wetted the results can be so misleading as to clay working properties and be a total waste of time to prepare.

Part 1: Mixing clay slip for vacuum de-watering

The inspiration for my method came directly from The Potter's Alternative by Harry Davis who as far as I am concerned was a mechanical genius potter. The vacuum de-watering solution described in this book was limited by then available tools and materials and so perhaps anachronistic today. Nevertheless—his basic assumptions were innovative and sound and I offer my enthusiastic recommendation for his now out of print book which is occasionally available used on Amazon. I also heavily referenced Harry's book when I designed and built my double auger pug mill which I will describe in future posts.

 Part 2: Removing excess water from the slip clay.

 My vacuum water removal method does require a few exotic bits & pieces but the overall cost is not prohibitive for anyone who seriously wants to formulate & test mix their own clay body recipes. My vacuum bag was supplied by Vacuum Bagging Systems in Brunswick, ME. The owner Darryl Keil has clay working experience to support his recommendations for the required parts (including small vacuum pumps). Darryl's business supplies vacuum bagging equipment to custom wood workers as the preferred method for clamping 3 dimensionally curved veneers.

Any vacuum bag supplier servicing the wood working industry can supply the required bags and parts. The single open ended filter bag used in my system was supplied by Crosible—the same company that supplies filter cloths for my Netzsch filter press.  My system draws its vacuum from my pug mill vacuum pump eliminating the need for a separate dedicated pump.

Part 3: Vacuum bag de-watering to produce plastic clay

Turning slipped clay into plastic clay has long been preferred method. This approach removes excess mixing water quickly but does add the expense of purchasing and configuring the required parts.  I certainly believe the traditional approach is simpler and has the added benefit of exercising one's patience (well worth developing).

Mr Issac Button, the last great English country potter, used traditional methods in his pottery—including de-watering slip to make plastic clay. My post illustrating the virtue of Mr Button's time tested method, is inspirational and a must see.

Bentone EW - Glaze Suspender

In the process of trouble shooting recent crystalline glaze spraying problems I found and carefully read posts by John Tilton regarding his experience using Bentone EW. Concluding it must be finer 'n frog's hair I thought I would give a try—until I found none of our suppliers stocked or had even heard of it.

A prolonged Google search revealed Elementis as the source of Bentone EW which in New England is distributed by TMC Materials INC. At $6.52 per lb I briefly thought my supply problem solved until I learned of their 50 lb minimum. Since they were not able to suggest a small quantity supplier I briefly considered selling small lots of the 50 lb bag on our eBay store. Fortunately my continued search identified Dallas based Trinity Ceramic Supply as stocking and selling small quantities of this elusive powder. A quick call confirmed a 1 lb order @ $10.50 + shipping. As far as I can determine (my determination is definitely fallable) Trinity is the only domestic company supplying small quantities of Bentone EW?

Bentone EW — Supreme Suspender ?

For the technically inclined— DigitalFire publishes the following analysis as well as a detailed description of the product which is probably not derived from actual use.

C.E.C.: 78 me/100 gm
Principle Exchange Ion: Na
pH (5% solids slurry): 8.5
Hectorite Content: 90%
Minus 50 mesh: 90%
Minus 325 mesh: 99.5%
Surface Area: 600 sq. meter/gram
Bulk Density (not compacted): 0.24-0.37 g/cc

Perhaps this supplier information will assist those wishing to purchase and test the use of Bentone EW.

Sink Making Process: Series Three

                                 Part 7: Artisan Style Bath Sink Construction

Hand formed bath sink overflow addition  is demonstrated.

 

                                                        

                                       Part 8: with hand Formed overflow

The hand forming of a bathroom sink overflow tunnel is demonstrated.

                                                                         

Part 9: Hand Formed Overflow On Porcelain Sink

The process of hand forming an overflow on a 18 inch OD rimmed style sink which will shrink to 16 inch OD after glaze firing.

Sink Making Process: Series Two

                                     Part 4: with style changes and reduced size

Traditional wheel throwing techniques are used to reduce the diameter and change the rim style of a pressed sink form.

                               

                   Part 5: Small Vessel Sink Styled and Sized with Custom Detail

Ram pressed porcelain basin is hand formed and altered to re-size as a small bathroom vessel.

                                                                   

                              Part 6: Pressing and Drain Overflow Addition

Bath sink is hand altered on foam forms with traditional wheel techniques to re-size and re-style the custom basin.

                                                                      

                          

Sink Making Process: Series One

This series of videos provide a detailed description of each step in the process of making my Water Stone line of bath sinks at Maine Kiln Works. The videos provide a detailed insight into the tools and processes, both traditional and contemporary, which are used to create the Artisan styled sinks.  In 2001. After 30 years of hand throwing bath sinks—I added a 60 ton Ram Press and began press forming sink blanks which are then individually finished by hand. This post-forming alteration process allows 3 sink styles and 3 sink sizes to be finished from a single resin die made to press an 18 inch OD overflow sink blank.

                              
                                   Part 1: Ram Press Formed Sink Process

Maine Kiln Works uses the Ram Press Process in an unusual way which leverages both modern industrial and traditional clay forming techniques. The press produces sink cross sections which are much denser than hand thrown sinks—reduces drying & firing distortion, limits shrinkage while producing a more durable high quality bath appliance.

                                                 

                                           Part 2: Hand Detailed Bath Sink

Press forming and hand finishing demonstration & description—three different styles and sizes of custom detailed bathroom sinks.

                                                                          

                             Part 3: Rimmed Porcelain with Custom Detail

Contemporary bathroom vessel style sink—altered with hand detailing and custom sizing.