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Member Since 16 Mar 2013
Offline Last Active Feb 19 2014 09:44 AM

Topics I've Started

Diy Kiln Vent

31 December 2013 - 04:26 PM

I just want to share a few photos of my kiln vent project.


The pin and its bushing were machined out of mild steel. The round foot - aluminum.

I didn't machine the circular top collar: I just found it in my scrap bin and used "as is" (the holes drilled in the collar do not interfere with its function, so I just left them alone).


I used the vent during several firings, then sandblasted the newly formed rust away and painted everything to finish the project. The pin was not painted. I blackened it to protect against rusting (it was heated, and used machine oil was rubbed into the surface). It looks like rust on the photos, but it's not. The inside of the bushing should be done the same way.


As you can see, magnets are used to regulate fresh air intake.


P.S. If I ever make one again, I'll use aluminum or stainless steel for everything (except the connection to the galvanized exhaust). Naturally, I'll have to make some kind of shutters instead of magnets then. This would require no painting and won't rust.

Sodium Silicate Crackle Pattern Problem

30 December 2013 - 09:28 AM

I recently made a batch of pottery using Sodium silicate to get crackled surface. Everything went extremely well.


A couple of days ago I decided to make another batch. I throw a piece, dry the porcelain surface a little with propane flame, apply sodium silicate or its mix with a slip, dry the layer with a heat gun and start stretching.


This time I only get vertical cracks that quite quickly become a way too deep. No fine cross pattern (spider web) at all. Same porcelain fresh from the box, same sodium silicate and SS/slip mix as before.


I tried thin and thick Sodium silicate layers, flamed and raw porcelain surfaces. The results are still exactly the same.


What I didn't try yet is leaving the SS crust a bit more moist. Also, this time I throw mugs, so I leave the porcelain walls thinner since I'm not going to expand them much. But even if I wanted, I couldn't expand them more because of the deep vertical cracks that rip the surface apart as soon as I overstretch it a bit.


While I was struggling with porcelain, my wife made a few hand built pieces out of stoneware, and didn't have this problem.


What do you think can be the cause?


Thank you.



What Midrange Porcelain Do You Prefer?

21 October 2013 - 11:12 AM

What porcelain for Cone 4-6 firing in electric kilns do you prefer (brand, #)? Do you buy it locally or by mail? What does it cost to you in the end (and in what quantity)?


Did anybody try P-5 porcelain sold by Clay King?


What cone do you fire yours to for functional pottery? I mean if it's Cone 5-6, do you prefer to fire it to ^5 or to ^6?





Is this a Sugar Creek spray booth? Drainage ideas wanted.

06 June 2013 - 06:15 PM

I've got a booth that I suspect was made by Sugar Creek (see photos below). Sugar Creek is out of business. If you think it was made by a different manufacturer, I'd be happy to find out its name.

The opening of the booth is 40" wide x 29 1/2" high. There is a fan installed in a 12" dia. exhaust. The booth uses regular furnace filters (removed before taking photos).

If this is what you have, does the paperwork mention the fan rating (CFM)? Also I wonder what the manufacturer has suggested in terms of drainage. What was YOUR approach to it, and how do you like the result?

As you can see, the bottom is flat. I have a few ideas ranging from using old newspapers to collect the moisture to drilling a hole in a back corner and slightly tilting the booth so that water flows toward the drain. A properly shaped secondary floor with a drain is something else that comes to my mind. Rails directing water toward a drain location is yet another idea (the easiest would be to have it drained over the front edge, but it sounds almost as ugly of a design as using newspapers).

Any ideas are welcome.

Thank you.


PID Controller Programming. Cone 05 Bisque and Cone 5-6 Glaze Firing Schedules

03 June 2013 - 09:38 PM

I'd like to post my notes on programming a simple Ramp and Soak PID temperature controller for Bisque (Cone 05) and Glaze (Cone 5-6) Firing. The Glaze Firing Schedule was adopted from the book "Mastering Cone 6 Glazes" by John Hesselberth and Ron Roy. The Bisque Firing Schedule is based on suggestions found in many books and other sources of information.

Note that the controller is programmed in Celsius. The controller operates an SSR (Solid State Relay) which switches the kiln on and off (Note: if you use a mechanical or mercury relay, use Cycle Time value from 20 to 40 instead of "5" in the PID setup).

My controller is capable of programming 50 steps. I allocated steps 1 through 7 for Bisque Firing program and steps 15 through 21 for Glaze firing.

I hope someone may find these notes helpful for setting and programming his/her own PID controller.It'll be quite easy to substitute the temperature and time values if you want to change the curves.