Jump to content

Bob Coyle

Member Since 06 Jun 2013
Offline Last Active Today, 01:16 PM

#100566 Stop Me Before I Ruin It Please

Posted by Bob Coyle on 24 January 2016 - 06:18 PM

Like Tyler says.... FIRE A TEST TILE! In fact fire many with different glaze/underglaze overlaps

#99827 Design Trends 2016

Posted by Bob Coyle on 15 January 2016 - 09:21 PM

Interesting Miss B... I have no doubt that the 3-D print fad will effect ceramics. It is no stretch at all from using molten plastic to thick slip to build a piece. Then the question arises... is it art or technology. In my mind it is technology, although you may use a graphics development environment to program what is made. I am pretty retro. I think that it doesn't count as art unless you are creating it directly with your hands. Of course , this would also rule out photography as a fine art media, and I have no problem with that.  I hope expressing my opinion doesn't get me flamed again, but this is ONLY my opinion.

#99529 Home Made Kiln Controller

Posted by Bob Coyle on 13 January 2016 - 05:50 PM

screen dumps of the user interface ...Attached File  chart.jpg   166.2KB   0 downloadsAttached File  ramp.jpg   93.28KB   0 downloads

#97982 My Journey In 2015 - A Big Thanks To This Community.

Posted by Bob Coyle on 25 December 2015 - 12:47 PM

Throwing like a pro Joseph. I like how you experiment with your forms. Looks like great fun.


Onward to 2016!

#97797 Glaze Test City

Posted by Bob Coyle on 22 December 2015 - 10:27 PM

Rate laws!... Gibs free energy!... I'm back in P-Chem!


Seriously though, trying to predict glaze behavior by more or less first principals is in my opinion, like using thermodynamics to predict the weather.  The complexity of more than a dozen different chemical entity's interacting in a molten solution would require some real hairy computation for even coming close to predicting anything.


This ground has already been plowed by geologists trying to understand rock formation and by scientists trying to develop better glass products.. both of which glazes are. I myself have downloaded many articles on these subjects and realize that the math of predicting behavior of even three or four component systems requires writing a complex computer program to crunch the permutations of possible chemical interactions that may take place.


I think Tyler summed up most of the research that has been done on multi-component glasses. the researchers found ....


The glaze itself is all a covalent lattice--ish (structure.)


Before anyone says a word more, I highly recommend they sit through this lecture on glass given at MIT. It is the clearest and best first principle-ish explanation I have run into... happy watching! :)    https://www.youtube....h?v=kB2Ue4Fip2c

#97136 Bismuth Nitrate Or Subnitrate

Posted by Bob Coyle on 10 December 2015 - 04:52 PM

Bi atomic weight is 209

that means the ratio of Bi to Bismuth Nitrate is 209/485  or about 43% by weight


and for Bismuth Subnitrate (209 x 5) /1462 or about 72% by weight


So the Bismuth Subnitrate is a better buy.

#95913 Horse Hair Firing

Posted by Bob Coyle on 16 November 2015 - 11:07 AM

Benzine is correct. Vitrified pots would probably crack, and even if they did not, the horse hair would not make the distinctive smokey trace. 


As I mentioned before, I have reheated bisque fired pots with a propane torch and then placed horse hair on the heated surface and it worked. You have to heat the surfaces slowly and bring them up to a high enough temperature to carbonize the hair. Hold the hair in both hands and loosely drape it over the hot surface.It takes some practice, but I have done lots of them this way.

#95210 Combining Handbuilt And Wheel

Posted by Bob Coyle on 03 November 2015 - 01:58 PM

I have seen plans and you-tube videos on centering jigs that you can build or buy. You might check out on the web. There are lots of potters with physical issues that have devised a work around.

#94642 The Dreamer And The Cynic

Posted by Bob Coyle on 22 October 2015 - 10:07 AM

I found this picture taken by a friend. It looks like an art installation somewhere. I don't know where she saw it but I thought others might like it.



Attached Files

#93909 Horse Hair Firing

Posted by Bob Coyle on 07 October 2015 - 07:29 PM

I have bisqued low fire clay and then used a propane torch to heat the pot to a temperature high enough to do a horse hair firing. If you pull the pot out of a low fire you need to let it cool down to the point where the horse hair will burn and leave a carbon trace. If it is too hot, the carbon will burn away. Too cool, and the hair wont burn to the surface of the pot.  There is a learning curve, not only on temperature, but also how you apply the horse hair. ( go to u-tube!!!)


As I said, I did horse hair fires with cold pots heated up with a propane torch. If the effect didn't look right, I just kept heating till the carbon trace burned off, and tried again. Horse hair firing is an art in itself. It ain't rocket science , but it isn't slam dunk either.


If you want to try it out of the kiln, then go for it. If you have a kiln controller, set it to where you see a low red heat. Pull the pot out, and when it loses the glow, start putting your hair on it till you get good traces. To erase mistakes, put it back in the kiln.

#92440 My Custom Made Bead Racks Actually Worked!

Posted by Bob Coyle on 11 September 2015 - 06:41 PM

Amazing what you can do with clay!  The more you know, the less you need to buy.

#91626 Can I Tumblestack Underglaze Greenware For The Bisque Fire?

Posted by Bob Coyle on 28 August 2015 - 06:50 PM

You SHOULD be able to bisque un-glazed greenware stacked. Under glazes is a different problem. If you fire below the flux temp of the under-glaze you probably OK. Err on the side of safety. and wipe the bottoms and don't stack them if you are not sure. Maybe stack one or two and try it.


If you are new to this, slow down and learn what will work and not work by testing non-critical pieces.

#90802 Making Pottery Or Metalsmithing

Posted by Bob Coyle on 13 August 2015 - 03:28 PM


whatever u guys do, do not mix glass and pottery

Yes, the COE is way off. the glass will crack if is fuses to the clay. I would still like to have a try at it with for a purely sculptural piece


In theory,  you might pull it off by creating a glazed ceramic piece as sort of a frame. The inside part of the frame would be left unglazed and have a undercut in the center


kind of like    {--------- glass -----------}  


The inside edge is then painted with non sticking kiln wash and dried. Seems like if you cut a thick piece of glass to just fit and then fired the whole thing at slump temperature the glass might flow into the frame and just form a mechanical fit rather than fuse. Then after annealing it and cooling it, you could clean off the kiln wash and the glass would stay in place.


As Stephen said though, you would definitely not want to do this where people might doing anything other than looking at it.

#90413 Home Made Kiln Controller

Posted by Bob Coyle on 07 August 2015 - 06:22 PM



The above is a link to the Arduino MAX31855 library . Why re-invent the wheel. I have been using the Arduino to control my kiln for several years.


Here is the code I use.


#include <MAX31855.h>

float tempOut = 0;
int command = 0;
int value;
// Adruino 1.0 pre-defines these variables
//int SCk = 13;
//int MISO = 12;//SO
//int SS = 11;//CS

// Setup the variables we are going to use.
double tempTC, tempCJC;
bool faultOpen, faultShortGND, faultShortVCC, x;
bool temp_unit = 0; // 0 = Celsius, 1 = Fahrenheit
MAX31855 temp(11, 12, 13);

void setup() {
  pinMode(2, OUTPUT);      // Test Com Reset issue  
  pinMode(3, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode (10,OUTPUT);
  digitalWrite(10, HIGH);



void Average10() { // average 10 readings
  float Ave;
  int AveCt ;
  AveCt =0;
  Ave = 0;
  do {
      temp.readMAX31855(&tempTC, &tempCJC, &faultOpen, &faultShortGND, &faultShortVCC, temp_unit);
      Ave = Ave +  tempTC ; // tempTC ;
      AveCt = AveCt + 1;
     } while  (AveCt < 10 ) ;
    tempOut = (Ave/10);

void loop() {
   if ( analogRead(0)> 1021) {          // it's too high turn it off
     value = 0;
     if (Serial.available()) {      // Look for char in serial que and process if found
      command = Serial.read();
      if (command == 84 ) { // If command = "T" turn it on (unless to high)
         // delay (500); // keep it on for at least half a sec to prevent bounce
      if (command == 67) {          // If command = "C" turn it off
         // delay(500); // keep it off for at least half a second to prevent bounce
      if (command==68){                 //if command ="D" sound tone
      if (command==69){                 //if command ="E" end tone
          command = 0;                 // reset command
    Average10(); // take averaged sample
    Serial.print("@- ");
    Serial.print(tempOut);       // output to computer USB port
    Serial.println(" -Tmp ");


I use a Visual basic or a Java software  interface to do the logic to control the kiln. You can use any code that allows you to read/write from a usb device. 

A solid state relay is used to toggle the kiln on and off directly from the Arduino.


I use an AD595 chip rather then the MAX because Of noise problems. The AD595 is a very stable A/D for type K thermocouples. It works pretty much the same except you have to run it through a op amp.


Do some research on Google... there is a lot out there already done for you.



#90353 Making Pottery Or Metalsmithing

Posted by Bob Coyle on 06 August 2015 - 11:50 AM

I have been doing mixed media ( clay/metal/wood) pieces and they have gotten a good reception. People really like the the concept of blacksmithed metal bases on ceramic vessels.


I have really gotten big lately with an eight foot anthropomorphic clay and metal outdoor sculpture..


There are not a lot of people out there doing this type of thing, so it gives you a pretty good market nich, if you can combine both.

Attached Files