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Bob Coyle

Member Since 06 Jun 2013
Offline Last Active May 21 2016 08:14 PM

#107274 Lose The Sitter Your Opinion Counts

Posted by Bob Coyle on 21 May 2016 - 08:11 PM

Leave the sitter. Digital controllers can fail, but gravity does not. Put a cone higher than you will reach in the sitter. It's there already, so why not have one more layer of fail safe.

#107236 Newbie Needs Help With Glaze Cone 6 - Can It Really Be This Hard?

Posted by Bob Coyle on 20 May 2016 - 06:11 PM

Cheat and throw in 0.5% cobalt carb.

#106547 Does Anyone Know How To Achieve Similar Results To This?

Posted by Bob Coyle on 08 May 2016 - 06:22 PM

It's simple... terra sig ... and ten years of practice.


Good luck Muddy

#103330 How To Increase Crackle Effect In Raku

Posted by Bob Coyle on 09 March 2016 - 07:28 PM

A lot has to do with the glaze and clay body. We are talking forced shrinkage here. I have found that thicker pieces sometimes crackle better than thin, but I have not a lot of experience in this.

#103001 New Blue Pigment

Posted by Bob Coyle on 02 March 2016 - 08:58 PM

“YInMn” blue... Humm ? Yttrium,Indium, manganese  here is the link to what they did http://colmat.icmse..../P27_DP2011.pdf


I agree with Niel, probably would be unstable in a melt. The pigment itself is created at 1100C, so you might be able to pull off a low fire, but it still would probably react with the flux and change color..  The glazes they made don't seem to be that impressive.

#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.