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What Causes Smoke Patterns In A Foil Saggar?


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#1 Isculpt

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Posted 29 August 2014 - 01:43 PM

This is probably obvious to everyone but me, but let's say I put a pot into a trashcan with sawdust and wood.  When the sawdust and wood burn, they create smoke which gets on the pot creating color/shadings.  If I wrap the pot in a foil saggar before putting it in the trashcan with the sawdust and wood, how does it get color/shadings?  Doesn't the saggar block the smoke?  I know I'm going to be embarrassed when someone points out something exceedingly obvious in this process that I should already know.....

 

And while we're on the subject, why do people use masking tape to make patterns on a pot that they're going to fire in a trashcan firing instead of using wax to block the smoke and create those patterns?

 

Jayne



#2 Marcia Selsor

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Posted 29 August 2014 - 03:37 PM

Foil sag gars that I do are not fired in a smoky trash can. They are fired with the colorants, chemicals, combustibles inside the foil sealed around the pot. II fire them in a raku kiln.
Russel Fouts uses masking tape resist in his foil sag gars with combustibles sealed in foil. Wax burns off way too early to leave a result of resisting smoke.here is his article on smoke firing in an electric kiln.
http://users.skynet....anPMIJA09lr.pdf

Marcia

#3 Isculpt

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Posted 30 August 2014 - 12:37 PM

What a fantastic article, Marcia!  Instead of the trashcan and all the hassle of building a fire, I'm now planing to use my old kiln that sits on a covered porch.  I was planning to use root kill, copper carbonate and rock salt, but he writes:   "Aluminum foil starts to break up and become flaky between 1200°F (650°C) and1290°F (700°C). This means that most coloring oxides cannot be used because they have little effect below thesetemperatures. In addition, salts can attack the aluminumfoil, breaking it down."  May I ask what your favorite additions are?  So many of the things that are used in traditional western Native American firings are much more readily available in dry climates.  (Dried cow/horse/sheep dung?  Really?  When it rains every darned day here?!)

 

Thank you for sharing the article!  Jayne



#4 Marcia Selsor

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Posted 30 August 2014 - 11:06 PM

Read more of his articles. They cover all types of resists down to lipstick. It is different from ceramic sag gars that are fired in a raku kiln and that uses things like copper carbonate and salt. The ceramic saggars for to 1650. The foil saggars in a raku kiln goes 1250-1400 F.It all depends on what your doing. Cow dung is more for a pit firing with pots going over hot coals, then covered with dried dung until it burns through...about 2-3 hours.

Marcia




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