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Naked Raku Troubleshooting


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#1 AWPottery

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Posted 01 March 2014 - 09:56 PM

First off... thanks to everyone who has been helping me with all these naked raku questions I have been posting.

 

Okay, so a few days ago we did our first naked raku firing....

My results posed these questions so far

 

1) On pots that I used white terra sig I noticed that they turned more of a gray and black instead of a white and black?  Anyone have any suggestions on why this is?  My thoughts were maybe because instead of using porcelain clay I used stoneware?  Or perhaps I put to much newspaper in the trashcan when reducing?

 

2) I also did some pots with red terra sig and we fired one of them.  Afterwards when I was cleaning it off, it completely wiped off the black crackle lines, basically just leaving me with the original pot of red terra sig.  What could have caused this?  Again this pot was stoneware, but I also fired this piece to cone 04 instead of 09 unlike the others.  Or could it have something to do with the color? Thoughts?  B/c if possible I would like to try firing it again if it could work.

 



#2 Marcia Selsor

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Posted 02 March 2014 - 08:31 AM

what temperature was your bisque firing?

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#3 AWPottery

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Posted 02 March 2014 - 09:13 AM

Marcia....

 

for the first pot to question one which was terra sig'd white I bisque the pot to 09 like you suggested

 

for the second pot to question two it was bisque to 04 (the red terra sig'd one) b/c it was done b/4 I knew it was better to fire the terra sig'd pieces to a lower temp



#4 AWPottery

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Posted 02 March 2014 - 09:15 AM

Or did you mean what temp was the naked raku firing?  B/c we fired that to 1500 degrees



#5 AWPottery

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Posted 02 March 2014 - 06:44 PM

Anyone? Ideas?



#6 ayjay

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Posted 03 March 2014 - 06:01 AM

Anyone? Ideas?

I can't help much, but I doubt it's too much newspaper: when I've done it  they go into a dustbin full of sawdust and shavings and get covered with more of the same before a lid goes on for about 20 minutes.



#7 Marcia Selsor

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Posted 03 March 2014 - 09:10 AM

#2Bisque firing temperature. I wondered if the bisque was high for the terra sig. So the red sig may have sealed at 04 and not accepted the carbon.
#1reading Linda and Charlie Rigg's directions, their fire their naked raku to 1450.
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#8 PeterH

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Posted 03 March 2014 - 09:22 AM

AWPottery,

 

Are you using one or two part slip?

 

1) On pots that I used white terra sig I noticed that they turned more of a gray and black instead of a white and black?  Anyone have any suggestions on why this is?  My thoughts were maybe because instead of using porcelain clay I used stoneware?  Or perhaps I put to much newspaper in the trashcan when reducing?

 

In my experience the grey happens when the refractory coat of a 2-part slip is too thin or porous (or the glaze not fully melting).

Or the slip might be starting to peel off, so the smoke is getting under it.

 

2) I also did some pots with red terra sig and we fired one of them.  Afterwards when I was cleaning it off, it completely wiped off the black crackle lines, basically just leaving me with the original pot of red terra sig.  What could have caused this?  Again this pot was stoneware, but I also fired this piece to cone 04 instead of 09 unlike the others.  Or could it have something to do with the color? Thoughts?  B/c if possible I would like to try firing it again if it could work.

 

I would fire again without any slip. If the black still wipes off, then the pot or t-sig is insufficiently porous to accept smoke (if the

foot of the pot has no t-sig, you can see how the body reacted). Even if you cannot use the pot for naked raku, you can still refire

with glazes. If you do get a good black, you can reslip and try for naked raku again (putting the first failure down to innapropriate

temperatures?).

 

Regards, Peter

 

 



#9 AWPottery

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Posted 03 March 2014 - 10:03 AM

Peter,

 

1)  This was a 2 part slip.  It was put on fairly thick.  However,, a few pieces did peel off so perhaps that could be it.

2)   On this pot (the red t-sig) it is interesting what you suggested because I did put red t-sig on the body of the pot but left a small top portion w/out t-sig and it did accept the smoke so the rim of the pot is black, but on the body of the pot where it was t-sig the smoke completely came off.



#10 PeterH

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Posted 03 March 2014 - 04:25 PM

AWPottery,

 

1)  This was a 2 part slip.  It was put on fairly thick.  However,, a few pieces did peel off so perhaps that could be it.

 

For a 2-part slip the main purpose of the 1st layer is to stop the 2nd (glaze) layer sticking to the pot, so it doesn’t need to be too thick.

A bit of food colouring in the 1st layer helps to make sure that you get full coverage coats of both layers over the entire pot.

 

I think I've had grey "whites" with very thin pots (the smoke going though the pot from the inside). However unless you cast your pieces

they are unlikely to be this thin, if they are, glaze them internally.

 

2)   On this pot (the red t-sig) it is interesting what you suggested because I did put red t-sig on the body of the pot but left a small top portion w/out t-sig and it did accept the smoke so the rim of the pot is black, but on the body of the pot where it was t-sig the smoke completely came off.

 

That does sound like you overfired your t-sig.

 

Regards, Peter

 

PS You can mix naked and glazed raku on the same pot if you separate the different areas with a thin line of copydex

(a thick-ish latex glue), this leaves you with a blackish line between the regions. Remember to peel off the glue before

firing. Even just naked rake + plain crackle (same glaze) looks surprisingly good. Copydex is the only way I've found to

avoid trouble with the 2nd glaze layer of the naked rake touching the pot at the edge, and sticking permanently.



#11 Marcia Selsor

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Posted 03 March 2014 - 04:39 PM

That is what I thought too.The terra sig sealed at 04 bisque.


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#12 AWPottery

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Posted 03 March 2014 - 05:07 PM

Peter, thanks for answering my questions :)  Cool tidbit about doing naked raku and regular raku together!

 

Marcia, thanks for answering me as well.  You've always been helpful. 



#13 PeterH

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Posted 03 March 2014 - 07:26 PM

AWPottery.

 

Copydex is the only way I've found to avoid trouble with the 2nd glaze layer of the naked rake touching the pot at the edge, and sticking permanently.

 

Must try to engage mind before typing. I've tried things like wax resist and they didn't work. You can of course use masking tape and peel before firing.

Depends if you want straight edges or a less formal effect. I've always had problems trying to get thin lines with masking tape.

 

Regards, Peter



#14 AWPottery

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Posted 04 March 2014 - 07:39 AM

Peter- you mentioned doing naked raku and regular raku on the same pot.   I like this idea, but what temp are you firing these pieces then?  B/c were I take the classes they are firing the naked raku at 1500 and the raku pieces at 1800.  How would this work?



#15 Marcia Selsor

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Posted 04 March 2014 - 07:52 AM

I use latex for peeling away images in Raku.
I thin it a little.
Do some more reading. David Roberts, Wally Asselbergh, Linda and Charlie Riggs, are among my favorite at this technique.
http://www.mudfire.c...op-20101023.htm

David Roberts large piece are sanded with a diamond pad and have a wonderful feel to the surface.

Marcia

#16 PeterH

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Posted 04 March 2014 - 11:57 AM

AWPottery,

 

Peter- you mentioned doing naked raku and regular raku on the same pot.   I like this idea, but what temp are you firing these pieces then?  B/c were I take the classes they are firing the naked raku at 1500 and the raku pieces at 1800.  How would this work?

 

At the raku firings I go to they fire everything at about 1030C. So I have to formulate things for this temperature.

 

Do you have 1800F glazes available to you (including a crackle)? Do you mix any of your own?

 

Do you mix your own bottom-slip for the 2-part raku?

 

Regards, Peter






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