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cleaning carbon off raku - a problem

updated tue 2 mar 04

 

Simona Drentea on mon 1 mar 04


I have tried a number of things to clean the carbon off raku pieces w/varying
degrees of success. I checked the archives & found all the raves about Bar
Keeper's Friend. Just tried some on a copper matt piece that was light blue.
I did not even rub, just put a bit on a toothbrush & laid it on top of where I
wanted the carbon removed & that beautiful light blue section turned a rust
color immediately. The piece no longer has it's original beauty. It almost
looks like the top layer of glaze just dissolved away & I'm looking at the next
layer.

What happened here? Am I not supposed to use it on copper matte? I noticed
that many of the archives were referring to white crackle. Are you not
supposed to try to get the carbon off copper shiny or matte glazes? I don't mind a
little carbon, but some of my pieces, especially flat tiles have a lot of
carbon. I reduce in newspaper.

Simona in CO

Megan Ratchford on mon 1 mar 04


Simona wrote:
"What happened here? Am I not supposed to use it on copper matte? "

Hi Simona!
I teach raku at the Arvada Center. I recommend never using any type of
scrubbing powder on the matt glazes. Even if there is no color change from
scrubbing, when the piece dries there is usually a white residue from the
scrubbing powder. Try a new green Scotch pad. The ones that are all
scrubby and no sponge. My students who use copper mattes usually take great
care in not dumping their pieces into tons of paper or other reduction
material and just accept what carbon sits on their pieces. With tiles that
gets a bit tricky but can be done. Where are you in Colorado? Can you come
by the Arvada Center? If so, bring some pieces by on Thursday afternoon or
evening and we can talk further...Or email me off list and we can get to the
bottom of this.

Megan Ratchford
Littleton, Colorado
kogi5@earthlink.net

Anne Webb on mon 1 mar 04


hi simona..

i havent tried to take carbon off of matt copper glazes, but have had
success with removing it from gloss copper glazes. We use Comet or a
cleaner called Zud and we use a green scrubby or a soft toothbrush taking
care not to rub too hard, lest you rub off the claze as well.

If you are just looking for carbonization, such as with a white crackle, and
no flashing, letting your pot cool down til its around 1100 F or when there
is still a bit of a glow,before placing it in your reduction material will
make taking carbon off a whole lot more easier. (still not a solution for
your copper matts..sorry)

We use pine shavings from our local cabinet maker or feed store (the type
used for horse stalls) since it doesnt smoke as much as sawdust or newspaper
and yet gives good carbonization.

Anne



>From: Simona Drentea
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: cleaning carbon off raku - a problem
>Date: Mon, 1 Mar 2004 01:52:42 EST
>
>I have tried a number of things to clean the carbon off raku pieces
>w/varying
>degrees of success. I checked the archives & found all the raves about Bar
>Keeper's Friend. Just tried some on a copper matt piece that was light
>blue.
>I did not even rub, just put a bit on a toothbrush & laid it on top of
>where I
>wanted the carbon removed & that beautiful light blue section turned a rust
>color immediately. The piece no longer has it's original beauty. It
>almost
>looks like the top layer of glaze just dissolved away & I'm looking at the
>next
>layer.
>
>What happened here? Am I not supposed to use it on copper matte? I
>noticed
>that many of the archives were referring to white crackle. Are you not
>supposed to try to get the carbon off copper shiny or matte glazes? I
>don't mind a
>little carbon, but some of my pieces, especially flat tiles have a lot of
>carbon. I reduce in newspaper.
>
>Simona in CO

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daniel on mon 1 mar 04


Hi Simona,

Bar Keeper's Friend is great for things like clear crackle. I never touch a
matte glaze with it or lusters for that matter. The glazes are to delicate
it seems. So on mattes I've been told to try to use duct tape. It works to
lift off most of the removal ash and paper - just dab and lift. On copper
lusters (not familiar with others) I basically avoid getting paper on them
by careful lining of the bin with paper so that as little as possible gets
on the piece. This is also very important for terra sig surfaces as they
will not look as good where the paper has touched the surface, at least they
haven't so far.

So stacking a bin. I loosely roll the newspaper (I do not shred it) and
pack the rolls all the way up to the rim of the bin. I use a bin large
enough to put the piece in without touching the paper but not so large as to
give a lot of waste space. I usually put an old piece of kiln shelf in the
bottom of the bin to put the piece on and I fold a piece of paper flat
across that which also touches the rolls of paper in the bottom of the bin.
This aids lighting, though with coppers the pieces are usually hot enough to
catch the paper pretty quickly. It can take a little time to get the paper
to light but fan it a bit and the result can be a beautiful unmarked pot
which you don't really need to clean.

Thanx
D

Laurie Kneppel on mon 1 mar 04


Hi Simona,
I have used cleaners on matte surface raku pieces, but I have always
liked Barkeepers Friend, a green scrubby thing and an old toothbrush
for cleaning the white and other glossy crackle glazes. Got to be
careful on glossy glazes with copper though as it will dull any copper
flashes a bit if you scrub too hard. Also rinse everything very well.
The BKF will leave white residue in the cracks even on glossy glazes if
you don't. On the matte glazed pieces I usually just gently rinse with
soap and plain water and I only scrub the bottoms where they may touch
a table or wall and leave black smudges.

I almost always reduce in leaves since they are very plentiful here in
the City of Trees. My current favorites are liquidambar, but I really
like the smell of burning eucalyptus leaves.

What do people do with raku jewelry? I have always been afraid to try
it since I didn't want customers coming back later and complaining
their pendant (or whatever) got their blouse all black.

Laurie
Sacramento, CA

On Feb 29, 2004, at 10:52 PM, Simona Drentea wrote:

> I have tried a number of things to clean the carbon off raku pieces
> w/varying
> degrees of success. I checked the archives & found all the raves
> about Bar
> Keeper's Friend. Just tried some on a copper matt piece that was
> light blue.
> I did not even rub, just put a bit on a toothbrush & laid it on top of
> where I
> wanted the carbon removed & that beautiful light blue section turned a
> rust
> color immediately.

Phil Smith on mon 1 mar 04


Dear Simona,
I was doing alot of Copper matte last year.
I noticed that when water was applied to the piece for cleaning it turned a
foul looking Gray/green overnight.
I used a chicken wire cylinder to protect piece from combustibles if I
didn't wish to have the charred appearance.
I'm convinced the water is your problem.
If you absolutley have to use it, use very little and dry the piece with
heat gun immediately.

Phil...

Anne Webb on mon 1 mar 04


one other thing, and this may be obvious to some....

to get rid of that white residue when cleaning raku (remember i use comet,
ajax or Zud), ....
after scrubbing with detergent, rinse any residue detergent off the pot
well.
then, while keeping water running over the pot, use a soft toothbrush and
brush *gently* using small circular motion over the areas affected. rinse
well. if you see more residue once pot dries, try brushing some more over
the areas u missed. usually works like a charm for me.


>From: Megan Ratchford
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: cleaning carbon off raku - a problem
>Date: Mon, 1 Mar 2004 06:29:23 -0700
>
>Simona wrote:
> "What happened here? Am I not supposed to use it on copper matte? "
>
>Hi Simona!
> I teach raku at the Arvada Center. I recommend never using any type
>of
>scrubbing powder on the matt glazes. Even if there is no color change from
>scrubbing, when the piece dries there is usually a white residue from the
>scrubbing powder. Try a new green Scotch pad. The ones that are all
>scrubby and no sponge. My students who use copper mattes usually take
>great
>care in not dumping their pieces into tons of paper or other reduction
>material and just accept what carbon sits on their pieces. With tiles that
>gets a bit tricky but can be done. Where are you in Colorado? Can you
>come
>by the Arvada Center? If so, bring some pieces by on Thursday afternoon or
>evening and we can talk further...Or email me off list and we can get to
>the
>bottom of this.
>
>Megan Ratchford
>Littleton, Colorado
>kogi5@earthlink.net
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.

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Kim Peterson on mon 1 mar 04


Simona,
I also use the green scrubby tha Megan recommended.. The amount of water
dowsn't cause a problem for me.. You might have a higher concentration of
chlorine?? Do not use a bleaching agent like ajax on coppers. Turns it a
tourq. green, similar to a 57 caddie from AZ. that's never seen a wax job..
I have use a cleanser on my matt finishes, but I'd rather not..
Sometimes I'll get a bit of creosote on a pieces.. Often comes off with dish
soap..
Take Megan up on her offer to visit.. I'm sure you'll enjoy yourself!
Kim Peterson


>From: Phil Smith
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: cleaning carbon off raku - a problem
>Date: Mon, 1 Mar 2004 14:07:18 -0500
>
>Dear Simona,
>I was doing alot of Copper matte last year.
>I noticed that when water was applied to the piece for cleaning it turned a
>foul looking Gray/green overnight.
>I used a chicken wire cylinder to protect piece from combustibles if I
>didn't wish to have the charred appearance.
>I'm convinced the water is your problem.
>If you absolutley have to use it, use very little and dry the piece with
>heat gun immediately.
>
>Phil...
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.

_________________________________________________________________
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