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Yikes! Glaze Removal ?


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#1 PetrosV

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Posted 24 April 2011 - 04:17 PM

Hi,

I want to take an old tile and get the glaze off of it or as much of it as possible. I have no prior ceramic experience. (your laughing right?) I assume it is not possible but I was reading
about some mistake a low fire glaze put in a high temp shelf and the glaze ran off. So can I put a majolica tile (100 years old?) into a kiln and tilt it in some pan to catch glaze and expect at least some of the glaze to run off?

Having no idea what cone it was fired at (I assume cone is temp) what will happen if it goes into the hottest kiln possible, could the tile crack ?


I also wonder is there any chemical process that would eat the glaze without eating the tile. It's glass right?

How about taking a torch to the tile surface? (probably not hot enough unless it's something for 4" steel right?)


Thanks for any info you can provide - probably the least discussed topic in all ceramic arts right?

#2 Chris Campbell

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Posted 24 April 2011 - 06:12 PM

Well, your questions certainly woke us all up!

If you put the tile into a high firing kiln you will probably melt the tile along with the glaze.
Not all clays are meant to be fired that high.

My question to you ... Why?
Why are you trying to do this ... Do you like the tile but dislike the glaze?
Maybe there is an easier way to reach your goal.

Chris Campbell
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#3 Firemountaion Studios

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Posted 24 April 2011 - 06:52 PM

Do not try to remove the glaze, there is no way this would turn out well.

Three options I can think of:

#1. Try over glazing it (talk to a potter with experience over glazing and get their help).

#2. Make a plaster cast or press mold of the tile, and make a new one.

#3. Find the maker of the tile and go on line and and see if they make one you like, or if there any on e-bay for sale.

#4 PetrosV

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Posted 24 April 2011 - 07:39 PM

Well, your questions certainly woke us all up!

If you put the tile into a high firing kiln you will probably melt the tile along with the glaze.
Not all clays are meant to be fired that high.

My question to you ... Why?
Why are you trying to do this ... Do you like the tile but dislike the glaze?
Maybe there is an easier way to reach your goal.


thanks for the info. It is a relief tile and I want to make it look different. The glaze is welled up in the recesses and I'd like to just have a plain tile and do another look altogether with the color

I just wonder if there is a chemical that will eat the glaze (like etch solution can dissolve glass right?) but not damage the clay?

#5 AmeriSwede

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Posted 25 April 2011 - 12:23 AM

I just wonder if there is a chemical that will eat the glaze (like etch solution can dissolve glass right?) but not damage the clay?





Posted Image OUCH Posted Image

Yes there probably is a chemical... one of the strongest, most dangerous to handle acids that a craftsman could ever even consider using, called hydrofluoric acid. It can eat away glasses and human tissue, interior and exterior! The expense of the NECESSARY and PROPER safety clothing, equipment and highly exhausted work area is far greater than what your end goal would achieve. This is certainly not to be taken lightly. And yes, I have 5 years experience in working with HF on glass. Even with the appropriate knowledge, safety equipment, professional site and skills in handling the vile stuff, there always remained an incredible respect and FEAR of the acid, in my mind!

ABSOLUTELY and DEFINITELY READ THE INFORMATION LINK in its entirety (GOOGLE and read everything about its horrors also) and then disregard the attempt to eliminate the glaze on your tile, altogether. Then follow the advice already posted! If it is an antique majolica tile as you mention in your original posting then chances are high that attempting to melt or burn off the glaze at a higher temperature would in fact damage the tile itself, or kiln shelves, which would be contrary to your objective. Using an acid to dissolve the glaze off is even greater in its hazards as the damage is to YOUR body, forever.

My suggestion is to actually model a new tile in clay from the original or have someone with this skill if you lack the modeling skill yourself! You will end up with a crisper defined relief for firing or for making a mold. A mold made from a new modeled tile is certainly the best idea, as you have the opportunity to try various other glaze (color) combinations on numerous tiles then. After all, who's to say that if you were actually able to eliminate the glaze from the original tile, that your new glaze would be as good or better?

Chris' query above, '...Why?' amplifies my own question of 'Why' .... when it could be easier to remodel.

----rick


------Rick



Above all, it is a matter of loving art, not understanding it. (Fernand Leger
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#6 Guest_HerbNorris_*

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Posted 25 April 2011 - 12:56 AM

HF will dissolve your tile as well. HF is sometimes used to make removal of fossils from silicate rocks easier, and used to help isolate minerals from them as well.
It will certainly dissolve any kaolin or kaolinite that might be in the tile.
I have had to test HF for quality purposes in a pharma/lab setting.
Ameriswede is right, this is not a chemical to be used casually, should you be able to get some.

#7 Chris Campbell

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Posted 25 April 2011 - 02:44 PM

The best course would be to cast a mold of the tile ...
Then make a tile from the mold that will serve as a working model.
Use this one to refine the pattern and get the tile looking just like you want it.
Then cast another mold of this one.
Now you have a master mold that you can use to make as many as you want.
Instead of being dangerous, it will be a lot of fun and a great learning experience for you.

Chris Campbell
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#8 Marcia Selsor

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Posted 26 April 2011 - 09:56 AM

You can sandblast the glaze off the tile. You could locate a machine shop with a sandblaster.
That is the best solution I can think of.
Marcia

#9 azjoe

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Posted 26 April 2011 - 12:31 PM

You can sandblast the glaze off the tile. You could locate a machine shop with a sandblaster.
That is the best solution I can think of.
Marcia


I agree with Marcia that sandblasting is probably the best approach... HOWEVER, you said "The glaze is welled up in the recesses...". I think care must be taken when sandblasting if you want to maintain as much of the relief detail, particularly in those recesses (where the glaze is thicker and/or has pooled) since the glaze is probably harder than the vitreous fired clay under the glaze. You won't know until you try it... just in case I'd make a plaster cast of the tile before you sandblast. Make sure the place you have it blasted has the proper equipment... eg, a micro sandblaster (as opposed to equipment used to strip paint from cars and remove rust from large metal pieces)... ie, something like this... Micronblaster . Depending on the size of the tile this could be a long tedious process.




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