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My Standard ceramic Seamist glaze was going on too thick, even though the specific gravity was measuring ok. It was not settling out in the bucket at all upon standing. On a dipped piece, the glaze would take forever to dry, and would have cracking issues.  In many hours of research (and reading at times what seemed to be contradictory advice) , it sounded as though the addition of sodium silicate should thin down the glaze, which is what I thought I wanted to do. I even watched John Britt's video showing exactly what sodium silicate does to his glaze that was behaving like mine -- his thinned down nicely.  Mine, on the other hand, gelled up when I added sodium silicate!   How could that happen?  It seems counter-intuitive, and yet that's what happened.  I'm hoping to salvage this bucket of glaze -- is there any advice that will help me?

 

Thank you!

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I might not be the go to person with glazes, but I might try the damp sponge idea just to see.

But I'm old school so if this were my glaze, I'd add water and maybe sieve the glaze again.

We were taught that by dipping fingers in a regular glaze the hair on the knuckles should stick

out above the glaze... Raku glaze should be thicker keeping the hair down.  Nowadays, there are

health concerns about placing hands and arms in glazes.

Since you're own your own, you might want to add some water and dip a cup, mark it some how.  And

measure the gravity.(each time)

Add 8 oz, pint, or quart of water, and dip another cup and mark it, until it gets to the point where it appears to

be drying correctly and not appearing too thick.  Then fire the items, and refer to your notes upon

completion.  You'll find out from the experiments how much water and the gravity from the best rests will be.

Good luck.

Alabama

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Sodium silicate should have thinned down the glaze really, sounds like there is an ingredient in the glaze that is causing mischief. Is it a commercial glaze you have used before?

 

I remember reading stuff about glaze cracking/gelling and why but I can't remember it any more. I will see if I can find it again.

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Too much defloc ie sodium silicate will turn your glaze into custard.   This is from memory.

 Try adding some epsom salts to counteract this.

What's the recipe.

SPecific gravity ok for that glaze?

Used it before and it was ok?

What temp are you bisquing to?

Glaze recipe?

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Babs you're on target with sodium silicate turning the glaze to custard....it did! And everything I read indicated it would do just the opposite. I'm afraid I don't have the ingredients. It's Standard ceramic seamist commercial dry glaze. I understand not knowing the recipe limits me in understanding what to do to fix this bucket! I do have some Epsom salts already dissolved in water so I might as well try that (even though I've read that thickens glaze). I'll take the other advice to re-sieve. It's just so odd to have the specific gravity in the light side and have custard consistency. Aaarrggghh.

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Drop by drop with Epsom. Ditto when using sodium Silicate. It's to do with acid and base state of the liquid. thus electrical charge. Not a fixed state.

have a series of tiles which you dip as you add the epsom salts till you get what you want.

is this the first time you have used this glaze?

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Yes, first time I bought this glaze. It was too thick when mixed initially (following manufacturer's instruction), so added a little water. It went on the pieces beautifully but fired too thin. So I allowed the glaze to sit, then took off some water that separated on top. I have a feeling that's where I went wrong. There was probably some material in the water that I scooped off that threw the chemical or mineral balance out of whack.

 

I will add Epsom salts in tiny increments. Here's hoping...it's a beautiful glaze when it works.

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Yes, first time I bought this glaze. It was too thick when mixed initially (following manufacturer's instruction), so added a little water. It went on the pieces beautifully but fired too thin. So I allowed the glaze to sit, then took off some water that separated on top. I have a feeling that's where I went wrong. There was probably some material in the water that I scooped off that threw the chemical or mineral balance out of whack.

 

I will add Epsom salts in tiny increments. Here's hoping...it's a beautiful glaze when it works.

The goodness was not in the water you took off the top.But if it needed to be thicker than just remove small amounts at a time to test.Another way would be apply more glaze to get the same results.

When the glaze went on beautifully and then later has water on top just mix it up again-if you take this water off you will have to replace it with the same amount of water

Next time around just mix that water back into the glaze once you have the right thickness.

Adding sodium silicate should be done in small amounts.

Mark

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Mark, not knowing the glaze recipe there could be some soluble ingredient in there.

Too thick following the instructions... did you fire it?

Longer dip time may have worked ..

SOunds like it's the test test test test time! :)  :)

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Doesn't epsom salts help with suspension? How would it help make it less custard? Maybe it would.

 

To me it seems like the sodium silicate has some how helped flocculate the glaze instead of deflocculating. 

 

http://digitalfire.com/4sight/troubleshooting/ceramic_troubleshooting_glaze_slurry_is_difficult_to_use.html

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Somewhere, some time back, someone posted a link that explained what happens drop by drop when you add sodium silicate.  It starts by making it more fluid, then if you add too much it gels.  The test took you through the process where you left it overnight and then re-whisked next day to see what happened.  I think the link might have been "Alfred" or from the guy who had a major paddy about gerstley borate - whose name escapes me.  I'll have a hunt and see what I can find.

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Hurray, sort of found what I was looking for, but it was relating to slip not glaze.

 

Anyway, this is the topic it was mentioned in: http://community.ceramicartsdaily.org/topic/7327-store-bought-clay-slip-is-way-too-thick/ and this is a direct link:  http://digitalfire.com/4sight/education/understanding_the_deflocculation_process_in_slip_casting_213.html  

 

 

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Somewhere, some time back, someone posted a link that explained what happens drop by drop when you add sodium silicate.

 

You might mean this one from: http://community.ceramicartsdaily.org/topic/6627-red-casting-slip/?view=findpost&p=63301&hl=peterh

FYI I pass on an Alfred guide on making casting slip in case it is of any help to you in

judging the amount of deflocculant to use. You will have to judge its utility yourself, I

certainly haven't tried it. [Now I just tweak a UK porcelain casting slip pre-mix.]

 

http://claystore.alf... Procedures.pdf

... which seems to be an extract from a much larger document

http://www.claystore...ip casting).pdf

 

 

Also FIGURE 7.1.1-C part way down http://www.fastonline.org/CD3WD_40/CD3WD/APPRTECH/G16FOE/EN/B398_9.HTM

shows the viscosity sharply increasing on the addition of too much deflocculant (casting slip example again).

 

Regards, Peter

 

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Somewhere, some time back, someone posted a link that explained what happens drop by drop when you add sodium silicate.

 

You might mean this one from: http://community.ceramicartsdaily.org/topic/6627-red-casting-slip/?view=findpost&p=63301&hl=peterh

FYI I pass on an Alfred guide on making casting slip in case it is of any help to you in

judging the amount of deflocculant to use. You will have to judge its utility yourself, I

certainly haven't tried it. [Now I just tweak a UK porcelain casting slip pre-mix.]

 

http://claystore.alf... Procedures.pdf

Regards, Peter

 

 

Thanks Peter, that's the one I was thinking of.  http://claystore.alf... Procedures.pdf  Note to self - save this a bookmark! duh

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