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Darvan 7 experience?


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#1 Dirtymudster

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Posted 27 February 2013 - 02:33 PM

Hi Folks, I'm going to be combining a dry clay mix with water and mason stains to color it before working with it. Then after I get it blended (likely in small batches in a blender) I plan to dry it somewhat on plaster until workable. I've gotten advice to use some Darvan 7, a deflocculant, to help with this. Does anyone have experience using this or with this process? Ideas / thoughts appreciated! Thanks.

#2 neilestrick

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Posted 27 February 2013 - 03:09 PM

The easiest non technical way to make a deflocculated slip is to mix the dry ingredients with a bunch of water and let it sit until it settles out. Then pour off all the excess water and stir in Darvan, just a drop or two at a time, until you get the viscosity you want. You'll need more stain in a slip than in a glaze, often up to 15% or more, depending on the color and how intense you want it.
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#3 Dirtymudster

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Posted 27 February 2013 - 03:30 PM

The easiest non technical way to make a deflocculated slip is to mix the dry ingredients with a bunch of water and let it sit until it settles out. Then pour off all the excess water and stir in Darvan, just a drop or two at a time, until you get the viscosity you want. You'll need more stain in a slip than in a glaze, often up to 15% or more, depending on the color and how intense you want it.


Thank you, Neil! Sounds good, though perhaps I should have clarified that my ultimate goal is colored clay for handbuilding, not slip casting...

#4 neilestrick

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Posted 27 February 2013 - 04:44 PM

You only need to deflocculate if you are making slip. I've never heard of deflocculating a clay body.
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#5 Marcia Selsor

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Posted 28 February 2013 - 09:47 AM

I use darvon in my colored slips. It helps keep the stains from settling.
I use my porcelain clay body, 10% Glomax and 10% stain ..which can increase or decrease depending on my need for shades.
I mix them in a blender. For clay bodies, check the reference codes.
Like Neil, I never heard of needing Darvon for a clay body.

I also use the darvon for making Terra Sig following Charlie Riggs method.


Marcia

#6 Dirtymudster

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Posted 28 February 2013 - 10:35 AM

I use darvon in my colored slips. It helps keep the stains from settling.
I use my porcelain clay body, 10% Glomax and 10% stain ..which can increase or decrease depending on my need for shades.
I mix them in a blender. For clay bodies, check the reference codes.
Like Neil, I never heard of needing Darvon for a clay body.

I also use the darvon for making Terra Sig following Charlie Riggs method.


Marcia


Marcia, thank you. That sounds similar to what I think I'm going to do. Perhaps a possible point of misunderstanding is that I plan on mixing the dry form of what wet would be a regular porcelain clay body. I wanted it in dry form just to increase the ease of mixing with stains by making it wetter/thinner than one normally would for a hand building clay. Then I'd like to dry it a bit on plaster until I can work it. Because I am new to this, I guess I don't know if there is a chemical difference between actual slip and just very thinned down clay? Maybe that's why I was told to use the Darvan 7, since I want to make it so watery at first...

#7 Marcia Selsor

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Posted 28 February 2013 - 11:05 AM

Yes, I thought you were drying it out to a clay body consistency.
I soak my trimmings and put them in a blender. Then I use small containers to pour out equal amounts.
I estimate the quantity from experience with glaze testing. So I pour out what I estimate to be 50 grams
of the mix. Then add the stain accordingly. I mix the slip as I need it.

Marcia

#8 Chris Campbell

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Posted 28 February 2013 - 11:35 AM

When a clay company mixed up some colored clay for me, I believe they added Bentonite ... which I think reacts somewhat like Darvan but I never asked why. I never noticed any short term difference in the clay but perhaps long term it might keep the clay plastic??
I've noticed that some of my own old colored clay gets very short so could this be what they were trying to prevent?

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#9 bciskepottery

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Posted 28 February 2013 - 05:40 PM

When a clay company mixed up some colored clay for me, I believe they added Bentonite ... which I think reacts somewhat like Darvan but I never asked why. I never noticed any short term difference in the clay but perhaps long term it might keep the clay plastic??
I've noticed that some of my own old colored clay gets very short so could this be what they were trying to prevent?



The bentonite might be added to help keep shrinkage compatible with the clay body and to offset any change due to the addition of the stains to the mix.

#10 perkolator

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Posted 28 February 2013 - 07:43 PM

bentonite is also usually added to clay body as a plasticizer. i would just mix up your clay into a THICK slip as planned - like pudding/yogurt consistency - then dry it out and wedge it up. it's either this or simply wedge stain into your clay, which is going to take a lot of elbow grease!




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