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Darvan #811 Soda Silica N Brand


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#1 Mug

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Posted 08 June 2014 - 03:04 PM

I made a trip to Standard for some supplies. I had to pick up some Darvan and Sodium silicate.

The lady in the store ask me why I was purchasing both, and she said they were exactly the same, just a different brand.

What are your thoughts?

I was thinking it was a little harder to over dose slip with Darvan. My recipe uses both.



#2 Mark C.

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Posted 08 June 2014 - 03:07 PM

Darvan  7 is the better product these days

You will not need sodium sil as well.

Mark


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#3 Babs

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Posted 08 June 2014 - 06:48 PM

Sodium Silicate + soda ash

 

Darvan on its own

Same effect different products.



#4 Mark C.

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Posted 08 June 2014 - 07:39 PM

The soda ash for me when I had a slip business was harder on the molds I felt than Darvan.

It was just a feeling.

Mark


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#5 JBaymore

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Posted 08 June 2014 - 08:30 PM

Darvan #7 is also my defloculant of chioice.

 

Not for putting on the clay for stretching... that is sodium silicate.

 

best,

 

..................john


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#6 ashraf elhamy

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Posted 09 June 2014 - 04:04 AM

Is any know what's the chemical formula of Darvan ????

#7 ashraf elhamy

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Posted 09 June 2014 - 06:13 AM

Dears
Is any one know a supplier for Darvan #7

#8 Tristan TDH

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Posted 09 June 2014 - 08:27 AM

2 products that do similar things to clay/slip/glaze, but are chemically completely different. Sodium silicate is just that, Darvan 7 is a long chain polyacrylic acid. Whereas Darvan 811 is a short chain polymer, with a low molecular weight, less appropriate for glaze, more so for clay and slip. A polymer that you would probably not be able to recreate without an advanced chemistry degree and a lab.
My experience with them is that Darvan created a more stable slurry and is much less caustic to both you and mold hydrocal/plaster. However, as John says above, if you are applying it to stretch clay and get a cracked effect, Sodium Silicate is the one to use. Both are inexpensive and easy to purchase from any well stocked pottery supplier. If you are in Philadelphia, where Standard is, you can get Darvan at the Ceramic Shop which I believe is on on Amber Street. Or order online from the Ceramic Shop, Axner, Clay King, Bailey, etc.

#9 Mark C.

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Posted 09 June 2014 - 09:59 AM

Dears
Is any one know a supplier for Darvan #7

Axner clay or Laguna Clay or any ceranic supplier

Mark


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#10 Mug

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Posted 09 June 2014 - 01:50 PM

I would like to keep my molds in good shape as long as possible.

No Sodium carbonate when using Darvan, Darvan 7 sounds like the way to go for healthy molds.

 

Long chain, short chain...could you dumb that down

Why is the seven better than the 811?

 

Do you guys use Barium Carbonate in your slip?



#11 Tristan TDH

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Posted 09 June 2014 - 07:11 PM

Long chain and short chain refers to the molecule length of the polymer. It reflects the molecular weight. I think the difference between the two is that Darvan 7 is appropriate for glaze and clay, whereas Darvan 811 is more appropriate for use with clay and slip. I only use Darvan 7, and really like the slip that I make when using it.
I learned the difference between the two when I was researching which one to use. One is not superior to the other, though I would say that for deflocculation they are both superior to Sodium silicate and soda ash, it just depends what you're using it for.

#12 Babs

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Posted 10 June 2014 - 12:22 AM

Not using much, I believe Darvan has a shorter shelf life?



#13 ashraf elhamy

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Posted 10 June 2014 - 08:10 AM

Thanks Mark C.




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