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deflocculated to flocculated clay mixing

updated sun 16 jan 00

 

Kenneth D. Westfall on fri 14 jan 00

After several hours of IRC chatting about blunging and air drying clay. I
was wondering about the pit falls of blunging deflocculated clay, aging it
and then pouring into a soldner mixer and flocculating it back to a solid
clay? Would the finish clay lose its plasticity gain by blunging or would
it turn thixotropic? What would be the best flocculating and
deflocculating agent for this propose keeping in mind cheaper is better?
Kenneth D. Westfall
Pine Hill Pottery
R.D. #2 Box 6AA
Harrisville, WV 26362
pinehill@ruralnet.org
http://www.ruralnet.org/pinehillpottery

Michael Banks on sat 15 jan 00

You don't mention the density of the deflocced slip you wish to blunge or
the mesh size of the clay. These are critical factors in answering the
question. Defloccing natural clays with significant sand content can lead
to dropout and sedimentation fairly rapidly. Other data required are; the
composition type of clay and the required end-use, which determines choices
of deflocculants/flocculants.

But apart from these considerations, I see no problem with re-flocculating
the slip, but you will not end up with solid clay. I presume you are trying
to avoid having to de-water, or filter pressing the slip. You cannot avoid
de-watering in my experience. Flocculating say, a 1.6 gm/ml deflocculated
slip, results in a thicker slip, not solid clay. Casting slips become solid
clay in plaster moulds largely due to the filter pressing action of the
porous mould (which removes water by capillary action) as well as some
surface flocculation effects of the Ca ions in the plaster. To obtain a
solid clay you would have to obtain a blungable slip density of about 1.9
gm/ml or more, which I don't think is achievable.

Sorry mate, I think you need a filter press, or another de-watering method.

The cheapest defloc agent per weight effect is probably caustic soda (NaOH),
the cheapest and most powerful flocculants are industrial acids such as
hydrochloric (HCl). Both materials require care with storage and handling.

Michael Banks,
Nelson,
New Zealand


Kenneth D. Westfall wrote:
> ----------------------------Original message----------------------------
> After several hours of IRC chatting about blunging and air drying clay. I
> was wondering about the pit falls of blunging deflocculated clay, aging it
> and then pouring into a soldner mixer and flocculating it back to a solid
> clay? Would the finish clay lose its plasticity gain by blunging or would
> it turn thixotropic? What would be the best flocculating and
> deflocculating agent for this propose keeping in mind cheaper is better?
> Kenneth D. Westfall
> Pine Hill Pottery
> R.D. #2 Box 6AA
> Harrisville, WV 26362
> pinehill@ruralnet.org
> http://www.ruralnet.org/pinehillpottery
>