iandol on mon 10 dec 01
Making a comparison between joints made with deflocculated slip, magic =
water or vinegar without roughing up the surface of either part and =
joints where splash pan slurry and deep scoring is used to roughly join =
part together is like comparing cheese with chalk.
In the former case we rely on the force of electrons between clay and =
water to hold the parts together. It is a precision process. In the =
latter we create a mechanical key so that one part is deformed and =
forced into the cavities made in the other part with a fork, needle =
tool or other sharp object. This is similar in action to a dovetail =
joint. I would reserve it for pieces which are thick, liable to high =
stress and where there is further modelling to be done.
Both techniques work. Both can be tested to destruction and their =
relative strengths compared. The advantage of deflocculated slip is it's =
low water volume to high clay volume ratio which ensures that shrinkage =
is minimised. Being a lower ration than that of clay on either side of =
the bonded area, there is reduced susceptibly to shrinkage fissures. =
Each method has a variety of differing uses.
Best regards,
Ivor Lewis. Redhill, South Australia
Judith I. Marvin on mon 10 dec 01
All right Ivor--I'll bite--what is "magic water"?
>From: iandol
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re....air bubbles?
>Date: Mon, 10 Dec 2001 16:52:15 +1030
>
>Making a comparison between joints made with deflocculated slip, magic
>water or vinegar without roughing up the surface of either part and joints
>where splash pan slurry and deep scoring is used to roughly join part
>together is like comparing cheese with chalk.
>
>In the former case we rely on the force of electrons between clay and water
>to hold the parts together. It is a precision process. In the latter we
>create a mechanical key so that one part is deformed and forced into the
>cavities made in the other part with a fork, needle tool or other sharp
>object. This is similar in action to a dovetail joint. I would reserve it
>for pieces which are thick, liable to high stress and where there is
>further modelling to be done.
>
>Both techniques work. Both can be tested to destruction and their relative
>strengths compared. The advantage of deflocculated slip is it's low water
>volume to high clay volume ratio which ensures that shrinkage is minimised.
>Being a lower ration than that of clay on either side of the bonded area,
>there is reduced susceptibly to shrinkage fissures. Each method has a
>variety of differing uses.
>
>Best regards,
>
>Ivor Lewis. Redhill, South Australia
>
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