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Which Do You Prefer For Joining Process?


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Do you use deflocculated slip, regular slip or magic water for joining.   ?

 

I have not tried deflocculated slip, just watched John Britt's video on You Tube on this and am considering it for a stiff slab project upcoming.  Are different processes better in different situations?

 

Some of my students get slabs too wet when using vinegar water, looking for a better way for them.

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I use a heavy slip made from dried bit of clay softened in a small quantity of water, with wet toilet paper added at about 20%.  Then the whole batch goes in a food processor, producing a silky smooth, sour cream consistency.  If I really want to make sure a seam holds up, I'll make a coil from very soft clay and press it onto one of the slipped edges. , When I press the two sides together, most of the coil squeezes out, but it does a great job of sealing any uneven fits.  

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I have used slip, slip with vinegar, slip with paper and vinegar. All of these worked fine, but the last few years of teaching, I used and still use "magic water". I found while teaching that I had fewer cracks in bisqueware, and less problems with pieces not joining on than with slip. I think one of the things that happened with slip, the kids would not get the idea of working the seam together by moving the pieces until seated well.

 

Always taught scoring and slip or magic water. Found that without the scoring that student work had more cracking and missing pieces.

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I have always used just plain ol' slip.  I grab a handful out of the bucket, mix it enough to smooth out the big chunks and go.

 

I have started to use some "Super Slip" for drier mends.  Babs sent me a recipe, and it works very well.  I mainly keep it around for student projects that crack or break, when bone dry.

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What is "magic water" and what is the purpose or property of the vinegar-and what kind of vinegar, in what amount? I have always used straight up slip with no problem, but this is interesting. Thx.

Magic Water is a mixture of water, sodium silicate and soda ash.  The sodium silicate helps the clay "fuse" together.  I've never used it myself, but I'm told it works great.

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Just to add: I have no trouble with joins coming apart in firing but I've seen it happen several times to others in my class - before you actually make the join the slip must still have a wet shine - it's no use making a long join and taking so long to apply the slip that it's dried before joining - if it has, apply more slip, (subsequent coats will take longer to dry, giving you a little more time)  it must look wet before you join.

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If you start with heavy slip, what does Sodium silicate do for you other than make it more runny without the addition of more water?  Does that reduce the shrinkage of the slip its self in the join?  That would make sense to me,   less shrinkage=less cracking.

 

Will it work without the soda ash?  What does the soda ash add to the effect?

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I understood that by defloculating the clay, i.e. separating the particles, it allows the two pieces being joined to meld. I use magic water and an old toothbrush to scuff up my pieces as I apply the magic water. I don't get cracks on seams or handles falling off. I didn't before either, but a gallon of the magic water lasts forever, so I stick to using it. It is easier than keeping slips for various clay bodies handy.

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If you have problems with joins then magic water alone or slip made with magic water or magic water slip made with paper pulp is worth a try. 

 

You are adding sodium (from the sodium silicate plus the soda ash) which is a strong flux which helps fuse the joins together. Also, the silica in the sodium silicate adds a titch more glass former to the join. Sodium silicate is also really sticky stuff which helps the joint bond plus slip made with it dries really hard. It also acts as a defloc and is water soluble so is able to work into the surrounding clay a bit. So in theory the bond is stronger while drying right through to the finished join having more melt and fusing better when fired.

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If you have problems with joins then magic water alone or slip made with magic water or magic water slip made with paper pulp is worth a try. 

 

You are adding sodium (from the sodium silicate plus the soda ash) which is a strong flux which helps fuse the joins together. Also, the silica in the sodium silicate adds a titch more glass former to the join. Sodium silicate is also really sticky stuff which helps the joint bond plus slip made with it dries really hard. It also acts as a defloc and is water soluble so is able to work into the surrounding clay a bit. So in theory the bond is stronger while drying right through to the finished join having more melt and fusing better when fired.

Do you make your own magic water or buy it? If you make your own what recipe do you use?

 

Since each clay body has a different % shrinkage, do you make up paper clay slip for each clay body?.....how manyclay bodies does everyone use in their studios? I would undoubtedly get my paper clay slips mixed up if I had many clay bodies.

 

Jed

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If you have problems with joins then magic water alone or slip made with magic water or magic water slip made with paper pulp is worth a try. 

 

You are adding sodium (from the sodium silicate plus the soda ash) which is a strong flux which helps fuse the joins together. Also, the silica in the sodium silicate adds a titch more glass former to the join. Sodium silicate is also really sticky stuff which helps the joint bond plus slip made with it dries really hard. It also acts as a defloc and is water soluble so is able to work into the surrounding clay a bit. So in theory the bond is stronger while drying right through to the finished join having more melt and fusing better when fired.

Do you make your own magic water or buy it? If you make your own what recipe do you use?

 

Since each clay body has a different % shrinkage, do you make up paper clay slip for each clay body?.....how manyclay bodies does everyone use in their studios? I would undoubtedly get my paper clay slips mixed up if I had many clay bodies.

 

Jed

 

 

I use the original Lana Wilson recipe for magic water that Foxden posted and use that for mixing the slip. I prefer using just the slip, I rarely use the paperclay version.(approx 1/5paper to 4/5 dry scraps by volume)

 

I just use tap water, not distilled like "Oldlady", I feel rude every time I write that, uses but then we have good water where we live so maybe that makes a difference?

 

Yup, use the same body for the slip as the pot is made from.

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For joining, I use slip made from the same clay body. I will mix that slip with either tap water or magic water, sometimes both. I have noticed that sometimes the magic water alone or magic water slip will make clay soft -- I do a lot of hard slab (as opposed to soft slab) work. For a lot of soft slab work, all you might need is water -- the clay is already moist enough to make a good bond.

 

Min -- just spent some time with Oldlady at the Bluemont Fair this weekend; her booth was across from mine. No need to feel rude using the moniker. And she does have an affinity for the glazes of the hippy potters of the '70s (1970's, that is).

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i just use clay slop from reclaim barrel mixed to yogurt consistency with water.  if the piece is more dry, i'll sometimes add vinegar to the mix since it's quick and simple.  have tried the magic water/paper slip once or twice, it was decent but when it's not immediately in my grasp it doesn't get utilized.

 

on larger structural joints for something like a 1" thick wall of a large sculpture - i like to slip/score with a plastic fork (just enough yield to not score too deep) and then take a sharpened chopstick and "stitch" the two sides together, followed by a small coil  smoothed over by fingertips and then rib the whole thing --- never had any issues with one of these seams coming apart, just make sure you don't trap much air when using this method.

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Hey,

 

While I usually work primarily with handles and knobs my method would cross over to general attachments.

When the vessels become leather hard, I take a count of them and make about two more handles than I

need, then set the handles aside to dry.  I usually do not lay them on their sides since it messes up the wet side

laying against the bat.  Then, I trim the vessels and if the handles are stiff enough I cut them to length

making the cuts concave to better fit the sides of the cups.  Once their cut, I place a dab of slip on each

cut then score the slip into the clay.  After that, I gently place the handle against the vessel leaving a touch

of slip on the vessel making sure the handle is lower than the lip or rim of the cup.  Then, more slip is applied to the

cup and scored into the clay.  Both scorings are horizonal so when they're attached they fit together better.

Once the handle is attached, I take a needle tool and push the clay from the handle into the vessel 360 degrees

around the attachments.  Before wrapping the vessel in a plastic bag and set it on a shelf,

 I smooth all the marks left by the needle tool.  I remove the bag 12 to 24 hours later, and allow to dry.

Even I know this is alittle OCD, but it works for me.  My theory behind this is that the handle is mostly going to

fail while in use and even if cracks appear around the attachments, the handles hold up.

BTW, I generally throw on square bats but trim on 12 inch round bats.  (seems to save finger nails,

when trimming on the smaller square bats.)

Hope this helps,

Alabama

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